A primary cell model of the very preterm epithelium reveals barrier defects at 1 year of age.

Background and aims: Limited evidence suggests that airway epithelial structure and function is disrupted in very preterm infants; however, the epithelial morphology and physiology has not been well characterised following discharge from neonatal intensive care. This study aimed to characterise the nasal airway epithelium from 1-year-old survivors of very preterm birth. Methods: Nasal brushings were sampled from infants born either at term or very preterm and differentiated cultures established. Fixed cultures were used for histological analysis and staining for cilia and mucus, with RNA collected for PCR analysis of tight junction proteins and cell type characterisation. Barrier integrity was assessed using transepithelial electrical resistance (TEER) and cell permeability assays. Results: Differentiated cultures were successfully established in 50% of preterm (final n=12, mean±sd 1.4±0.1 years) and 90% of term samples (final n=9, 2.7±0.6 years). Preterm cells had significantly reduced TEER (median (interquartile range (IQR)) 292.4 (160.6) Ω·cm-2 versus 191.6 (114.5) Ω·cm-2; p<0.05) and showed increased cell permeability (median (IQR) 3.25 (5.13) cm·s-1 versus 9.01 (2.30)×10-4 cm·s-1; p<0.01). PCR analysis of tight-junction related genes showed no statistical differences in expression of TJP1 or CLDN1, but protein staining revealed altered tight-junction patterning. Conclusions: The airway epithelial barrier appears compromised in survivors of very preterm birth at 1 year of age. Reduced epithelial barrier strength creates vulnerability to infection and injury, which can negatively impact overall lung health across the lifespan.