Abstract
Introduction: Response to glucocorticosteroid (GCS) therapy in asthma is assessed by reduction in eosinophil counts. Phosphoinositide-3 kinase (PI3K) pathway may contribute to GCS insensitivity in severe asthma.
Aims and objectives: The effect of PI3K antagonism was evaluated on GCS induced eosinophil apoptosis as a mechanism of GCS insensitivity.
Methods: Blood eosinophils, isolated from 7 healthy subjects (HS) and 18 asthmatics, were incubated with increasing concentrations of dexamethasone (0.1, 1 and 10uM) and a pan-PI3K antagonist (LY294002 at 1 and 2uM). Cell viability was assessed using PrestoBlue cell viability assay, Trypan Blue exclusion test and PE-Annexin-V/7-AAD apoptosis detection (flow cytometry).
Results: In HS, a time-dependent increase in eosinophil apoptotic% was observed (1.9% at baseline, 25.7% at 16h and 31% at 24h) (p=0.06, p=0.005 respectively). Dexamethasone 10uM increased it to 40.1% at 16h (p=0.03). Dexamethasone induced eosinophil apoptosis was less in severe asthmatics (34.2%) vs. to mild-to-moderate asthmatics (46.7%) (p=0.05) suggesting steroid insensitivity (Fig. 1A). This was not reversed by co-incubation with LY294002 2uM (39.9% vs. 53.3%) (p=0.04) (Fig. 1B).
Conclusions: Evaluating dexamethasone-induced apoptosis in blood eosinophil can assess GCS sensitivity ex vivo. Severe asthmatics demonstrate GCS insensitivity, which was not reversed by a pan-PI3K antagonist.
Footnotes
Cite this article as Eur Respir J 2022; 60: Suppl. 66, 3660.
This article was presented at the 2022 ERS International Congress, in session “-”.
This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
- Copyright ©the authors 2022
