A One Health Approach to Simple Liquid Sample Handling for Respiratory Based -Omics Analysis; Tracheal Wash and Bronchoalveolar Lavage Fluid

Abstract Airway inflammation is highly prevalent in horses, with the majority of non-infectious cases being defined as equine asthma. Currently, cytological analysis of airway derived samples is the principal method of assessing lower airway inflammation. Samples can be obtained by tracheal wash (TW) or by lavage of the lower respiratory tract (bronchoalveolar lavage fluid; BALF). Although BALF cytology carries significant diagnostic advantages over TW cytology, sample acquisition is invasive, making it prohibitive for routine and sequential-screening of airway health. The aim of this study was to establish a robust protocol to isolate macrophages, protein and RNA for molecular characterisation of TW samples and demonstrate the applicability of sample handling to rodent and human pediatric bronchoalveolar lavage fluid isolates. TW samples provided a good quality and yield of both RNA and protein for downstream transcriptomic/proteomic analyses. The sample handling methodologies were successfully applicable to BALF for rodent and human research. TW samples represent a rich source of airway cells, and molecular analysis to facilitate and study airway inflammation, based on both transcriptomic and proteomic analysis. This study provides a necessary methodological platform for future transcriptomic and/or proteomic studies on equine lower respiratory tract secretions and BALF samples from humans and mice.