Alarmin release in the bronchial epithelium of allergic asthma patients vary in response to different aeroallergens

Abstract

<b>Background:</b> Allergic asthma is a chronic inflammatory disease and airway epithelial cells release danger-associated molecular patterns (DAMPs) and alarmins in response to different allergens. It remains unclear how different allergens trigger pro-inflammatory pathways. <b>Aim:</b> To investigate the alarmin response and DAMPs release to four different aeroallergens in human bronchial epithelial cells (HBECs) from patients with allergic asthma. <b>Methods:</b> Primary HBECs from 20 allergic asthmatic donors were cultured in vitro and exposed to Alternaria alternata (200µg/mL), Artemisia Vulgaris (1000µg/mL), Betula pendula (200µg/mL) and House dust mite (HDM; 20µg/mL), for 1, 3 and 24h. TSLP and IL33 gene expression was analysed by RT-qPCR, whereas protein levels were measured by ELISA. ATP and UA release was measured by biochemical assay. <b>Results:</b> B. pendula significantly induced ATP release after 1h. All allergens studied induced IL33 and TSLP mRNAs, but only HDM induced a significant release of IL33 and TSLP proteins. Moreover, TSLP release after HDM exposure was sustained at 24h and only HDM induced UA release in HBECs at 24h. <b>Conclusion:</b> Aeroallergens had differential effect on HBECs alarmin response. All allergens induced early gene expression of TSLP and IL33, but HDM stood out by also causing release of IL-33 and TSLP at 3h exposure, and TLSP and UA at 24h. These data suggest HDM as major pathogenic trigger of allergic asthma.