Human Bronchial Epithelial Cell-Derived Factors from Severe Asthmatics Can Stimulate Local Eosinophilopoetic Responses (original) (raw)

Rationale: Activated bronchial epithelial cells release alarmins, including thymic stromal lymphopoietin (TSLP) that drive type 2 inflammations. We hypothesize that bronchial epithelial cell-derived factors promote in situ eosinophil differentiation and maturation , a process that is driven by an IL-5 rich micro-environment in asthmatic airways. Methods: To assess the eosinophilopoietic potential of epithelial-derived factors, eosinophil/basophil colony forming units (Eo/B-CFU) were enumerated in 14-day methylcellulose cultures of blood-derived mononuclear cells (NAMNCs) incubated with bronchial epithelial cell supernatants (BECSN) from healthy non-atopic controls (NC; n = 8), mild atopic asthmatics (MA; n = 9) and severe asthmatics (SA; n = 5). Receptor blocking antibodies were used to evaluate the contribution of alarmins. Modulation of mRNA expression of transcription factors crucial for eosinophil differentiation was evaluated. Results: BECSN stimulated the clonogenic expansion of eosinophil progenitors, in vitro. In the presence of IL-5, Eo/B-CFU numbers were significantly greater in co-cultures of BESCN from SA, compared to other groups. This was attenuated in the presence of a TSLP receptor-but not IL-33 receptor-blocking antibody. Recombinant human TSLP (optimal at 100 pg/ml) stimulated Eo/B-CFU growth, which was significantly enhanced in presence of IL-5 (1 ng/ml). Overnight culture of CD34 + cells with IL-5 and TSLP synergistically increased GATA-2 and CEBP-alpha mRNA expression.