Hyperglycemia differentially affects neutrophil transmigration across cystic fibrosis and wildtype bronchial...

Hallmarks of Cystic Fibrosis (CF) lung disease are chronic obstruction, infection, and inflammation dominated by lifelong, excessive influx of neutrophils (PMNs) into airways which is further exacerbated by CF-related diabetes (CFRD).

We examined the effect of glycemic state (normal glucose, NG and high glucose, HG) on PMN mucosal-to-luminal transmigration across bronchial epithelia using 16HBE (16HBE-WT, 16HBE-CF) or primary airway epithelial cells expressing either WT- or F508del-CFTR (NhBE and CFhBE) cultured on Transwell filters, and whether rates of transmigration are sensitive to highly effective modulator therapies (HEMTs) used for CF.

We observed a time-dependent decrease in transepithelial resistance (TER), during transmigration of healthy PMNs across 16HBE monolayers. TER after transmigration was significantly lower for cells cultured in HG compared to NG. Transmigration rate across 16HBE-WT monolayers was higher when cultured in HG while the rate was higher across 16HBE-CF monolayers cultured in NG. Transmigration rate across NhBE monolayers was higher for cells cultured in HG compared to NG. No differences in rates of transmigration across CF primary monolayers were detected in NG versus HG. Differences in transmigration rates were partly normalized by exposure to HEMTs. Unlike naïve PMNs and PMNs that transmigrated across empty wells, PMNs that crossed 16HBE and primary cell monolayers were enlarged, had a rough plasma membrane morphology, and an abundance of large vacuoles.

These data show that HG conditioning impacts PMN transmigration, and that transmigrated PMNs are differentially impacted by the CFTR genotype of the cell monolayer through which they have transmigrated.