Abstract Rationale Pulmonary ionocytes, marked by the expression of the key transcription factor FOXI1, have been identified as a rare cell type of both mouse and human airways that express more than 90% of CFTR transcripts. Currently the functional relevance of pulmonary ionocytes in modulating airway ion and fluid transport in normal and diseased airways remains unknown. Emerging work has shown altered expression of ionocytes in patients with type 1 and type 2 asthma as well type 2 cytokine (IL-4, IL-13) mediated perturbation ionocytes in in vitro culture. We have developed an iPSC derived airway epithelial culture model which recapitulates airway epithelium including pulmonary ionocytes and models genotype specific effects in asthma. Methods iPSCs were derived from healthy controls. Asthmatics were classified as low/medium/high/risk based altered single nucleotide polymorphisms (SNP) in the 17q12 region at rs12936231 based on prior work. iPSCs underwent directed differentiation to airway epithelium and were cultured for a minimum of 21 days at air liquid interface. Transwells underwent challenge the dsRNA viral mimetic Poly(I:C) or IL-13. Transwell cultures were harvested for RNA and subsequent transcriptional analysis as well as immunostaining. Ionocyte proportions in the given cultures were characterized via IFA. Ionocyte numbers in iPSC airway culture were modified through the use of coculturing studies introducing a population of iPSC-basal cells with inducible FOXI1 to trigger ionocyte specification Results iPSC derived airway epithelium from asthmatics and healthy controls exhibited no baseline significant differences in the cell type canonical markers TP63, MUC5B, MUC5AC, SCGB1A1, FOXJ1. In response to IL-13 challenge asthmatic lines showed increased secretory cell proliferation by transcript and immunostaining. Ionocyte markers decreased in response to IL-13 challenge. Artificial increase in ionocyte numbers via inducible FOXI1 resulted in a reduction in secretory cell numbers. Conclusions Our preliminary studies indicate that iPSC derived respiratory epithelium can be used to successfully model ionocytes in an in vitro asthma model system. Our findings of reduced ionocyte markers with IL-13 challenge agree with primary culture studies suggesting a link between type 2 cytokine exposure and ionocyte composition within the respiratory epithelium. Restoration of ionocytes showed reduction in secretory cell population, suggesting that ionocytes may represent a novel therapeutic target This abstract is funded by: NHBLI
Rollins et al. (Fri,) studied this question.
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