Inflammatory Phenotypes Of Asthma Research Articles

Characteristic DNA methylation profiles in peripheral blood monocytes are associated with inflammatory phenotypes of asthma

Epigenetic changes including DNA methylation caused by environmental exposures may contribute to the heterogeneous inflammatory response in asthma. Here we investigate alterations in DNA methylation of purified blood monocytes that are associated with inflammatory phenotypes of asthma. Peripheral blood was collected from adults with eosinophilic asthma (EA; n = 21), paucigranulocytic asthma (PGA; n = 22), neutrophilic asthma (NA; n = 9), and healthy controls (n = 10). Blood monocytes were isolated using ficoll density gradient and immuno-magnetic cell separation. Bisulfite converted genomic DNA was hybridized to Illumina Infinium Methylation27 arrays and analyzed for differential methylation using R/Bioconductor packages; networks of gene interactions were identified using the STRING database. Compared with healthy controls, differentially methylated CpG loci were identified in EA (n = 413), PGA (n = 495), and NA (n = 89). We found that 223, 237, and 72 loci were significantly hypermethylated in EA, PGA, and NA, respectively. Nine genes were common to all three phenotypes and showed increased methylation in asthma. Three pathway networks were identified in EA, involved in purine metabolism, calcium signaling, and ECM-receptor interaction. In PGA, two networks were identified, involved in neuroactive ligand-receptor interaction and ubiquitin mediated proteolysis. In NA, one network was identified involving sFRP1 as a key node, over representing the Wnt signaling pathway. We have identified characteristic alterations in DNA methylation that are associated with inflammatory phenotypes of asthma and may contribute to the disease mechanisms. This network-based characterization may help in the development of epigenetic biomarkers and therapeutic targets for asthma.

Comprehensive multiplexed protein quantitation delineates eosinophilic and neutrophilic experimental asthma.

BackgroundImprovements in asthma diagnosis and management require deeper understanding of the heterogeneity of the complex airway inflammation. We hypothesise that differences in the two major inflammatory phenotypes of asthma; eosinophilic and neutrophilic asthma, will be reflected in the lung protein expression profile of murine asthma models and can be delineated using proteomics of bronchoalveolar lavage (BAL).MethodsBAL from mice challenged with ovalbumin (OVA/OVA) alone (standard model of asthma, here considered eosinophilic) or OVA in combination with endotoxin (OVA/LPS, model of neutrophilic asthma) was analysed using liquid chromatography coupled to high resolution mass spectrometry, and compared with steroid-treated animals and healthy controls. In addition, conventional inflammatory markers were analysed using multiplexed ELISA (Bio-Plex™ assay). Multivariate statistics was performed on integrative proteomic fingerprints using principal component analysis. Proteomic data were complemented with lung mechanics and BAL cell counts.ResultsSeveral of the analysed proteins displayed significant differences between the controls and either or both of the two models reflecting eosinophilic and neutrophilic asthma. Most of the proteins found with mass spectrometry analysis displayed a considerable increase in neutrophilic asthma compared with the other groups. Conversely, the larger number of the inflammatory markers analysed with Bio-Plex™ analysis were found to be increased in the eosinophilic model. In addition, major inflammation markers were correlated to peripheral airway closure, while commonly used asthma biomarkers only reflect central inflammation.ConclusionOur data suggest that the commercial markers we are currently relying on to diagnose asthma subtypes are not giving us comprehensive or specific enough information. The analysed protein profiles allowed to discriminate the two models and may add useful information for characterization of different asthma phenotypes.

Sputum gene expression signature of 6 biomarkers discriminates asthma inflammatory phenotypes

Airway inflammation is associated with asthma exacerbation risk, treatment response, and disease mechanisms. This study aimed to identify and validate a sputum gene expression signature that discriminates asthma inflammatory phenotypes. An asthma phenotype biomarker discovery study generated gene expression profiles from induced sputum of 47 asthmatic patients. A clinical validation study (n = 59 asthmatic patients) confirmed differential expression of key genes. A 6-gene signature was identified and evaluated for reproducibility (n = 30 asthmatic patients and n = 20 control subjects) and prediction of inhaled corticosteroid (ICS) response (n = 71 asthmatic patients). Receiver operating characteristic curves were calculated, and area under the curve (AUC) values were reported. From 277 differentially expressed genes between asthma inflammatory phenotypes, we identified 23 genes that showed highly significant differential expression in both the discovery and validation populations. A signature of 6 genes, including Charcot-Leydon crystal protein (CLC); carboxypeptidase A3 (CPA3); deoxyribonuclease I-like 3 (DNASE1L3); IL-1β (IL1B); alkaline phosphatase, tissue-nonspecific isozyme (ALPL); and chemokine (C-X-C motif) receptor 2 (CXCR2), was reproducible and could significantly (P < .0001) discriminate eosinophilic asthma from other phenotypes, including patients with noneosinophilic asthma (AUC, 89.6%), paucigranulocytic asthma (AUC, 92.6%), or neutrophilic asthma (AUC, 91.4%) and healthy control subjects (AUC, 97.6%), as well as discriminating patients with neutrophilic asthma from those with paucigranulocytic asthma (AUC, 85.7%) and healthy control subjects (AUC, 90.8). The 6-gene signature predicted ICS response (>12% change in FEV1; AUC, 91.5%). ICS treatment reduced the expression of CLC, CPA3, and DNASE1L3 in patients with eosinophilic asthma. A sputum gene expression signature of 6 biomarkers reproducibly and significantly discriminates inflammatory phenotypes of asthma and predicts ICS treatment response. This signature has the potential to become a useful diagnostic tool to assist in the clinical diagnosis and management of asthma.

Sputum ADAM8 expression is increased in severe asthma and COPD

Severe asthma and chronic obstructive pulmonary disease (COPD) are chronic inflammatory airway diseases in which the mechanisms are not fully understood. A disintegrin and metalloproteinase domain 8 (ADAM8) is an enzyme expressed on most leucocytes and may be important for facilitating leucocyte migration in respiratory disease. To investigate ADAM8 mRNA and protein expression in asthma and COPD and its relationship between asthma severity and inflammatory phenotypes. Induced sputum was collected from 113 subjects with asthma (severe n=31, uncontrolled n=39 and controlled n=35), 20 subjects with COPD and 21 healthy controls. Sputum ADAM8 mRNA expression was measured by qPCR, and soluble ADAM8 (sADAM8) protein was measured in the sputum supernatant by validated ELISA. ADAM8 mRNA correlated with ADAM8 protein levels (r=0.27, P<0.01). ADAM8 mRNA (P=0.004) and sADAM8 protein (P=0.014) levels were significantly higher in both asthma and COPD compared with healthy controls. ADAM8 mRNA (P=0.035) and sADAM8 protein (P=0.002) levels were significantly higher in severe asthma compared with controlled asthma. Total inflammatory cell count (P<0.01) and neutrophils (P<0.01) were also elevated in severe asthmatic sputum. Although ADAM8 mRNA was significantly higher in eosinophilic and neutrophilic asthma (P<0.001), sADAM8 did not differ between asthma inflammatory phenotypes. ADAM8 expression positively correlated with sputum total cell count and sputum neutrophils. ADAM8 expression is increased in both severe asthma and COPD and associated with sputum total cell count and neutrophils. ADAM8 may facilitate neutrophil migration to the airways in severe asthma and COPD.

Anti-Viral Innate Immunity Varies Across Different Asthma Inflammatory Phenotypes

Anti-Viral Innate Immunity Varies Across Different Asthma Inflammatory Phenotypes

Activity and expression of histone acetylases and deacetylases in inflammatory phenotypes of asthma

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) regulate gene expression, yet differences in the activity of these enzymes in the inflammatory phenotypes of asthma are unknown. We hypothesized that neutrophilic asthma (NA) would be associated with increased HAT and decreased HDAC activity. To investigate total HAT/HDAC activity and gene expression in isolated blood monocytes and sputum macrophages from healthy and patients with asthma. Peripheral blood and induced sputum were collected from adults with asthma (n = 52) and healthy controls (n = 9). Sputum inflammatory cell counts were performed and asthma inflammatory phenotypes were classified according to sputum eosinophil and neutrophil cut-off's of > 3% and > 61% respectively. Peripheral blood monocytes were isolated (n = 61) and sputum macrophages were isolated from a subgroup of patients with asthma (n = 14), using immunomagnetic cell separation. RNA and nuclear proteins were extracted and quantified. Enzyme activity was assessed using fluorescent assays and gene expression of EP300, KAT2B, CREBBP, and HDACs 1, 2 and 3 were measured by qPCR. There was a significant inverse association between blood monocyte HAT and HDAC activity (r = -0.58, P < 0.001). NA was associated with increased blood monocyte HAT enzyme activity (P = 0.02), decreased HDAC activity (P = 0.03), and increased HAT: HDAC ratio (P < 0.01) compared with eosinophilic asthma. There were no differences in gene expression of EP300, KAT2B, CREBBP, or HDACs 1, 2 and 3 in blood monocytes from subjects with asthma or inflammatory phenotypes of asthma. There was no effect of inhaled corticosteroid use, poor asthma control, or asthma severity on HAT/HDAC activities. Sputum macrophages had increased expression of KAT2B in eosinophilic compared with paucigranulocytic asthma. Neutrophilic airway inflammation is associated with increased HAT and reduced HDAC activity in blood monocytes, demonstrating further systemic manifestations relating to the altered inflammatory gene transcription profile of neutrophilic asthma.

Identification of inflammatory phenotypes of asthma by blood analysis and clinical parameters

Background Identification of an inflammatory asthma phenotype currently requires sputum induction. This technique is invasive, has a high variability, is time-consuming and a burden for patients. Therefore, there is a strong need for a routine blood test to establish the inflammatory phenotype of asthma. We designed a clinical cohort study (AIR-study, NCT01611012) in 115 asthma patients visiting the outpatient clinic to compare the results of such a blood test to sputum analysis. This abstracts focuses at the preliminary results in 21 patients.

Inhaled Corticosteroid Dose Response Using Domiciliary Exhaled Nitric Oxide in Persistent Asthma: The Fenotype Trial

International guidelines advocate a standard approach to asthma management for all, despite its heterogeneity. "Personalized" treatment of inflammatory asthma phenotypes confers superior benefits. We wished to evaluate dose response to inhaled corticosteroids (ICSs) in patients with asthma with an elevated fractional exhaled nitric oxide (Feno) phenotype using domiciliary measurements.We performed a randomized, crossover trial in 21 patients with mild to moderate persistent asthma receiving ICSs with elevated Feno (>30 parts per billion [ppb]) that increased further (>10 ppb) after ICS washout. Patients were randomized to 2 weeks of either fluticasone propionate 50 μg bid (FP100) or 250 μg bid (FP500). The primary outcome was response in diurnal domiciliary Feno levels. Secondary outcomes included mannitol challenge, serum eosinophilic cationic protein (ECP), blood eosinophil count, and asthma control questionnaire.We found significant dose-related reductions of diurnal Feno compared with baseline - morning Feno: baseline = 71 ppb (95% CI, 61-83 ppb); FP100 = 34 ppb (95% CI, 29-40 ppb), P < .001; FP500 = 27 ppb (95% CI, 22-33 ppb), P < .001; and significant dose separation for morning, P < .05, and evening, P < .001. Time-series Feno displayed exponential decay: FP100 R² = 0.913, half-life = 69 h (95% CI, 50-114 h); FP500 R² = 0.966, half-life = 55 h (95% CI, 45-69 h), as well as diurnal variation. The Asthma Control Questionnaire showed significant improvements exceeding the minimal important difference (>0.5) with values in keeping with controlled asthma (<0.75) after each dose: FP100 = 0.48 (95% CI, 0.24-0.71), P = .004; FP500 = 0.37 (95% CI, 0.18-0.57), P = .001. All other secondary inflammatory related outcomes (mannitol, ECP, and eosinophils) showed significant improvements from baseline but no dose separation.There is a significant dose response of diurnal Feno to ICS in patients with asthma with an elevated Feno phenotype, which translates into well-controlled asthma. Further interventional studies are warranted using domiciliary Feno in this specific phenotype.ClinicalTrials.gov; No.: NCT00995657; URL: clinicaltrials.gov.

S6 The FENOtype Trial: Inhaled Corticosteroid Dose-Response Using Domiciliary Exhaled Nitric Oxide in Persistent Asthma

Background International guidelines advocate a standard approach to asthma management for all despite its heterogeneity. ‘Personalised’ treatment for inflammatory asthma phenotypes confers superior benefits. We wished to evaluate dose-response to inhaled corticosteroids (ICS) in asthmatics with an elevated exhaled nitric oxide (FeNO) phenotype using domiciliary measurements. Methods We performed a randomised, cross-over trial in 21 mild-to-moderate persistent asthmatics receiving ICS with elevated FeNO (>30ppb) that increased further (>10ppb) after ICS washout. Patients were randomised to 2 weeks of either fluticasone propionate 50µg twice-daily (FP100) or 250µg twice-daily (FP500). The primary outcome was response in diurnal domiciliary FeNO levels. Secondary outcomes included: mannitol challenge; serum eosinophilic cationic protein (ECP); blood eosinophil count; and asthma control questionnaire (ACQ). Results We found significant dose-related reductions of diurnal FeNO compared to baseline - morning FeNO: baseline=71ppb (95%CI:61–83ppb); FP100=34ppb (95%CI:29–40ppb), p 0.5) with values in keeping with controlled asthma ( Conclusions There is a significant dose-response of diurnal FeNO to ICS in asthmatics with an elevated FeNO phenotype, which translates into well-controlled asthma. Further interventional studies are warranted using domiciliary FeNO in this specific phenotype.

Obesity and asthma disease phenotypes

The increasing prevalence of both asthma and obesity is associated with substantial morbidity and healthcare utilization. Herein, we review recent data suggesting that the obese asthmatic may represent a distinct clinical phenotype. Obesity is a major risk factor for asthma, and asthma in obese patients appears to be more difficult to control, with decreased responsiveness to controller therapies posing a significant public health issue, as the prevalence of both asthma and obesity continues to rise. Epidemiologic research has defined the association between obesity and asthma, an association in part influenced by physiologic abnormalities attendant to both disorders. Healthcare utilization is also increased in obese asthmatic individuals, with reduced response to asthma controller therapies, a finding likely mediated by specific aspects of systemic and airway inflammation. We end by reviewing the role of comorbid clinical disorders in the association and by highlighting evidence that weight loss is associated with improvement in clinical and physiologic parameters of asthma. Obesity has a significant impact on asthma risk, severity and control. Additional studies are needed to define mechanisms by which airway physiologic and inflammatory phenotypes in asthma are modified by obesity.

Profiling of Sputum Inflammatory Mediators in Asthma and Chronic Obstructive Pulmonary Disease

Background: Asthma and chronic obstructive pulmonary disease (COPD) display features of overlap in airway physiology and airway inflammation. Whether inflammatory phenotypes in airway disease describe similar mediator expression is unknown. Objectives: To explore the relationship of airway inflammation and cytokine and chemokine expression in asthma and COPD. Methods: Subjects with asthma and COPD (n = 54 and n = 49) were studied. Clinical characteristics and sputum were collected at entry into the study. A 2-step sputum processing method was performed for supernatant and cytospin preparation. Meso Scale Discovery and Luminex platforms were used to measure cytokines, chemokines and matrix metalloproteinase levels. Results: Analytes sensitive to dithiothreitol (DTT) that had increased recovery in the 2-step sputum process were IL-1β, 4, 5, 10, 13, IFN-γ, TNFRI, GM-CSF, CCL2, 3, 4, 5, 13 and 17. There was a differential expression in IL-8, TNFRI and TNFRII between asthma and COPD [mean fold difference (95% CI): IL-8, 2.6 (1.3–5.4), p = 0.01; TNFRI, 2.1 (1.3–5.4), p = 0.03; TNFRII, 2.6 (1.2–5.6), p = 0.02]. In neutrophilic and eosinophilic airway inflammation, TNFα, TNFRI, TNFRII, IL-6, IL-8 and IL-5 could differentiate between these phenotypes. However, these phenotypes were unrelated to the diagnosis of asthma or COPD. Conclusion: Recovery of sputum mediators sensitive to DTT can be improved using the described sputum processing technique. Within airway inflammatory sub-phenotypes there is a differential pattern of mediator expression that is independent of disease. Whether these inflammatory phenotypes in asthma and COPD confer distinct pathogeneses, therapeutic responses and clinical phenotypes needs to be further evaluated.

Systemic upregulation of neutrophil -defensins and serine proteases in neutrophilic asthma

The well-characterised airway inflammatory phenotypes of asthma include eosinophilic, neutrophilic, mixed eosinophilic/neutrophilic and paucigranulocytic asthma, identified based on the proportion of sputum granulocytes. Systemic inflammation is now recognised as an important part of some airway diseases, but the involvement of systemic inflammation in the pathogenesis of airway inflammatory phenotypes of asthma remains unknown. Induced sputum samples and peripheral blood were collected from participants with asthma (n=36). Airway inflammatory cell counts were performed from induced sputum and inflammatory phenotype assigned based on the airway eosinophil and neutrophil cut-offs of 3% and 61%, respectively. RNA was extracted from whole blood and gene expression profiles were generated (Illumina Humanref-8 V3) and analysed using GeneSpring GX11. There were six genes classified as differentially expressed between the four asthma phenotypes, including the α-defensins (DEFA) 1, 1B, 3 and 4 and neutrophil proteases cathepsin G (CTSG) and elastase (ELA2). Systemic expression of DEFA1,1B,3,4,CTSG and ELA2 was significantly higher in the neutrophilic asthma (NA) phenotype. Microarray results of the α-defensins and neutrophil proteases were successfully validated using real-time PCR. Plasma elastase was significantly increased in people with neutrophilic airway inflammation. There is systemic upregulation of α-defensin and neutrophil protease expression in NA, which may represent proinflammatory effects on the bone marrow and the release of immature neutrophils into the circulation. This demonstrates a systemic inflammatory component in NA that further differentiates this from other asthma phenotypes and indicates different mechanisms in NA.

Transcriptional phenotypes of asthma defined by gene expression profiling of induced sputum samples

Previous studies have identified clinical or inflammatory phenotypes of asthma on the basis of clinical and demographic parameters or sputum cell counts; however, few studies have defined transcriptional phenotypes of asthma. To investigate asthma phenotypes at a transcriptional level by using gene expression profiling of induced sputum. Induced sputum samples were collected from 59 people with asthma with a mean age of 58 years and an FEV(1)% predicted of 76%, and 69% were taking inhaled corticosteroids. Thirteen healthy controls without asthma were also assessed. Inflammatory cell counts were performed, and RNA was extracted from selected sputum. Transcriptional profiles were generated (Illumina Humanref-8 V2) and analyzed by using GeneSpring GX11. Unsupervised hierarchical clustering of gene expression profiles in asthma revealed 3 distinct groups. The first transcriptional phenotype (n = 21) had lower FEV(1)% predicted and higher asthma control questionnaire scores, exhaled nitric oxide, and sputum eosinophils. The second transcriptional phenotype (n = 14) had lower FEV(1)% predicted and forced vital capacity % predicted and higher sputum neutrophils compared with a third transcriptional phenotype (n = 24) that had higher sputum macrophages and resembled healthy controls. Differentially expressed genes between transcriptional asthma phenotypes were related to inflammatory and immune responses. Genes in the IL-1 and TNF-α/nuclear factor-κB pathways were overexpressed and correlated with clinical parameters and neutrophilic airway inflammation. Gene expression profiling provides a novel means to investigate the molecular mechanisms and classifications of asthma phenotypes. There are 3 distinct transcriptional phenotypes of asthma that relate to both clinical and inflammatory parameters.

Airway inflammation in asthma: current and future targets and therapies

Educational aims To provide an overview of airway inflammation in asthma. To review current management guidelines9 recommendations for the use of anti-inflammatory therapies in asthma. To discuss current treatment options for airway inflammation in asthma. To outline unmet needs for treating airway inflammation in asthma. To describe novel targets for treating airway inflammation in asthma based on current knowledge. Summary Asthma is a chronic inflammatory disease of the airways that requires long-term anti-inflammatory therapy. Inhaled corticosteroids (ICS) are recommended for first-line treatment of persistent disease, but not all patients achieve asthma control even when these agents are used in high doses and in combination with other medications, such as a long-acting β2-agonist (LABA) or a leukotriene modifier. Such patients may require additional therapy. As information about asthma pathophysiology and inflammatory phenotypes continues to accumulate, and additional anti-inflammatory options become available, it may be possible to target anti-inflammatory therapy to various aspects of the disease and consequently to improve treatment of patients who respond inadequately to standard ICS-based therapy. Several novel anti-inflammatory therapies are at different stages of clinical development. This article will provide an overview of current and future approaches targeting airway inflammation in asthma.

Inflammatory phenotypes in adult asthma: clinical applications

The pattern of granulocyte infiltration can be used to identify different inflammatory phenotypes in asthma. Recognized granulocyte phenotypes using induced sputum are eosinophilic (EA), neutrophilic, mixed granulocytic and paucigranulocytic asthma. The recognition and importance of inflammatory phenotype analysis using induced sputum in adult asthma are reviewed using published literature. Knowledge of inflammatory phenotype is useful because it relates to treatment response, mechanistic pathways involved in disease pathogenesis and future disease risk. The population attributable risk of asthma because of eosinophilic inflammation is about 50%, and conversely, this means that up to 50% of asthma cannot be attributed to eosinophilic inflammation, and represents asthma associated with non-eosinophilic processes. In these patients, bronchial biopsy shows significantly fewer eosinophils in the bronchial mucosa than subjects with EA. This confirms that non-eosinophilic asthma is a consistent pattern/phenotype in the airway lumen and the airway mucosa. A key aspect of asthma inflammatory phenotype analysis is that it can be applied to individual patients. The underlying principle relates to the association between a clinical response to corticosteroids and the presence of a selective sputum eosinophilia. Clinically useful applications of induced sputum analysis are the detection of non-adherence to corticosteroid therapy, assessment of adequacy of inhaled corticosteroid therapy, long-term therapy management in asthma, oral corticosteroid dose adjustment in refractory asthma and assessment of occupational asthma.

Targeting Airway Inflammation in Asthma: Current and Future Therapies

Asthma is a chronic inflammatory disease of the airway that requires long-term antiinflammatory therapy. Inhaled corticosteroids (ICSs) are recommended for first-line treatment of persistent disease, but not all patients achieve asthma control even when these agents are used in high doses and in combination with other medications, including a long-acting beta(2)-agonist or a leukotriene modifier. Such patients may require additional therapy. As information about asthma pathophysiology and inflammatory phenotypes continues to increase, and additional antiinflammatory options become available, it may be possible to target antiinflammatory therapy to various aspects of the disease and consequently to improve the treatment of patients with inadequate responses to standard ICS-based therapy. Several novel antiinflammatory therapies are in different stages of clinical development. The most clinically advanced of these is omalizumab, a recombinant humanized monoclonal antibody that specifically targets IgE and is indicated for patients with moderate-to-severe asthma caused by allergies. Omalizumab has demonstrated efficacy in patients with moderate-to-severe asthma and documented evidence of allergen sensitivity. Other key therapy options in clinical development either target proinflammatory cytokines (eg, interleukin-4 and tumor necrosis factor-alpha) or inflammatory cells (eg, T-helper type 2 cells and eosinophils). This review provides an overview of the current and future approaches targeting airway inflammation in patients with asthma.

Differential Proteolytic Enzyme Activity in Eosinophilic and Neutrophilic Asthma

Asthma is characterized by both chronic inflammation and remodeling of the airways. Proteases are important mediators of inflammation, cytokine activation, and tissue remodeling. This study investigated matrix metalloproteinase-9 (MMP-9) and neutrophil elastase (NE) enzyme activity in the sputum of subjects with different inflammatory phenotypes of asthma (eosinophilic, neutrophilic, and paucigranulocytic asthma) and in healthy control subjects. Nonsmoking adults with asthma and healthy control subjects underwent hypertonic saline challenge and sputum induction. Selected sputum portions were dispersed with dithiothreitol and assayed for MMP-9 and NE enzyme activity. Subjects with eosinophilic asthma had significantly more active MMP-9 (39 ng/ml) compared with those with neutrophilic asthma (10 ng/ml) and control subjects (2.5 ng/ml, p < 0.01). Although there were high levels of total MMP-9 in neutrophilic asthma (5,273 ng/ml), most (> 99%) was inactivated (and bound to tissue inhibitor of metalloproteinase-1). In neutrophilic asthma, more subjects had NE activity (39%) compared with both healthy control subjects (0%), subjects with eosinophilic asthma (6%), or subjects with paucigranulocytic asthma (0%, p < 0.05). There were strong and consistent positive correlations between interleukin-8, neutrophils, and proteolytic enzymes. MMP-9 was inversely correlated with NE (r = -0.93). Proteolytic enzyme activity in asthma is dependent on the underlying inflammatory phenotype and is differentially regulated with MMP-9 activity a feature of eosinophilic inflammation, and active NE in neutrophilic inflammation.