A Novel DNase Assay Reveals Low DNase Activity in Severe Asthma

Secreted deoxyribonucleases (DNases), such as DNase-1 and DNase-IL3, degrade extracellular DNA, and endogenous DNases have roles in resolving airway inflammation and guarding against autoimmune responses to nucleotides. Subsets of patients with asthma have high airway DNA levels, but information about DNase activity in health and in asthma is lacking. To characterize DNase activity in health and in asthma, we developed a novel kinetic assay using a Taqman probe sequence that is quickly cleaved by DNase-I to produce a large product signal. We used this kinetic assay to measure DNase activity in sputum from participants in the Severe Asthma Research Program (SARP)-3 (n=439) and from healthy controls (n=89). We found that DNase activity was lower than normal in asthma (78.7 RFU/min vs 120.4 RFU/min, p<0.0001). Compared to asthma patients with sputum DNase activity levels in the upper tertile activity levels, those in the lower tertile of sputum DNase activity were characterized clinically by more severe disease and pathologically by airway eosinophilia and airway mucus plugging. Carbamylation of DNase-I, a post translational modification that can be mediated by eosinophil peroxidase, inactivated DNase-I. In summary, a Taqman probe-based DNase activity assay uncovers low DNase activity in the asthma airway which is associated with more severe disease and airway mucus plugging and may be caused, at least in part, by eosinophil-mediated carbamylation.

Protein-Protein interactive networks identified in bronchoalveolar lavage of severe compared to nonsevere asthma

INTRODUCTION

Previous bronchoalveolar lavage fluid (BALF) proteomic analysis has evaluated limited numbers of subjects for only a few proteins of interest, which may differ between asthma and normal controls. Our objective was to examine a more comprehensive inflammatory biomarker panel in quantitative proteomic analysis for a large asthma cohort to identify molecular phenotypes distinguishing severe from nonsevere asthma.

METHODS

Bronchoalveolar lavage fluid from 48 severe and 77 nonsevere adult asthma subjects were assessed for 75 inflammatory proteins, normalized to BALF total protein concentration. Validation of BALF differences was sought through equivalent protein analysis of autologous sputum. Subjects' data, stratified by asthma severity, were analysed by standard statistical tests, principal component analysis and 5 machine learning algorithms.

RESULTS

The severe group had lower lung function and greater health care utilization. Significantly increased BALF proteins for severe asthma compared to nonsevere asthma were fibroblast growth factor 2 (FGF2), TGFα, IL1Ra, IL2, IL4, CCL8, CCL13 and CXCL7 and significantly decreased were platelet-derived growth factor a-a dimer (PDGFaa), vascular endothelial growth factor (VEGF), interleukin 5 (IL5), CCL17, CCL22, CXCL9 and CXCL10. Four protein differences were replicated in sputum. FGF2, PDGFaa and CXCL7 were independently identified by 5 machine learning algorithms as the most important variables for discriminating severe and nonsevere asthma. Increased and decreased proteins identified for the severe cluster showed significant protein-protein interactions for chemokine and cytokine signalling, growth factor activity, and eosinophil and neutrophil chemotaxis differing between subjects with severe and nonsevere asthma.

CONCLUSION

These inflammatory protein results confirm altered airway remodelling and cytokine/chemokine activity recruiting leukocytes into the airways of severe compared to nonsevere asthma as important processes even in stable status.

Persistent mucus plugs in proximal airways are consequential for airflow limitation in asthma

BACKGROUNDInformation about the size, airway location, and longitudinal behavior of mucus plugs in asthma is needed to understand their role in mechanisms of airflow obstruction and to rationally design muco-active treatments.METHODSCT lung scans from 57 patients with asthma were analyzed to quantify mucus plug size and airway location, and paired CT scans obtained 3 years apart were analyzed to determine plug behavior over time. Radiologist annotations of mucus plugs were incorporated in an image-processing pipeline to generate size and location information that was related to measures of airflow.RESULTSThe length distribution of 778 annotated mucus plugs was multimodal, and a 12 mm length defined short ("stubby", ≤12 mm) and long ("stringy", >12 mm) plug phenotypes. High mucus plug burden was disproportionately attributable to stringy mucus plugs. Mucus plugs localized predominantly to airway generations 6-9, and 47% of plugs in baseline scans persisted in the same airway for 3 years and fluctuated in length and volume. Mucus plugs in larger proximal generations had greater effects on spirometry measures than plugs in smaller distal generations, and a model of airflow that estimates the increased airway resistance attributable to plugs predicted a greater effect for proximal generations and more numerous mucus plugs.CONCLUSIONPersistent mucus plugs in proximal airway generations occur in asthma and demonstrate a stochastic process of formation and resolution over time. Proximal airway mucus plugs are consequential for airflow and are in locations amenable to treatment by inhaled muco-active drugs or bronchoscopy.TRIAL REGISTRATIONClinicaltrials.gov; NCT01718197, NCT01606826, NCT01750411, NCT01761058, NCT01761630, NCT01716494, and NCT01760915.FUNDINGAstraZeneca, Boehringer-Ingelheim, Genentech, GlaxoSmithKline, Sanofi-Genzyme-Regeneron, and TEVA provided financial support for study activities at the Coordinating and Clinical Centers beyond the third year of patient follow-up. These companies had no role in study design or data analysis, and the only restriction on the funds was that they be used to support the SARP initiative.

A Novel Air Trapping Segment Score Identifies Opposing Effects of Obesity and Eosinophilia on Air Trapping in Asthma

BACKGROUND

Density thresholds in computed tomography (CT) lung scans quantify air trapping (AT) at the whole lung level but are not informative for AT in specific bronchopulmonary segments.

OBJECTIVES

To apply a segment-based measure of AT in asthma to investigate the clinical determinants of AT in asthma.

METHODS

In each of 19 bronchopulmonary segments in CT lung scans from 199 asthma patients, AT was categorized as present if lung attenuation was < -856 Hounsfield units at expiration in ≥ 15% of lung area. The resulting AT segment score (0-19) was related to patient outcomes.

RESULTS

AT varied at the lung segment level and tended to persist at the patient and lung segment level over 3 years. Patients with widespread AT (>10 segments) had more severe asthma (p<0.05). The mean (± SD) AT segment score in patients with a BMI > 30 was lower than in patients with a BMI < 30 (3.5 ± 4.6 vs. 5.5 ± 6.3, p=0.008), and the frequency of AT in lower lobe segments in obese patients was less than in upper and middle lobe segments (35 vs. 46%, p=0.001). The AT segment score in patients with sputum eosinophil % > 2 was higher than in patients without sputum eosinophilia (7.0 ± 6.1 vs. 3.3 ± 4.9, p<0.0001). Lung segments with AT more frequently had airway mucus plugging than lung segments without AT (48 vs. 18%, p≤0.0001).

CONCLUSIONS

In patients with asthma, air trapping is more severe in those with airway eosinophilia and mucus plugging whereas those who are obese have less severe trapping because their lower lobe segments are spared.

Mitochondrial DNA Copy Number Variation in Asthma Risk, Severity, and Exacerbations

Rationale

Although airway oxidative stress and inflammation are central to asthma pathogenesis, there is limited knowledge of the relationship of asthma risk, severity, or exacerbations to mitochondrial dysfunction, which is pivotal to oxidant generation and inflammation.

Objectives

We investigated whether mitochondrial DNA copy number (mtDNA-CN) as a measure of mitochondrial function is associated with asthma diagnosis, severity, oxidative stress, and exacerbations.

Methods

We measured mtDNA-CN in blood in two cohorts. In the UK Biobank (UKB), we compared mtDNA-CN in mild and moderate-severe asthmatics to non-asthmatics. In the Severe Asthma Research Program (SARP), we evaluated mtDNA-CN in relation to asthma severity, biomarkers of oxidative stress and inflammation, and exacerbations.

Measures and Main Results

In UK Biobank, asthmatics (n = 29,768) have lower mtDNA-CN compared to non-asthmatics (n = 239,158) (beta, -0.026 [95% CI, -0.038 to -0.014], P = 2.46×10-5). While lower mtDNA-CN is associated with asthma, mtDNA-CN did not differ by asthma severity in either UKB or SARP. Biomarkers of inflammation show that asthmatics have higher white blood cells (WBC), neutrophils, eosinophils, fraction exhaled nitric oxide (FENO), and lower superoxide dismutase (SOD) than non-asthmatics, confirming greater oxidative stress in asthma. In one year follow-up in SARP, higher mtDNA-CN is associated with reduced risk of three or more exacerbations in the subsequent year (OR 0.352 [95% CI, 0.164 to 0.753], P = 0.007).

Conclusions

Asthma is characterized by mitochondrial dysfunction. Higher mtDNA-CN identifies an exacerbation-resistant asthma phenotype, suggesting mitochondrial function is important in exacerbation risk.

Investigations of a combination of atopic status and age of asthma onset identify asthma subphenotypes

OBJECTIVE

Subphenotypes of asthma may be determined by age onset and atopic status. We sought to characterize early or late onset atopic asthma with fungal or non-fungal sensitization (AAFS or AANFS) and non-atopic asthma (NAA) in children and adults in the Severe Asthma Research Program (SARP). SARP is an ongoing project involving well-phenotyped patients with mild to severe asthma.

METHODS

Phenotypic comparisons were performed using Kruskal-Wallis or chi-square test. Genetic association analyses were performed using logistic or linear regression.

RESULTS

Airway hyper-responsiveness, total serum IgE levels, and T2 biomarkers showed an increasing trend from NAA to AANFS and then to AAFS. Children and adults with early onset asthma had greater % of AAFS than adults with late onset asthma (46% and 40% vs. 32%; P < 0.00001). In children, AAFS and AANFS had lower % predicted FEV1 (86% and 91% vs. 97%) and greater % of patients with severe asthma than NAA (61% and 59% vs. 43%). In adults with early or late onset asthma, NAA had greater % of patients with severe asthma than AANFS and AAFS (61% vs. 40% and 37% or 56% vs. 44% and 49%). The G allele of rs2872507 in GSDMB had higher frequency in AAFS than AANFS and NAA (0.63 vs. 0.55 and 0.55), and associated with earlier age onset and asthma severity.

CONCLUSIONS

Early or late onset AAFS, AANFS, and NAA have shared and distinct phenotypic characteristics in children and adults. AAFS is a complex disorder involving genetic susceptibility and environmental factors.

Genetic analyses of chr11p15.5 region identify MUC5AC-MUC5B associated with asthma-related phenotypes

OBJECTIVE

Genome-wide association studies (GWASs) have identified single nucleotide polymorphisms (SNPs) in chr11p15.5 region associated with asthma and idiopathic interstitial pneumonias (IIPs). We sought to identify functional genes for asthma by combining SNPs and mRNA expression in bronchial epithelial cells (BEC) in the Severe Asthma Research Program (SARP).

METHODS

Correlation analyses of mRNA expression of six candidate genes (AP2A2, MUC6, MUC2, MUC5AC, MUC5B, and TOLLIP) and asthma phenotypes were performed in the longitudinal cohort (n = 156) with RNAseq in BEC, and replicated in the cross-sectional cohort (n = 155). eQTL (n = 114) and genetic association analysis of asthma severity (426 severe vs. 531 non-severe asthma) were performed, and compared with previously published GWASs of IIPs and asthma.

RESULTS

Higher expression of AP2A2 and MUC5AC and lower expression of MUC5B in BEC were correlated with asthma, asthma exacerbations, and T2 biomarkers (P < 0.01). SNPs associated with asthma and IIPs in previous GWASs were eQTL SNPs for MUC5AC, MUC5B, or TOLLIP, however, they were not in strong linkage disequilibrium. The risk alleles for asthma or protective alleles for IIPs were associated with higher expression of MUC5AC and lower expression of MUC5B. rs11603634, rs12788104, and rs28415845 associated with moderate-to-severe asthma or adult onset asthma in previous GWASs were not associated with asthma severity (P > 0.8).

CONCLUSIONS

SNPs associated with asthma in chr11p15.5 region are not associated with asthma severity neither with IIPs. Higher expression of MUC5AC and lower expression of MUC5B are risk for asthma but protective for IIPs.

CCL5 is a potential bridge between type 1 and type 2 inflammation in asthma

BACKGROUND

Type 1 (T1) inflammation (marked by IFN-γ expression) is now consistently identified in subsets of asthma cohorts, but how it contributes to disease remains unclear.

OBJECTIVE

We sought to understand the role of CCL5 in asthmatic T1 inflammation and how it interacts with both T1 and type 2 (T2) inflammation.

METHODS

CCL5, CXCL9, and CXCL10 messenger RNA expression from sputum bulk RNA sequencing, as well as clinical and inflammatory data were obtained from the Severe Asthma Research Program III (SARP III). CCL5 and IFNG expression from bronchoalveolar lavage cell bulk RNA sequencing was obtained from the Immune Mechanisms in Severe Asthma (IMSA) cohort and expression related to previously identified immune cell profiles. The role of CCL5 in tissue-resident memory T-cell (TRM) reactivation was evaluated in a T1high murine severe asthma model.

RESULTS

Sputum CCL5 expression strongly correlated with T1 chemokines (P < .001 for CXCL9 and CXCL10), consistent with a role in T1 inflammation. CCL5high participants had greater fractional exhaled nitric oxide (P = .009), blood eosinophils (P < .001), and sputum eosinophils (P = .001) in addition to sputum neutrophils (P = .001). Increased CCL5 bronchoalveolar lavage expression was unique to a previously described T1high/T2variable/lymphocytic patient group in the IMSA cohort, with IFNG trending with worsening lung obstruction only in this group (P = .083). In a murine model, high expression of the CCL5 receptor CCR5 was observed in TRMs and was consistent with a T1 signature. A role for CCL5 in TRM activation was supported by the ability of the CCR5 inhibitor maraviroc to blunt reactivation.

CONCLUSION

CCL5 appears to contribute to TRM-related T1 neutrophilic inflammation in asthma while paradoxically also correlating with T2 inflammation and with sputum eosinophilia.

A novel thiol-saccharide mucolytic for the treatment of muco-obstructive lung diseases

BACKGROUND

Mucin disulfide cross-links mediate pathologic mucus formation in muco-obstructive lung diseases. MUC-031, a novel thiol-modified carbohydrate compound, cleaves disulfides to cause mucolysis. The aim of this study was to determine the mucolytic and therapeutic effects of MUC-031 in sputum from patients with cystic fibrosis (CF) and mice with muco-obstructive lung disease (βENaC-Tg mice).

METHODS

We compared the mucolytic efficacy of MUC-031 and existing mucolytics (N-acetylcysteine (NAC) and recombinant human deoxyribonuclease I (rhDNase)) using rheology to measure the elastic modulus (G') of CF sputum, and we tested effects of MUC-031 on airway mucus plugging, inflammation and survival in βENaC-Tg mice to determine its mucolytic efficacy in vivo.

RESULTS

In CF sputum, compared to the effects of rhDNase and NAC, MUC-031 caused a larger decrease in sputum G', was faster in decreasing sputum G' by 50% and caused mucolysis of a larger proportion of sputum samples within 15 min of drug addition. Compared to vehicle control, three treatments with MUC-031 in 1 day in adult βENaC-Tg mice decreased airway mucus content (16.8±3.2 versus 7.5±1.2 nL·mm-2, p<0.01) and bronchoalveolar lavage cells (73 833±6930 versus 47 679±7736 cells·mL-1, p<0.05). Twice-daily treatment with MUC-031 for 2 weeks also caused decreases in these outcomes in adult and neonatal βENaC-Tg mice and reduced mortality from 37% in vehicle-treated βENaC-Tg neonates to 21% in those treated with MUC-031 (p<0.05).

CONCLUSION

MUC-031 is a potent and fast-acting mucolytic that decreases airway mucus plugging, lessens airway inflammation and improves survival in βENaC-Tg mice. These data provide rationale for human trials of MUC-031 in muco-obstructive lung diseases.

Low CC16 mRNA Expression Levels in Bronchial Epithelial Cells Are Associated with Asthma Severity

Rationale: CC16 is a protein mainly produced by nonciliated bronchial epithelial cells (BECs) that participates in host defense. Reduced CC16 protein concentrations in BAL and serum are associated with asthma susceptibility. Objectives: Few studies have investigated the relationship between CC16 and asthma progression, and none has focused on BECs. In this study, we sought to determine if CC16 mRNA expression levels in BECs are associated with asthma severity. Methods: Association analyses between CC16 mRNA expression levels in BECs (242 asthmatics and 69 control subjects) and asthma-related phenotypes in Severe Asthma Research Program were performed using a generalized linear model. Measurements and Main Results: Low CC16 mRNA expression levels in BECs were significantly associated with asthma susceptibility and asthma severity, high systemic corticosteroids use, high retrospective and prospective asthma exacerbations, and low pulmonary function. Low CC16 mRNA expression levels were significantly associated with high T2 inflammation biomarkers (fractional exhaled nitric oxide and sputum eosinophils). CC16 mRNA expression levels were negatively correlated with expression levels of Th2 genes (IL1RL1, POSTN, SERPINB2, CLCA1, NOS2, and MUC5AC) and positively correlated with expression levels of Th1 and inflammation genes (IL12A and MUC5B). A combination of two nontraditional T2 biomarkers (CC16 and IL-6) revealed four asthma endotypes with different characteristics of T2 inflammation, obesity, and asthma severity. Conclusions: Our findings indicate that low CC16 mRNA expression levels in BECs are associated with asthma susceptibility, severity, and exacerbations, partially through immunomodulation of T2 inflammation. CC16 is a potential nontraditional T2 biomarker for asthma development and progression.

Skeletal Muscle Adiposity and Lung Function Trajectory in the Severe Asthma Research Program

Rationale: Extrapulmonary manifestations of asthma, including fatty infiltration in tissues, may reflect systemic inflammation and influence lung function and disease severity. Objectives: To determine if skeletal muscle adiposity predicts lung function trajectory in asthma. Methods: Adult SARP III (Severe Asthma Research Program III) participants with baseline computed tomography imaging and longitudinal postbronchodilator FEV1% predicted (median follow-up 5 years [1,132 person-years]) were evaluated. The mean of left and right paraspinous muscle density (PSMD) at the 12th thoracic vertebral body was calculated (Hounsfield units [HU]). Lower PSMD reflects higher muscle adiposity. We derived PSMD reference ranges from healthy control subjects without asthma. A linear multivariable mixed-effects model was constructed to evaluate associations of baseline PSMD and lung function trajectory stratified by sex. Measurements and Main Results: Participants included 219 with asthma (67% women; mean [SD] body mass index, 32.3 [8.8] kg/m2) and 37 control subjects (51% women; mean [SD] body mass index, 26.3 [4.7] kg/m2). Participants with asthma had lower adjusted PSMD than control subjects (42.2 vs. 55.8 HU; P < 0.001). In adjusted models, PSMD predicted lung function trajectory in women with asthma (β = -0.47 Δ slope per 10-HU decrease; P = 0.03) but not men (β = 0.11 Δ slope per 10-HU decrease; P = 0.77). The highest PSMD tertile predicted a 2.9% improvement whereas the lowest tertile predicted a 1.8% decline in FEV1% predicted among women with asthma over 5 years. Conclusions: Participants with asthma have lower PSMD, reflecting greater muscle fat infiltration. Baseline PSMD predicted lung function decline among women with asthma but not men. These data support an important role of metabolic dysfunction in lung function decline.

The Impact of Insulin Resistance on Loss of Lung Function and Response to Treatment in Asthma

Rationale: The role of obesity-associated insulin resistance (IR) in airflow limitation in asthma is uncertain. Objectives: Using data in the Severe Asthma Research Program 3 (SARP-3), we evaluated relationships between homeostatic measure of IR (HOMA-IR), lung function (cross-sectional and longitudinal analyses), and treatment responses to bronchodilators and corticosteroids. Methods: HOMA-IR values were categorized as without (<3.0), moderate (3.0-5.0), or severe (>5.0). Lung function included FEV1 and FVC measured before and after treatment with inhaled albuterol and intramuscular triamcinolone acetonide and yearly for 5 years. Measurements and Main Results: Among 307 participants in SARP-3, 170 (55%) were obese and 140 (46%) had IR. Compared with patients without IR, those with IR had significantly lower values for FEV1 and FVC, and these lower values were not attributable to obesity effects. Compared with patients without IR, those with IR had lower FEV1 responses to β-adrenergic agonists and systemic corticosteroids. The annualized decline in FEV1 was significantly greater in patients with moderate IR (-41 ml/year) and severe IR (-32 ml/year,) than in patients without IR (-13 ml/year, P < 0.001 for both comparisons). Conclusions: IR is common in asthma and is associated with lower lung function, accelerated loss of lung function, and suboptimal lung function responses to bronchodilator and corticosteroid treatments. Clinical trials in patients with asthma and IR are needed to determine if improving IR might also improve lung function.

Urinary total conjugated 3-bromotyrosine, asthma severity, and exacerbation risk

Asthma is an inflammatory disease of the airways characterized by eosinophil recruitment, eosinophil peroxidase release, and protein oxidation through bromination, which following tissue remodeling results in excretion of 3-bromotyrosine. Predicting exacerbations and reducing their frequency is critical for the treatment of severe asthma. In this study, we aimed to investigate whether urinary total conjugated bromotyrosine can discriminate asthma severity and predict asthma exacerbations. We collected urine from participants with severe (n = 253) and nonsevere (n = 178) asthma, and the number of adjudicated exacerbations in 1-yr longitudinal follow-up was determined among subjects enrolled in the Severe Asthma Research Program, a large-scale National Institutes of Health (NIH)-funded consortium. Urine glucuronidated bromotyrosine and total conjugated forms were quantified by hydrolysis with either glucuronidase or methanesulfonic acid, respectively, followed by liquid chromatography-tandem mass spectrometry analyses of free 3-bromotyrosine. Blood and sputum eosinophils were also counted. The majority of 3-bromotyrosine in urine was found to exist in conjugated forms, with glucuronidated bromotyrosine representing approximately a third, and free bromotyrosine less than 1% of total conjugated bromotyrosine. Total conjugated bromotyrosine was poorly correlated with blood (r2 = 0.038) or sputum eosinophils (r2 = 0.0069). Compared with participants with nonsevere asthma, participants with severe asthma had significantly higher urinary total conjugated bromotyrosine levels. Urinary total conjugated bromotyrosine was independently associated with asthma severity, correlated with the number of asthma exacerbations, and served as a predictor of asthma exacerbation risk over 1-yr of follow-up.

DNA sequencing analysis of cystic fibrosis transmembrane conductance regulator gene identifies cystic fibrosis-associated variants in the Severe Asthma Research Program

BACKGROUND

Heterozygote carriers of potentially pathogenic variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene have increased asthma risk. However, the frequency and impact of CFTR variation among individuals with asthma is unknown.

OBJECTIVE

To determine whether potentially pathogenic CFTR variants associate with disease severity and whether individuals with two potentially pathogenic variants exist in a severe asthma-enriched cohort.

METHODS

We analyzed sequencing data spanning a 190.5Kb region of CFTR in participants from the Severe Asthma Research Program (SARP1-3). Potentially pathogenic, rare CFTR variants (frequency < 0.05) were classified as CF-causing or of varying clinical consequences (VVCC) (CFTR2. org). Regression-based models tested for association between CFTR genotypes (0-2 potentially pathogenic variants) and severity outcomes.

RESULTS

Of 1401 participants, 9.5% (134) had one potentially pathogenic variant, occurring more frequently in non-Hispanic white (NHW, 10.1% [84 of 831]) compared to African American individuals (AA, 5.2% [22 of 426]). We found ≥2 potentially pathogenic CFTR variants in 1.4% (19); 0.5% (4) of NHW and 2.8% (12) of AA. Potentially pathogenic CFTR variant genotypes (≥1 or ≥2 variants) were not cumulatively associated with lung function or exacerbations. In NHW, we found three F508del compound heterozygotes with F508del and a VVCC (two 5 T; TG12[c.1210-11 T > G] and one Arg1070Trp) and a homozygote for the VVCC, 5 T; TG12.

CONCLUSIONS

We found potentially pathogenic CFTR variants within a severe asthma-enriched cohort, including three compound heterozygote genotypes variably associated with CF in NHW individuals. These findings provide the rationale for CFTR sequencing and phenotyping of CF-related traits in individuals with severe asthma.

Exploring antiviral and anti-inflammatory effects of thiol drugs in COVID-19

The redox status of the cysteine-rich SARS-CoV-2 spike glycoprotein (SARS-2-S) is important for the binding of SARS-2-S to angiotensin-converting enzyme 2 (ACE2), suggesting that drugs with a functional thiol group (“thiol drugs”) may cleave cystines to disrupt SARS-CoV-2 cell entry. In addition, neutrophil-induced oxidative stress is a mechanism of COVID-19 lung injury, and the antioxidant and anti-inflammatory properties of thiol drugs, especially cysteamine, may limit this injury. To first explore the antiviral effects of thiol drugs in COVID-19, we used an ACE-2 binding assay and cell entry assays utilizing reporter pseudoviruses and authentic SARS-CoV-2 viruses. We found that multiple thiol drugs inhibit SARS-2-S binding to ACE2 and virus infection. The most potent drugs were effective in the low millimolar range, and IC₅₀ values followed the order of their cystine cleavage rates and lower thiol pK_a values. To determine if thiol drugs have antiviral effects in vivo and to explore any anti-inflammatory effects of thiol drugs in COVID-19, we tested the effects of cysteamine delivered intraperitoneally to hamsters infected with SARS-CoV-2. Cysteamine did not decrease lung viral infection, but it significantly decreased lung neutrophilic inflammation and alveolar hemorrhage. We speculate that the concentration of cysteamine achieved in the lungs with intraperitoneal delivery was insufficient for antiviral effects but sufficient for anti-inflammatory effects. We conclude that thiol drugs decrease SARS-CoV-2 lung inflammation and injury, and we provide rationale for future studies to test if direct (aerosol) delivery of thiol drugs to the airways might also result in antiviral effects.

Mucus Plugs Persist in Asthma, and Changes in Mucus Plugs Associate with Changes in Airflow over Time

Rationale: Cross-sectional analysis of mucus plugs in computed tomography (CT) lung scans in the Severe Asthma Research Program (SARP)-3 showed a high mucus plug phenotype. Objectives: To determine if mucus plugs are a persistent asthma phenotype and if changes in mucus plugs over time associate with changes in lung function. Methods: In a longitudinal analysis of baseline and Year 3 CT lung scans in SARP-3 participants, radiologists generated mucus plug scores to assess mucus plug persistence over time. Changes in mucus plug score were analyzed in relation to changes in lung function and CT air trapping measures. Measurements and Main Results: In 164 participants, the mean (range) mucus plug score was similar at baseline and Year 3 (3.4 [0-20] vs. 3.8 [0-20]). Participants and bronchopulmonary segments with a baseline plug were more likely to have plugs at Year 3 than those without baseline plugs (risk ratio, 2.8; 95% confidence interval [CI], 2.0-4.1; P < 0.001; and risk ratio, 5.0; 95% CI, 4.5-5.6; P < 0.001, respectively). The change in mucus plug score from baseline to Year 3 was significantly negatively correlated with change in FEV1% predicted (rp = -0.35; P < 0.001) and with changes in CT air trapping measures (all P values < 0.05). Conclusions: Mucus plugs identify a persistent asthma phenotype, and susceptibility to mucus plugs occurs at the subject and the bronchopulmonary segment level. The association between change in mucus plug score and change in airflow over time supports a causal role for mucus plugs in mechanisms of airflow obstruction in asthma.

Quantitative CT Characteristics of Cluster Phenotypes in the Severe Asthma Research Program Cohorts

Background Clustering key clinical characteristics of participants in the Severe Asthma Research Program (SARP), a large, multicenter prospective observational study of patients with asthma and healthy controls, has led to the identification of novel asthma phenotypes. Purpose To determine whether quantitative CT (qCT) could help distinguish between clinical asthma phenotypes. Materials and Methods A retrospective cross-sectional analysis was conducted with the use of qCT images (maximal bronchodilation at total lung capacity [TLC], or inspiration, and functional residual capacity [FRC], or expiration) from the cluster phenotypes of SARP participants (cluster 1: minimal disease; cluster 2: mild, reversible; cluster 3: obese asthma; cluster 4: severe, reversible; cluster 5: severe, irreversible) enrolled between September 2001 and December 2015. Airway morphometry was performed along standard paths (RB1, RB4, RB10, LB1, and LB10). Corresponding voxels from TLC and FRC images were mapped with use of deformable image registration to characterize disease probability maps (DPMs) of functional small airway disease (fSAD), voxel-level volume changes (Jacobian), and isotropy (anisotropic deformation index [ADI]). The association between cluster assignment and qCT measures was evaluated using linear mixed models. Results A total of 455 participants were evaluated with cluster assignments and CT (mean age ± SD, 42.1 years ± 14.7; 270 women). Airway morphometry had limited ability to help discern between clusters. DPM fSAD was highest in cluster 5 (cluster 1 in SARP III: 19.0% ± 20.6; cluster 2: 18.9% ± 13.3; cluster 3: 24.9% ± 13.1; cluster 4: 24.1% ± 8.4; cluster 5: 38.8% ± 14.4; P < .001). Lower whole-lung Jacobian and ADI values were associated with greater cluster severity. Compared to cluster 1, cluster 5 lung expansion was 31% smaller (Jacobian in SARP III cohort: 2.31 ± 0.6 vs 1.61 ± 0.3, respectively, P < .001) and 34% more isotropic (ADI in SARP III cohort: 0.40 ± 0.1 vs 0.61 ± 0.2, P < .001). Within-lung Jacobian and ADI SDs decreased as severity worsened (Jacobian SD in SARP III cohort: 0.90 ± 0.4 for cluster 1; 0.79 ± 0.3 for cluster 2; 0.62 ± 0.2 for cluster 3; 0.63 ± 0.2 for cluster 4; and 0.41 ± 0.2 for cluster 5; P < .001). Conclusion Quantitative CT assessments of the degree and intraindividual regional variability of lung expansion distinguished between well-established clinical phenotypes among participants with asthma from the Severe Asthma Research Program study. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Verschakelen in this issue.

Obesity alters pathology and treatment response in inflammatory disease

Decades of work have elucidated cytokine signalling and transcriptional pathways that control T cell differentiation and have led the way to targeted biologic therapies that are effective in a range of autoimmune, allergic and inflammatory diseases. Recent evidence indicates that obesity and metabolic disease can also influence the immune system1-7, although the mechanisms and effects on immunotherapy outcomes remain largely unknown. Here, using two models of atopic dermatitis, we show that lean and obese mice mount markedly different immune responses. Obesity converted the classical type 2 T helper (TH2)-predominant disease associated with atopic dermatitis to a more severe disease with prominent TH17 inflammation. We also observed divergent responses to biologic therapies targeting TH2 cytokines, which robustly protected lean mice but exacerbated disease in obese mice. Single-cell RNA sequencing coupled with genome-wide binding analyses revealed decreased activity of nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ) in TH2 cells from obese mice relative to lean mice. Conditional ablation of PPARγ in T cells revealed that PPARγ is required to focus the in vivo TH response towards a TH2-predominant state and prevent aberrant non-TH2 inflammation. Treatment of obese mice with a small-molecule PPARγ agonist limited development of TH17 pathology and unlocked therapeutic responsiveness to targeted anti-TH2 biologic therapies. These studies reveal the effects of obesity on immunological disease and suggest a precision medicine approach to target the immune dysregulation caused by obesity.

The Precision Interventions for Severe and/or Exacerbation-Prone (PrecISE) Asthma Network: An overview of Network organization, procedures, and interventions

Asthma is a heterogeneous disease, with multiple underlying inflammatory pathways and structural airway abnormalities that impact disease persistence and severity. Recent progress has been made in developing targeted asthma therapeutics, especially for subjects with eosinophilic asthma. However, there is an unmet need for new approaches to treat patients with severe and exacerbation-prone asthma, who contribute disproportionately to disease burden. Extensive deep phenotyping has revealed the heterogeneous nature of severe asthma and identified distinct disease subtypes. A current challenge in the field is to translate new and emerging knowledge about different pathobiologic mechanisms in asthma into patient-specific therapies, with the ultimate goal of modifying the natural history of disease. Here, we describe the Precision Interventions for Severe and/or Exacerbation-Prone Asthma (PrecISE) Network, a groundbreaking collaborative effort of asthma researchers and biostatisticians from around the United States. The PrecISE Network was designed to conduct phase II/proof-of-concept clinical trials of precision interventions in the population with severe asthma, and is supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health. Using an innovative adaptive platform trial design, the PrecISE Network will evaluate up to 6 interventions simultaneously in biomarker-defined subgroups of subjects. We review the development and organizational structure of the PrecISE Network, and choice of interventions being studied. We hope that the PrecISE Network will enhance our understanding of asthma subtypes and accelerate the development of therapeutics for severe asthma.

Mucus Plugs in Asthma at CT Associated with Regional Ventilation Defects at 3He MRI

Background Airway mucus plugs in asthma are associated with exacerbation frequency, increased eosinophilia, and reduced lung function. The relationship between mucus plugs and spatially overlapping ventilation abnormalities observed at hyperpolarized gas MRI has not been assessed quantitatively. Purpose To assess regional associations between CT mucus plugs scored by individual bronchopulmonary segment and corresponding measurements of segmental ventilation defect percentage (VDP) at hyperpolarized helium 3 (³He) MRI. Materials and Methods In this secondary analysis of a Health Insurance Portability and Accountability Act-compliant prospective observational cohort, participants in the Severe Asthma Research Program (SARP) III (NCT01760915) between December 2012 and August 2015 underwent hyperpolarized ³He MRI to determine segmental VDP. Segmental mucus plugs at CT were scored by two readers, with segments scored as plugged only if both readers agreed independently. A linear mixed-effects model controlling for interpatient variability was then used to assess differences in VDP in plugged versus plug-free segments. Results Forty-four participants with asthma were assessed (mean age ± standard deviation, 47 years ± 15; 29 women): 19 with mild-to-moderate asthma and 25 with severe asthma. Mucus plugs were observed in 49 total bronchopulmonary segments across eight of 44 patients. Segments containing mucus plugs had a median segmental VDP of 25.9% (25th-75th percentile, 7.3%-38.3%) versus 1.4% (25th-75th percentile, 0.1%-5.2%; P < .001) in plug-free segments. Similarly, the model estimated a segmental VDP of 18.9% (95% CI: 15.7, 22.2) for mucus-plugged segments versus 5.1% (95% CI: 3.3, 7.0) for plug-free segments (P < .001). Participants with one or more mucus plugs had a median whole-lung VDP of 11.1% (25th-75th percentile, 7.1%-18.9%) versus 3.1% (25th-75th percentile, 1.1%-4.4%) in those without plugs (P < .001). Conclusion Airway mucus plugging at CT was associated with reduced ventilation in the same bronchopulmonary segment at hyperpolarized helium 3 MRI, suggesting that mucus plugging may be an important cause of ventilation defects in asthma. © RSNA, 2021 Online supplemental material is available for this article.

Thiol drugs decrease SARS-CoV-2 lung injury in vivo and disrupt SARS-CoV-2 spike complex binding to ACE2 in vitro

Neutrophil-induced oxidative stress is a mechanism of lung injury in COVID-19, and drugs with a functional thiol group (“thiol drugs”), especially cysteamine, have anti-oxidant and anti-inflammatory properties that could limit this injury. Thiol drugs may also alter the redox status of the cysteine-rich SARS-CoV-2 spike glycoprotein (SARS-2-S) and thereby disrupt ACE2 binding. Using ACE2 binding assay, reporter virus pseudotyped with SARS-CoV-2 spikes (ancestral and variants) and authentic SARS-CoV-2 (Wuhan-1), we find that multiple thiol drugs inhibit SARS-2-S binding to ACE2 and virus entry into cells. Pseudoviruses carrying variant spikes were less efficiently inhibited as compared to pseudotypes bearing an ancestral spike, but the most potent drugs still inhibited the Delta variant in the low millimolar range. IC50 values followed the order of their cystine cleavage rates and lower thiol pKa values. In hamsters infected with SARS-CoV-2, intraperitoneal (IP) cysteamine decreased neutrophilic inflammation and alveolar hemorrhage in the lungs but did not decrease viral infection, most likely because IP delivery could not achieve millimolar concentrations in the airways. These data show that thiol drugs inhibit SARS-CoV-2 infection in vitro and reduce SARS-CoV-2-related lung injury in vivo and provide strong rationale for trials of systemically delivered thiol drugs as COVID-19 treatments. We propose that antiviral effects of thiol drugs in vivo will require delivery directly to the airways to ensure millimolar drug concentrations and that thiol drugs with lower thiol pKa values are most likely to be effective.

The effect of cysteamine to decrease SARS-CoV-2 pneumonia in vivo and of multiple thiol drugs to inhibit SARS-CoV-2 infection in vitro provides rationale for clinical trials of thiol drugs in COVID-19.

15LO1 dictates glutathione redox changes in asthmatic airway epithelium to worsen type-2 inflammation

Altered redox biology challenges all cells, with compensatory responses often determining a cell’s fate. When 15 lipoxygenase 1 (15LO1), a lipid-peroxidizing enzyme abundant in asthmatic human airway epithelial cells (HAECs), binds phosphatidylethanolamine-binding protein 1 (PEBP1), hydroperoxy-phospholipids, which drive ferroptotic cell death, are generated. Peroxidases, including glutathione peroxidase 4 (GPX4), metabolize hydroperoxy-phospholipids to hydroxy derivatives to prevent ferroptotic death, but consume reduced glutathione (GSH). The cystine transporter SLC7A11 critically restores/maintains intracellular GSH. We hypothesized that high 15LO1, PEBP1, and GPX4 activity drives abnormal asthmatic redox biology, evidenced by lower bronchoalveolar lavage (BAL) fluid and intraepithelial cell GSH:oxidized GSH (GSSG) ratios, to enhance type 2 (T2) inflammatory responses. GSH, GSSG (enzymatic assays), 15LO1, GPX4, SLC7A11, and T2 biomarkers (Western blot and RNA-Seq) were measured in asthmatic and healthy control (HC) cells and fluids, with siRNA knockdown as appropriate. GSSG was higher and GSH:GSSG lower in asthmatic compared with HC BAL fluid, while intracellular GSH was lower in asthma. In vitro, a T2 cytokine (IL-13) induced 15LO1 generation of hydroperoxy-phospholipids, which lowered intracellular GSH and increased extracellular GSSG. Lowering GSH further by inhibiting SLC7A11 enhanced T2 inflammatory protein expression and ferroptosis. Ex vivo, redox imbalances corresponded to 15LO1 and SLC7A11 expression, T2 biomarkers, and worsened clinical outcomes. Thus, 15LO1 pathway–induced redox biology perturbations worsen T2 inflammation and asthma control, supporting 15LO1 as a therapeutic target.

Quantitative CT metrics are associated with longitudinal lung function decline and future asthma exacerbations: Results from SARP-3

BACKGROUND

Currently, there is limited knowledge regarding which imaging assessments of asthma are associated with accelerated longitudinal decline in lung function.

OBJECTIVES

We aimed to assess whether quantitative computed tomography (qCT) metrics are associated with longitudinal decline in lung function and morbidity in asthma.

METHODS

We analyzed 205 qCT scans of adult patients with asthma and calculated baseline markers of airway remodeling, lung density, and pointwise regional change in lung volume (Jacobian measures) for each participant. Using multivariable regression models, we then assessed the association of qCT measurements with the outcomes of future change in lung function, future exacerbation rate, and changes in validated measurements of morbidity.

RESULTS

Greater baseline wall area percent (β = -0.15 [95% CI = -0.26 to -0.05]; P < .01), hyperinflation percent (β = -0.25 [95% CI = -0.41 to -0.09]; P < .01), and Jacobian gradient measurements (cranial-caudal β = 10.64 [95% CI = 3.79-17.49]; P < .01; posterior-anterior β = -9.14, [95% CI = -15.49 to -2.78]; P < .01) were associated with more severe future lung function decline. Additionally, greater wall area percent (rate ratio = 1.06 [95% CI = 1.01-1.10]; P = .02) and air trapping percent (rate ratio =1.01 [95% CI = 1.00-1.02]; P = .03), as well as lower decline in the Jacobian determinant mean (rate ratio = 0.58 [95% CI = 0.41-0.82]; P < .01) and Jacobian determinant standard deviation (rate ratio = 0.52 [95% CI = 0.32-0.85]; P = .01), were associated with a greater rate of future exacerbations. However, imaging metrics were not associated with clinically meaningful changes in scores on validated asthma morbidity questionnaires.

CONCLUSIONS

Baseline qCT measures of more severe airway remodeling, more small airway disease and hyperinflation, and less pointwise regional change in lung volumes were associated with future lung function decline and asthma exacerbations.

Benefits of Airway Androgen Receptor Expression in Human Asthma

Rationale: Androgens are potentially beneficial in asthma, but AR (androgen receptor) has not been studied in human airways.Objectives: To measure whether AR and its ligands are associated with human asthma outcomes.Methods: We compared the effects of AR expression on lung function, symptom scores, and fractional exhaled nitric oxide (Fe_NO) in adults enrolled in SARP (Severe Asthma Research Program). The impact of sex and of androgens on asthma outcomes was also evaluated in the SARP with validation studies in the Cleveland Clinic Health System and the NHANES (U.S. National Health and Nutrition Examination Survey).Measurements and Main Results: In SARP (n = 128), AR gene expression from bronchoscopic epithelial brushings was positively associated with both FEV₁/FVC ratio (R² = 0.135, P = 0.0002) and the total Asthma Quality of Life Questionnaire score (R² = 0.056, P = 0.016) and was negatively associated with Fe_NO (R² = 0.178, P = 9.8 × 10^-6) and NOS2 (nitric oxide synthase gene) expression (R² = 0.281, P = 1.2 × 10^-10). In SARP (n = 1,659), the Cleveland Clinic Health System (n = 32,527), and the NHANES (n = 2,629), women had more asthma exacerbations and emergency department visits than men. The levels of the AR ligand precursor dehydroepiandrosterone sulfate correlated positively with the FEV₁ in both women and men.Conclusions: Higher bronchial AR expression and higher androgen levels are associated with better lung function, fewer symptoms, and a lower Fe_NO in human asthma. The role of androgens should be considered in asthma management.

PrecISE: Precision Medicine in Severe Asthma: An adaptive platform trial with biomarker ascertainment

Severe asthma accounts for almost half the cost associated with asthma. Severe asthma is driven by heterogeneous molecular mechanisms. Conventional clinical trial design often lacks the power and efficiency to target subgroups with specific pathobiological mechanisms. Furthermore, the validation and approval of new asthma therapies is a lengthy process. A large proportion of that time is taken by clinical trials to validate asthma interventions. The National Institutes of Health Precision Medicine in Severe and/or Exacerbation Prone Asthma (PrecISE) program was established with the goal of designing and executing a trial that uses adaptive design techniques to rapidly evaluate novel interventions in biomarker-defined subgroups of severe asthma, while seeking to refine these biomarker subgroups, and to identify early markers of response to therapy. The novel trial design is an adaptive platform trial conducted under a single master protocol that incorporates precision medicine components. Furthermore, it includes innovative applications of futility analysis, cross-over design with use of shared placebo groups, and early futility analysis to permit more rapid identification of effective interventions. The development and rationale behind the study design are described. The interventions chosen for the initial investigation and the criteria used to identify these interventions are enumerated. The biomarker-based adaptive design and analytic scheme are detailed as well as special considerations involved in the final trial design.

Mixed Sputum Granulocyte Longitudinal Impact on Lung Function in the Severe Asthma Research Program

Rationale: Some reports indicate longitudinal variability in sputum differential cell counts, whereas others describe stability. Highly variable sputum eosinophil percentages are associated with greater lung function loss than persistently elevated eosinophil percentages, but elevated neutrophils are linked to more severe asthma.Objectives: To examine sputum granulocyte stability or variability longitudinally and associations with important clinical characteristics.Methods: The SARP III (Severe Asthma Research Program III) cohort underwent comprehensive phenotype characterization at baseline and annually over 3 years. Adult subjects with acceptable sputum levels were assigned to one of three longitudinal sputum groups: eosinophils predominantly <2%, eosinophils predominantly ≥2%, or highly variable eosinophil percentages (>2 SDs determined from independent, repeated baseline eosinophil percentages). Subjects were similarly assigned to one of three longitudinal neutrophil groups with a 50% cut point.Measurements and Main Results: The group with predominantly <2% sputum eosinophils had the highest lung function (prebronchodilator FEV₁% predicted, P < 0.01; FEV₁/FVC ratio, P < 0.001) at baseline and throughout 3 years compared with other eosinophil groups. Healthcare use did not differ, although the highly variable eosinophil group reported more asthma exacerbations at Year 3. Longitudinal neutrophil groups showed few differences. However, a combination of predominantly ≥2% eosinophil and ≥50% neutrophil groups resulted in the lowest prebronchodilator FEV₁% predicted (P = 0.049) compared with the combination with predominantly <2% eosinophils and<50% neutrophils.Conclusions: Subjects with predominantly ≥2% sputum eosinophils in combination with predominantly ≥50% neutrophils showed greater loss of lung function, whereas those with highly variable sputum eosinophils had greater healthcare use.

Responsiveness to Parenteral Corticosteroids and Lung Function Trajectory in Adults with Moderate-to-Severe Asthma

Rationale: It is unclear why select patients with moderate-to-severe asthma continue to lose lung function despite therapy. We hypothesized that participants with the smallest responses to parenteral corticosteroids have the greatest risk of undergoing a severe decline in lung function.Objectives: To evaluate corticosteroid-response phenotypes as longitudinal predictors of lung decline.Methods: Adults within the NHLBI SARP III (Severe Asthma Research Program III) who had undergone a course of intramuscular triamcinolone at baseline and at ≥2 annual follow-up visits were evaluated. Longitudinal slopes were calculated for each participant's post-bronchodilator FEV₁% predicted. Categories of participant FEV₁ slope were defined: severe decline, >2% loss/yr; mild decline, >0.5-2.0% loss/yr; no change, 0.5% loss/yr to <1% gain/yr; and improvement, ≥1% gain/yr. Regression models were used to develop predictors of severe decline.Measurements and Main Results: Of 396 participants, 78 had severe decline, 91 had mild decline, 114 had no change, and 113 showed improvement. The triamcinolone-induced difference in the post-bronchodilator FEV₁% predicted (derived by baseline subtraction) was related to the 4-year change in lung function or slope category in univariable models (P < 0.001). For each 5% decrement in the triamcinolone-induced difference the FEV1% predicted, there was a 50% increase in the odds of being in the severe decline group (odds ratio, 1.5; 95% confidence interval, 1.3-1.8), when adjusted for baseline FEV₁, exacerbation history, blood eosinophils and body mass index.Conclusions: Failure to improve the post-bronchodilator FEV₁ after a challenge with parenteral corticosteroids is an evoked biomarker for patients at risk for a severe decline in lung function.

Genetic and non-genetic factors affecting the expression of COVID-19-relevant genes in the large airway epithelium

BACKGROUND

The large airway epithelial barrier provides one of the first lines of defense against respiratory viruses, including SARS-CoV-2 that causes COVID-19. Substantial inter-individual variability in individual disease courses is hypothesized to be partially mediated by the differential regulation of the genes that interact with the SARS-CoV-2 virus or are involved in the subsequent host response. Here, we comprehensively investigated non-genetic and genetic factors influencing COVID-19-relevant bronchial epithelial gene expression.

METHODS

We analyzed RNA-sequencing data from bronchial epithelial brushings obtained from uninfected individuals. We related ACE2 gene expression to host and environmental factors in the SPIROMICS cohort of smokers with and without chronic obstructive pulmonary disease (COPD) and replicated these associations in two asthma cohorts, SARP and MAST. To identify airway biology beyond ACE2 binding that may contribute to increased susceptibility, we used gene set enrichment analyses to determine if gene expression changes indicative of a suppressed airway immune response observed early in SARS-CoV-2 infection are also observed in association with host factors. To identify host genetic variants affecting COVID-19 susceptibility in SPIROMICS, we performed expression quantitative trait (eQTL) mapping and investigated the phenotypic associations of the eQTL variants.

RESULTS

We found that ACE2 expression was higher in relation to active smoking, obesity, and hypertension that are known risk factors of COVID-19 severity, while an association with interferon-related inflammation was driven by the truncated, non-binding ACE2 isoform. We discovered that expression patterns of a suppressed airway immune response to early SARS-CoV-2 infection, compared to other viruses, are similar to patterns associated with obesity, hypertension, and cardiovascular disease, which may thus contribute to a COVID-19-susceptible airway environment. eQTL mapping identified regulatory variants for genes implicated in COVID-19, some of which had pheWAS evidence for their potential role in respiratory infections.

CONCLUSIONS

These data provide evidence that clinically relevant variation in the expression of COVID-19-related genes is associated with host factors, environmental exposures, and likely host genetic variation.

Mucus Plugs and Emphysema in the Pathophysiology of Airflow Obstruction and Hypoxemia in Smokers

Rationale: The relative roles of mucus plugs and emphysema in mechanisms of airflow limitation and hypoxemia in smokers with chronic obstructive pulmonary disease (COPD) are uncertain.Objectives: To relate image-based measures of mucus plugs and emphysema to measures of airflow obstruction and oxygenation in patients with COPD.Methods: We analyzed computed tomographic (CT) lung images and lung function in participants in the Subpopulations and Intermediate Outcome Measures in COPD Study. Radiologists scored mucus plugs on CT lung images, and imaging software automatically quantified emphysema percentage. Unadjusted and adjusted relationships between mucus plug score, emphysema percentage, and lung function were determined using regression.Measurements and Main Results: Among 400 smokers, 229 (57%) had mucus plugs and 207 (52%) had emphysema, and subgroups could be identified with mucus-dominant and emphysema-dominant disease. Only 33% of smokers with high mucus plug scores had mucus symptoms. Mucus plug score and emphysema percentage were independently associated with lower values for FEV1 and peripheral oxygen saturation (P < 0.001). The relationships between mucus plug score and lung function outcomes were strongest in smokers with limited emphysema (P < 0.001). Compared with smokers with low mucus plug scores, those with high scores had worse COPD Assessment Test scores (17.4 ± 7.7 vs. 14.4 ± 13.3), more frequent annual exacerbations (0.75 ± 1.1 vs. 0.43 ± 0.85), and shorter 6-minute-walk distance (329 ± 115 vs. 392 ± 117 m) (P < 0.001).Conclusions: Symptomatically silent mucus plugs are highly prevalent in smokers and independently associate with lung function outcomes. These data provide rationale for targeting patients with mucus-high/emphysema-low COPD in clinical trials of mucoactive treatments.Clinical trial registered with www.clinicaltrials.gov (NCT01969344).

The Use of a Three-Fluid Atomising Nozzle in the Production of Spray-Dried Theophylline/Salbutamol Sulphate Powders Intended for Pulmonary Delivery

The aim of this study was to investigate the use of a three-fluid atomising nozzle in a lab-scale spray dryer for the production of dry powders intended for pulmonary delivery. Powders were composed of salbutamol sulphate and theophylline in different weight ratios. The three-fluid nozzle technology enabled powders containing a high theophylline content to be obtained, overcoming the problems associated with its relatively low solubility, by pumping two separate feed solutions (containing the two different active pharmaceutical ingredients (APIs)) into the spray dryer via two separate nozzle channels at different feed rates. The final spray-dried products were characterized in terms of morphology, solid-state properties and aerosolization performance, and were compared with an equivalent formulation prepared using a standard two-fluid atomising nozzle. Results confirmed that most of the powders made using the three-fluid atomising nozzle met the required standards for a dry powder inhaler formulation in terms of physical characteristics; however, aerosolization characteristics require improvement if the powders are to be considered suitable for pulmonary delivery.

The precision interventions for severe and/or exacerbation-prone asthma (PrecISE) adaptive platform trial: statistical considerations

The Precision Interventions for Severe and/or Exacerbation-prone Asthma (PrecISE) study is an adaptive platform trial designed to investigate novel interventions to severe asthma. The study is conducted under a master protocol and utilizes a crossover design with each participant receiving up to five interventions and at least one placebo. Treatment assignments are based on the patients' biomarker profiles and precision health methods are incorporated into the interim and final analyses. We describe key elements of the PrecISE study including the multistage adaptive enrichment strategy, early stopping of an intervention for futility, power calculations, and the primary analysis strategy.

Evidence for Exacerbation-Prone Asthma and Predictive Biomarkers of Exacerbation Frequency

Rationale: Cross-sectional studies suggest an exacerbation-prone asthma (EPA) phenotype and the utility of blood eosinophils and plasma IL-6 as predictive biomarkers.Objectives: To prospectively test for EPA phenotype and utility of baseline blood measures of eosinophils and IL-6 as predictive biomarkers.Methods: Three-year asthma exacerbation data were analyzed in 406 adults in the Severe Asthma Research Program-3. Transition models were used to assess uninformed and informed probabilities of exacerbation in year 3. Binomial regression models were used to assess eosinophils and IL-6 as predictive biomarkers.Measurements and Main Results: Eighty-three participants (21%) had ≥1 exacerbation in each year (EPA) and 168 participants (41%) had no exacerbation in any year (exacerbation-resistant asthma). The uninformed probability of an exacerbation in Year 3 was 40%, but the informed probability increased to 63% with an exacerbation in Year 2 and 82% with an exacerbation in Years 1 and 2. The probability of a Year 3 exacerbation with no Year 1 or 2 exacerbations was 13%. Compared with exacerbation-resistant asthma, EPA was characterized by lower FEV₁ and a higher prevalence of obesity, hypertension, and diabetes. High-plasma IL-6 occurred in EPA, and the incident rate ratio for exacerbation increased 10% for each 1-pg/μl increase in baseline IL-6 level. Although high blood eosinophils did not occur in EPA, the incident rate ratio for exacerbations increased 9% for each 100-cell/μl increase in baseline eosinophil number.Conclusions: Longitudinal analysis confirms an EPA phenotype characterized by features of metabolic dysfunction. Blood measures of IL-6, but not eosinophils, were significantly associated with EPA, and IL-6 and eosinophils predicted exacerbations in the sample as a whole.

An anti-siglec-8 antibody depletes sputum eosinophils from asthmatic subjects and inhibits lung mast cells

BACKGROUND

Sialic acid-binding immunoglobulin-like lectin (Siglec)-8 is expressed on mast cells and eosinophils, but information about Siglec-8 expression and function in the lung is limited. A humanized antibody, AK002, targeting Siglec-8 is undergoing development for treatment of diseases associated with mast cell and eosinophil-driven inflammation.

OBJECTIVE

To characterize Siglec-8 expression in the airway in asthma and determine whether antibodies that target Siglec-8 (S8mAbs) can decrease airway eosinophils in asthma or inhibit lung mast cell activation.

METHODS

Gene expression profiling and flow cytometry were used to characterize Siglec-8 expression in sputum cells from stable asthma. An antibody-dependent cellular cytotoxicity (ADCC) assay was used to determine whether an S8mAb can decrease eosinophils in sputum from asthma patients ex vivo. A mast cell activation assay was used to determine whether an S8mAb can inhibit mast cell activation in human lung tissue ex vivo.

RESULTS

Gene expression for Siglec-8 is increased in sputum cells in asthma and correlates with gene expression for eosinophils and mast cells. Gene expression for Siglec-8 is inversely and significantly correlated with measures of airflow obstruction in asthma patients. Siglec-8 is prominently expressed on the surface of eosinophils and mast cells in sputum. S8mAbs decrease eosinophils in sputum from patients with asthma and inhibit FcεR1-activated mast cells in lung tissues.

CONCLUSIONS AND CLINICAL RELEVANCE

Siglec-8 is highly expressed on eosinophils and mast cells in asthmatic sputum and targeting Siglec-8 with an antibody is a plausible strategy to decrease sputum eosinophils and inhibit lung mast cells in asthma.

An Allosteric Anti-tryptase Antibody for the Treatment of Mast Cell-Mediated Severe Asthma

Severe asthma patients with low type 2 inflammation derive less clinical benefit from therapies targeting type 2 cytokines and represent an unmet need. We show that mast cell tryptase is elevated in severe asthma patients independent of type 2 biomarker status. Active β-tryptase allele count correlates with blood tryptase levels, and asthma patients carrying more active alleles benefit less from anti-IgE treatment. We generated a noncompetitive inhibitory antibody against human β-tryptase, which dissociates active tetramers into inactive monomers. A 2.15 Å crystal structure of a β-tryptase/antibody complex coupled with biochemical studies reveal the molecular basis for allosteric destabilization of small and large interfaces required for tetramerization. This anti-tryptase antibody potently blocks tryptase enzymatic activity in a humanized mouse model, reducing IgE-mediated systemic anaphylaxis, and inhibits airway tryptase in Ascaris-sensitized cynomolgus monkeys with favorable pharmacokinetics. These data provide a foundation for developing anti-tryptase as a clinical therapy for severe asthma.

HSD3B1 genotype identifies glucocorticoid responsiveness in severe asthma

Asthma resistance to glucocorticoid treatment is a major health problem with unclear etiology. Glucocorticoids inhibit adrenal androgen production. However, androgens have potential benefits in asthma. HSD3B1 encodes for 3β-hydroxysteroid dehydrogenase-1 (3β-HSD1), which catalyzes peripheral conversion from adrenal dehydroepiandrosterone (DHEA) to potent androgens and has a germline missense-encoding polymorphism. The adrenal restrictive HSD3B1(1245A) allele limits conversion, whereas the adrenal permissive HSD3B1(1245C) allele increases DHEA metabolism to potent androgens. In the Severe Asthma Research Program (SARP) III cohort, we determined the association between DHEA-sulfate and percentage predicted forced expiratory volume in 1 s (FEV1PP). HSD3B1(1245) genotypes were assessed, and association between adrenal restrictive and adrenal permissive alleles and FEV1PP in patients with (GC) and without (noGC) daily oral glucocorticoid treatment was determined (n = 318). Validation was performed in a second cohort (SARP I&II; n = 184). DHEA-sulfate is associated with FEV1PP and is suppressed with GC treatment. GC patients homozygous for the adrenal restrictive genotype have lower FEV1PP compared with noGC patients (54.3% vs. 75.1%; P < 0.001). In patients with the homozygous adrenal permissive genotype, there was no FEV1PP difference in GC vs. noGC patients (73.4% vs. 78.9%; P = 0.39). Results were independently confirmed: FEV1PP for homozygous adrenal restrictive genotype in GC vs. noGC is 49.8 vs. 63.4 (P < 0.001), and for homozygous adrenal permissive genotype, it is 66.7 vs. 67.7 (P = 0.92). The adrenal restrictive HSD3B1(1245) genotype is associated with GC resistance. This effect appears to be driven by GC suppression of 3β-HSD1 substrate. Our results suggest opportunities for prediction of GC resistance and pharmacologic intervention.

Investigation of the relationship between IL-6 and type 2 biomarkers in patients with severe asthma

Combination of IL-6 (non-Type 2 asthma) and FeNO or blood eosinophil count (Type 2 asthma) identified asthma endotypes related to asthma severity, exacerbations, and responsiveness to corticosteroids and potential for response to anti-Type 2 and anti-IL-6 treatment.

Clinical significance of the bronchodilator response in children with severe asthma

BACKGROUND

Our objective was to determine those characteristics associated with reversibility of airflow obstruction and response to maximal bronchodilation in children with severe asthma through the Severe Asthma Research Program (SARP).

METHODS

We performed a cross-sectional analysis evaluating children ages 6 to 17 years with nonsevere asthma (NSA) and severe asthma (SA). Participants underwent spirometry before and after 180 µg of albuterol to determine reversibility (≥12% increase in FEV₁ ). Participants were then given escalating doses up to 720 µg of albuterol to determine their maximum reversibility.

RESULTS

We evaluated 230 children (n = 129 SA, n = 101 NSA) from five centers across the United States in the SARP I and II cohorts. SA (odds ratio [OR], 2.08, 95% confidence interval [CI], 1.05-4.13), second-hand smoke exposure (OR, 2.81, 95%CI, 1.23-6.43), and fractional exhaled nitric oxide (FeNO; OR, 1.97, 95%CI, 1.35-2.87) were associated with increased odds of airway reversibility after maximal bronchodilation, while higher prebronchodilator (BD) FEV₁ % predicted (OR, 0.91, 95%CI, 0.88-0.94) was associated with decreased odds. In an analysis using the SARP III cohort (n = 186), blood neutrophils, immunoglobulin E (IgE), and FEV₁ % predicted were significantly associated with BD reversibility. In addition, children with BD response have greater healthcare utilization. BD reversibility was associated with reduced lung function at enrollment and 1-year follow-up though less decline in lung function over 1 year compared to those without reversibility.

CONCLUSIONS

Lung function, that is FEV₁ % predicted, is a predictor of BD response in children with asthma. Additionally, smoke exposure, higher FeNO or IgE level, and low peripheral blood neutrophils are associated with a greater likelihood of BD reversibility. BD response can identify a phenotype of pediatric asthma associated with low lung function and poor asthma control.

Neutrophil cytoplasts induce TH17 differentiation and skew inflammation toward neutrophilia in severe asthma

Severe asthma is a debilitating and treatment refractory disease. As many as half of these patients have complex neutrophil-predominant lung inflammation that is distinct from milder asthma with type 2 eosinophilic inflammation. New insights into severe asthma pathogenesis are needed. Concomitant exposure of mice to an aeroallergen and endotoxin during sensitization resulted in complex neutrophilic immune responses to allergen alone during later airway challenge. Unlike allergen alone, sensitization with allergen and endotoxin led to NETosis. In addition to neutrophil extracellular traps (NETs), enucleated neutrophil cytoplasts were evident in the lungs. Surprisingly, allergen-driven airway neutrophilia was decreased in peptidyl arginine deiminase 4-deficient mice with defective NETosis but not by deoxyribonuclease treatment, implicating the cytoplasts for the non-type 2 immune responses to allergen. Neutrophil cytoplasts were also present in mediastinal lymph nodes, and the cytoplasts activated lung dendritic cells in vitro to trigger antigen-specific interleukin-17 (IL-17) production from naïve CD4⁺ T cells. Bronchoalveolar lavage fluid from patients with severe asthma and high neutrophil counts had detectable NETs and cytoplasts that were positively correlated with IL-17 levels. Together, these translational findings have identified neutrophil cytoplast formation in asthmatic lung inflammation and linked the cytoplasts to T helper 17-mediated neutrophilic inflammation in severe asthma.

Severe asthma during childhood and adolescence: A longitudinal study

BACKGROUND

Morbidity and mortality associated with childhood asthma are driven disproportionately by children with severe asthma. However, it is not known from longitudinal studies whether children outgrow severe asthma.

OBJECTIVE

We sought to study prospectively whether well-characterized children with severe asthma outgrow their asthma during adolescence.

METHODS

Children with asthma were assessed at baseline with detailed questionnaires, allergy tests, and lung function tests and were reassessed annually for 3 years. The population was enriched for children with severe asthma, as assessed by the American Thoracic Society/European Respiratory Society guidelines, and subject classification was reassessed annually.

RESULTS

At baseline, 111 (59%) children had severe asthma. Year to year, there was a decrease in the proportion meeting the criteria for severe asthma. After 3 years, only 30% of subjects met the criteria for severe asthma (P < .001 compared with enrollment). Subjects experienced improvements in most indices of severity, including symptom scores, exacerbations, and controller medication requirements, but not lung function. Surprisingly, boys and girls were equally likely to has resolved asthma (33% vs 29%). The odds ratio in favor of resolution of severe asthma was 2.75 (95% CI, 1.02-7.43) for those with a peripheral eosinophil count of greater than 436 cells/μL.

CONCLUSIONS

In longitudinal analysis of this well-characterized cohort, half of the children with severe asthma no longer had severe asthma after 3 years; there was a stepwise decrease in the proportion meeting severe asthma criteria. Surprisingly, asthma severity decreased equally in male and female subjects. Peripheral eosinophilia predicted resolution. These data will be important for planning clinical trials in this population.

Development and initial validation of the Asthma Severity Scoring System (ASSESS)

BACKGROUND

Tools for quantification of asthma severity are limited.

OBJECTIVE

We sought to develop a continuous measure of asthma severity, the Asthma Severity Scoring System (ASSESS), for adolescents and adults, incorporating domains of asthma control, lung function, medications, and exacerbations.

METHODS

Baseline and 36-month longitudinal data from participants in phase 3 of the Severe Asthma Research Program (NCT01606826) were used. Scale properties, responsiveness, and a minimally important difference were determined. External replication was performed in participants enrolled in the Severe Asthma Research Program phase 1/2. The utility of ASSESS for detecting treatment response was explored in participants undergoing corticosteroid responsiveness testing with intramuscular triamcinolone and participants receiving biologics.

RESULTS

ASSESS scores ranged from 0 to 20 (8.78 ± 3.9; greater scores reflect worse severity) and differed among 5 phenotypic groups. Measurement properties were acceptable. ASSESS was responsive to changes in quality of life with a minimally important difference of 2, with good specificity for outcomes of asthma improvement and worsening but poor sensitivity. Replication analyses yielded similar results, with a 2-point decrease (improvement) associated with improvements in quality of life. Participants with a 2-point or greater decrease (improvement) in ASSESS scores also had greater improvement in lung function and asthma control after triamcinolone, but these differences were limited to phenotypic clusters 3, 4, and 5. Participants treated with biologics also had a 2-point or greater decrease (improvement) in ASSESS scores overall.

CONCLUSIONS

The ASSESS tool is an objective measure that might be useful in epidemiologic and clinical research studies for quantification of treatment response in individual patients and phenotypic groups. However, validation studies are warranted.

The use of hydrophobic amino acids in protecting spray dried trehalose formulations against moisture-induced changes

Trehalose is commonly used as a protein stabilizer in spray dried protein formulations delivered via the pulmonary route. Spray dried trehalose formulations are highly hygroscopic, which makes them prone to deliquescence and recrystallization when exposed to moisture, leading to impairment in aerosolization performance. The main aim of this study was to investigate and compare the effect of hydrophobic amino acids (i.e. L-leucine and L-isoleucine) in enhancing aerosolization performance and in mitigating moisture-induced changes in spray dried trehalose formulations. Trehalose was spray dried with 20-60% w/w of amino acid (i.e. L-leucine or L-isoleucine). The spray dried formulations were stored at 25 °C/50% RH for 28 days. Solid state characterization and in vitro aerosolization performance studies were performed on the spray dried formulations before and after storage. The addition of 20-60% w/w of amino acid (i.e. L-leucine or L-isoleucine) improved the emitted fractions of spray dried trehalose formulations from a dry powder inhaler. However, ≥ 40% w/w of L-leucine/L-isoleucine was needed to prevent recrystallization of trehalose in the formulations when exposed to 25 °C/50% RH for 28 days. X-ray photoelectron spectroscopy (XPS) demonstrated that samples with 40-60% w/w L-isoleucine had more amino acid on the surfaces of the particles compared to their L-leucine counterparts. This may explain the greater ability of the L-isoleucine (40-60% w/w) samples to cope with elevated humidity compared to L-leucine samples of the same concentrations, as observed in the dynamic vapour sorption (DVS) studies. In conclusion, this study demonstrated that both L-leucine and L-isoleucine were effective in enhancing aerosolization performance and mitigating moisture-induced reduction in aerosolization performance in spray dried trehalose formulations. L-isoleucine proved to be superior to L-leucine in terms of its moisture protectant effect when incorporated at the same concentration in the formulations.