Human Reconstituted Nasal Epithelium, a promising in vitro model to assess impacts of environmental complex mixtures

•Human reconstituted epithelium tolerates repeated exposures during several weeks•A repeated exposure design close to the realistic human exposure conditions•Human reconstituted epithelium, a relevant model to assess the effect of environmental complex mixture

Considering the impact of respiratory diseases around the world, appropriate experimental tools to help understand the mechanisms involved in such diseases are becoming essential. Our aim was to investigate the cellular and morphological reactivity of a human Reconstituted Nasal Epithelium (hRNE) to evaluate the impact of environmental complex mixture (ECM), with tobacco smoke as a model, after three weeks of repeated exposures.Staining of hRNE showed a multilayered ciliated epithelium, with a regular cilia beats, and a mucus production. When hRNE was exposed to ECM for 5 min once or twice a week, during 3 weeks, significant changes occurred: IL-8 production significantly increased 24 h after the first exposure compared with Air-exposure and only during the first week, without any loss of tissue integrity. Immunostaining of F-actin cytoskeleton showed a modification in cellular morphology (number and diameter).Taken together our results indicate that hRNE is well suited to study the cellular and morphological effects of repeated exposures to an environmental complex mixture. Human reconstituted epithelium models are currently the best in vitro representation of human respiratory tract physiology, and also the most robust for performing repeated exposures to atmospheric pollutants.