Pathways linked to unresolved inflammation and airway remodelling characterize the transcriptome in two independent severe asthma cohorts.

BACKGROUND AND OBJECTIVE: Severe asthma (SA) is a heterogeneous disease. Transcriptomic analysis contributes to the understanding of pathogenesis necessary for developing new therapies. We sought to identify and validate mechanistic pathways of SA across two independent cohorts. METHODS: Transcriptomic profiles from U-BIOPRED and Australian NOVocastrian Asthma cohorts were examined and grouped into SA, mild/moderate asthma (MMA) and healthy controls (HCs). Differentially expressed genes (DEGs), canonical pathways and gene sets were identified as central to SA mechanisms if they were significant across both cohorts in either endobronchial biopsies or induced sputum. RESULTS: Thirty-six DEGs and four pathways were shared across cohorts linking to tissue remodelling/repair in biopsies of SA patients, including SUMOylation, NRF2 pathway and oxidative stress pathways. MMA presented a similar profile to HCs. Induced sputum demonstrated IL18R1 as a shared DEG in SA compared with healthy subjects. We identified enrichment of gene sets related to corticosteroid treatment; immune-related mechanisms; activation of CD4+ T cells, mast cells and IL18R1; and airway remodelling in SA. CONCLUSION: Our results identified differentially expressed pathways that highlight the role of CD4+ T cells, mast cells and pathways linked to ongoing airway remodelling, such as IL18R1, SUMOylation and NRF2 pathways, as likely active mechanisms in the pathogenesis of SA.

Innate immune responses are increased in chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterised by irreversible airflow obstruction, neutrophilic airway inflammation and chronic bacterial colonisation, however the role of the innate immune response in the pathogenesis of COPD remains unclear. METHODS: Induced sputum was obtained from adults with COPD (n=22), and healthy controls (n=29) and was processed for differential cell counts. The sputum supernatant was assayed for innate immune mediators using ELISA, whilst sputum gene expression was measured using real-time PCR. Peripheral blood neutrophils were isolated and their response to lipopolysaccaride (LPS) stimulation was assessed in a subgroup of participants with COPD (n=13) and healthy controls (n=21). RESULTS: Participants with COPD had significantly higher protein levels of interleukin (IL)-8, and neutrophil elastase (NE) and detection of oncostatin M (OSM) compared to healthy controls. Gene expression for toll-like receptor (TLR) 2, IL-8 and OSM were also significantly higher in COPD participants. The level of IL-1ß, surfactant protein (SP)-A, matrix metalloproteinase (MMP)-9 and TLR4 mRNA was not significantly different between groups. The level of innate immune response markers were highly associated with the presence of sputum neutrophils, each other and the degree of airflow limitation (FEV1/FVC). Peripheral blood neutrophils from participants with COPD had an increased response to stimulation by LPS; with a greater fold increase in the production of IL-8 and MMP-9 protein, and gene expression of IL-8, TLR2 and TLR4. CONCLUSIONS: The innate immune response is increased in the airways and circulating neutrophils in COPD, and may be an important mechanism involved in disease pathogenesis.

Anti-inflammatory effect of itraconazole in stable allergic bronchopulmonary aspergillosis: a randomized controlled trial.

BACKGROUND: Allergic bronchopulmonary aspergillosis (ABPA) complicates chronic asthma and results from hypersensitivity to the fungus Aspergillus fumigatu s, causing an intense systemic immune response and progressive lung damage. OBJECTIVE: We sought to determine whether treatment with the antifungal agent itraconazole reduced eosinophilic airway inflammation in subjects with ABPA. METHODS: A randomized, double-blind, placebo-controlled trial was performed in stable subjects with ABPA (n = 29). Subjects received 400 mg of itraconazole per day (n = 15) or placebo (n = 14) for 16 weeks. All subjects were reviewed monthly with history, spirometry, and sputum induction to measure airway inflammation, serum total IgE and IgG levels to A fumigatu s, and blood eosinophil counts. RESULTS: By using regression analysis in a random-effects model, subjects receiving itraconazole had a decrease in sputum eosinophils of 35% per week, with no decrease seen in the placebo arm (P <.01). Sputum eosinophil cationic protein levels decreased with itraconazole treatment by 42% per week compared with 23% in the placebo group (P <.01). Itraconazole reduced systemic immune activation, leading to a decrease in serum IgE levels (310 IU/mL) compared with levels seen in the placebo group (increase of 18 IU/mL, P <.01) and a decrease in IgG levels to A fumigatu s (15.4 IU/mL) compared with levels seen in the placebo group (increase of 3.7 IU/mL, P =.03). There were fewer exacerbations requiring oral cortico-steroids in those treated with itraconazole compared with in the placebo group (P =.03). CONCLUSION: Itraconazole treatment of subjects with stable ABPA reduces eosinophilic airway inflammation, systemic immune activation, and exacerbations. These results imply that itraconazole is a potential adjunctive treatment for ABPA.