COL4A3 is degraded in allergic asthma and degradation predicts response to anti-IgE therapy.

BACKGROUND: Asthma is a heterogeneous syndrome substantiating the urgent requirement for endotype-specific biomarkers. Dysbalance of fibrosis and fibrolysis in asthmatic lung tissue leads to reduced levels of the inflammation-protective collagen 4 (COL4A3). OBJECTIVE: To delineate the degradation of COL4A3 in allergic airway inflammation and evaluate the resultant product as a biomarker for anti-IgE therapy response. METHODS: The serological COL4A3 degradation marker C4Ma3 (Nordic Bioscience, Denmark) and serum cytokines were measured in the ALLIANCE cohort (paediatric cases/controls: n=134/n=35; adult cases/controls: n=149/n=31). Exacerbation of allergic airway disease in mice was induced by sensitising to ovalbumin (OVA), challenge with OVA aerosol and instillation of poly(cytidylic-inosinic). Fulacimstat (chymase inhibitor; Bayer) was used to determine the role of mast cell chymase in COL4A3 degradation. Patients with cystic fibrosis (n=14) and cystic fibrosis with allergic bronchopulmonary aspergillosis (ABPA; n=9) as well as patients with severe allergic uncontrolled asthma (n=19) were tested for COL4A3 degradation. Omalizumab (anti-IgE) treatment was assessed using the Asthma Control Test. RESULTS: Serum levels of C4Ma3 were increased in asthma in adults and children alike and linked to a more severe, exacerbating allergic asthma phenotype. In an experimental asthma mouse model, C4Ma3 was dependent on mast cell chymase. Serum C4Ma3 was significantly elevated in cystic fibrosis plus ABPA and at baseline predicted the success of the anti-IgE therapy in allergic, uncontrolled asthmatics (diagnostic OR 31.5). CONCLUSION: C4Ma3 levels depend on lung mast cell chymase and are increased in a severe, exacerbating allergic asthma phenotype. C4Ma3 may serve as a novel biomarker to predict anti-IgE therapy response

A comprehensive way to rate sputum quality in clinical trials

Introduction: The analysis of induced sputum is widely used in clinical trials to assess airway inflammation. Quality of sputum cell samples is variable and currently defined by the level of contamination with squamous cells (SQ%). This definition does not consider the quality of relevant sputum cells. Here we suggest a novel quality score and evaluated how it is related to differential cell count inter-observer variability and agreement. Methods: Thirty sputum cytospin samples, with a broad range of quality, from three DZL sites were analyzed by nine evaluators using standard techniques. Slide quality was rated by all evaluators on a 5-point scale (0, 0.5, 1, 1.5, 2; low-high). The slide quality score included a rating of cell morphology, level of cellular debris and SQ%. Inter-evaluator variability (SD), evaluator accuracy and intra class-correlation coefficients (ICC) between evaluator and overall mean cell counts (as reference) were computed. To assess the relationship between these parameters and slide quality the dataset was split into three quality levels based on the mean slide score (level C: 0.9 and increased for all evaluators, if the slides from the low quality level C were excluded. Conclusion We propose to include sputum leukocyte cell integrity, the amount of cellular debris and SQ% into a slide quality score. Excluding samples based on this score reduced differential cell count inter-evaluator variability and improved the agreement of evaluators with the overall mean differential cell count