TY - JOUR TI - Autofluorescence imaging permits label-free cell type assignment and reveals the dynamic formation of airway secretory cell associated antigen passages (SAPs) AU - Shah, Viral S AU - Hou, Jue AU - Vinarsky, Vladimir AU - Xu, Jiajie AU - Surve, Manalee V AU - Lin, Charles P AU - Rajagopal, Jayaraj A2 - Noble, Paul W VL - 12 PY - 2023 DA - 2023/03/30 SP - e84375 C1 - eLife 2023;12:e84375 DO - 10.7554/eLife.84375 UR - https://doi.org/10.7554/eLife.84375 AB - The specific functional properties of a tissue are distributed amongst its component cell types. The various cells act coherently, as an ensemble, in order to execute a physiologic response. Modern approaches for identifying and dissecting novel physiologic mechanisms would benefit from an ability to identify specific cell types in live tissues that could then be imaged in real time. Current techniques require the use of fluorescent genetic reporters that are not only cumbersome, but which only allow the study of three or four cell types at a time. We report a non-invasive imaging modality that capitalizes on the endogenous autofluorescence signatures of the metabolic cofactors NAD(P)H and FAD. By marrying morphological characteristics with autofluorescence signatures, all seven of the airway epithelial cell types can be distinguished simultaneously in mouse tracheal explants in real time. Furthermore, we find that this methodology for direct cell type-specific identification avoids pitfalls associated with the use of ostensibly cell type-specific markers that are, in fact, altered by clinically relevant physiologic stimuli. Finally, we utilize this methodology to interrogate real-time physiology and identify dynamic secretory cell associated antigen passages (SAPs) that form in response to cholinergic stimulus. The identical process has been well documented in the intestine where the dynamic formation of SAPs and goblet cell associated antigen passages (GAPs) enable luminal antigen sampling. Airway secretory cells with SAPs are frequently juxtaposed to antigen presenting cells, suggesting that airway SAPs, like their intestinal counterparts, not only sample antigen but convey their cargo for immune cell processing. KW - autofluorescence KW - airway epithelia KW - secretory cell associated antigen passages KW - NADH KW - FAD KW - goblet cell associated antigen passages JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -