Neuroendocrine cells initiate protective upper airway reflexes

Airway neuroendocrine (NE) cells have been proposed to serve as specialized sensory epithelial cells that modulate respiratory behavior by communicating with nearby nerve endings. However, their functional properties and physiological roles in the healthy lung, trachea and larynx remain largely unknown. Here, we show that NE cells in these compartments possess distinct biophysical properties, but share sensitivity to the commonly aspirated noxious stimuli, water and acid. Moreover, we found that tracheal and laryngeal NE cells protect the airways by releasing ATP to activate purinoreceptive sensory neurons that initiate swallowing and expiratory reflexes. Our work uncovers striking molecular and biophysical diversity of NE cells across the airways and reveals mechanisms by which these specialized excitable cells serve as sentinels for activating a critical nociceptive circuit. Compare expression between neuroenodcrine cells and epithelial cells in the lung, lower trachea, upper trachea, larynx. Cells were dissociated and FACs sorted from Ascl1-CreERT2;lsl-tdTomato mice with neuroendocrines cells defined as tdTomato+ and epithelial cells defined as EpCam+/tdTomato-. For a given tissue, NE and epithelial cells were FACs sorted in parallel (n=3 biological replicates). Lung cells were dissociated from one set of mice and tracheal/laryngeal NE cells were dissociated from another set.