Inflammatory and antioxidant effects of inhaled nanoparticles on human primary bronchial epithelial cells

Air pollution is a major risk factor for various respiratory diseases, in particular for disease progression in COPD. Therefore, it is very important to understand pathophysiological mechanisms that determine specific interactions between air pollutants and the bronchial epithelium, thereby informing future diagnostic and treatment regimen. Primary human bronchial epithelial cells (pHBECS) from healthy/ diseased lung tissue were exposed on air-liquid interface (ALI) with relevant aerosolized nanoparticles (NPs; Carbon black nanoparticles /CNP, Zinc oxide /ZnO) and LPS, using the ALICE-CLOUD system. The functional cell viability, inflammatory and anti-oxidant response were analyzed by TEER, WST-1, LDH, qPCR and ELISA. For further validation, a novel ex-vivo airway model was established by culturing native bronchial mucosa on ALI and analyzed by 3D confocal immunofluorescence. ZnO NPs (31,8µg/cm2) induced epithelial barrier impairment after 4h (81%) and reduced viability (37% after 4h and 23% after 24h). Only ZnO NPs revealed an antioxidant response with 100-fold increased HMOX-RNA expression after 24h. qPCR analysis suggested increased TNF (3-fold) and IL8-RNA (2-fold) expression, 24h after ZnO (31,8µg/cm2) exposure. The ELISA analysis suggested an 1,5-fold increased IL8 concentration 4h after ZnO (9,3ng/ml) or LPS (10,8ng/ml) exposure. ZnO but not CNP cause epithelial barrier and cell viability impairment with the involvement of inflammatory and antioxidant pathways. The novel ex-vivo culture model based on bronchial tissue might be an important tool to validate the differentiation of the pHBECs and to better understand the inflammatory processes at the level of main bronchi.