Single-cell transcriptomics reveals subset-specific metabolic profiles underpinning the bronchial epithelial response to flagellin

Airway epithelial cells represent the first line of defense against respiratory pathogens. Flagellin drives the motility of many mucosal pathogens and has been suggested as an immune enhancing adjunctive therapeutic in infections of the airways. This study leveraged single-cell RNA sequencing to determine cell-specific effects of flagellin in primary human bronchial epithelial cells growing in air-liquid interface. Seven cell clusters were identified, including ciliated cells, ionocytes and several states of basal and secretory cells, of which only inflammatory basal cells and inflammatory secretory cells demonstrated a proportional increase in response to flagellin. Inflammatory secretory cells showed evidence of metabolic reprogramming toward aerobic glycolysis, whilst in inflammatory basal cells transcriptome profiles indicated enhanced oxidative phosphorylation. Inhibition of mTOR prevented the shift to glycolysis and reduced inflammatory gene transcription specifically in inflammatory secretory cells. This data demonstrates the functional heterogeneity of the human airway epithelium upon exposure to flagellin. Overall design: HBE cells were derived from healthy tracheobronchial tissue obtained from a lobectomy in a patient with lung cancer at the Amsterdam University Medical Centers in the Netherlands, as previously reported. The Institutional Review Board of Amsterdam UMC approved the study protocol (2015-122#A2301550) and written informed consent was obtained from the donor before sampling.