Abstract Rationale Severe asthma is a chronic inflammatory disease with elevated numbers of eosinophils in blood, sputum and epithelial dysfunction. In SEA IL-5 is a key cytokine for eosinophil maturation, release and activation, driving disease. Anti-IL5 and anti-IL5Rα biologics mepolizumab and benralizumab are used to treat SEA, causing a reduction in circulating blood eosinophil counts. However, these biologics show variable efficacy in SEA, with unclear response mechanisms. Aims We aim to determine 1) treatment response to anti-IL5/-IL5Rα therapies in nasal epithelial cell (NEC) transcripts and 2) the effect of anti-IL5/-IL5Rα on NEC structure and immune cell presence after 12-months of therapy. Methods NEC were obtained from SEA patients at pre- and 12-months of benralizumab (n = 6) or mepolizumab (n = 6) treatment. Basal NEC cultures were used to determine i) the ability of cells to form a confluent monolayer and attachment (shedding phenotypes of NECs), ii) presence of immune cells in the nasal epithelium and iii) for RNASeq analysis. Response was treatment was determined at 12-months; Complete responders (CR; n = 4) experienced no exacerbations, took ≤5 mg/day prednisolone, Asthma Control Questionnaire-6 score 1.5, and ≥10% improvement in FEV1. Partial response (PR; n = 4) failed one or more of these criteria. Data was aligned using Subread package and differentially expressed genes (DEGs) were identified using DESEQ2 package. DEGs were selected using log2fold-change 2 and adjusted p-value 0.05. Pathway analysis of DEGs was performed using Enrichr software and KEGG. Results The NECs (n = 12) from SEA, on benralizumab or mepolizumab therapy with the removal of circulating eosinophils, show reduced basal shedding, increased barrier integrity (1.5-fold, p = 0.04) and a reduction in nasal eosinophils (p = 0.01). Comparison of CR and PR baseline NEC transcripts identified 71 genes as increased in PRs and 79 genes as increased in CRs. Pathways associated with CR increased genes highlighted upregulated extracellular matrix (ECM)-associated processes including ECM organisation and receptor interactions (p 0.04), Focal adhesion (p 0.006), and Integrin mediated cell adhesion (p 0.007). In PRs, pathways and genes associated with IL-17 signalling (p 0.04), IL-1 signalling (p 0.01), IL-36 signalling (p 0.02), and TNF signalling (p 0.05) were increased. Conclusion Differences in baseline NEC transcripts highlights distinct pathways associated with response to anti-IL5/-IL5Rα biologic therapy. In partial responders, neutrophilic signalling suggests potential insights for precision therapies in SEAs. This abstract is funded by: Medical Research Council (UK):MR/T010371/1 and Imperial College Trust
Raby et al. (Fri,) studied this question.