Development of an acute lung injury model for drug testing.

A challenge that limits our understanding of the underlying pathobiology of pediatric acute respiratory distress syndrome (PARDS) is the lack of a preclinical airway model that can be leveraged for the study of mechanisms and specific molecules for drug testing. We developed a physiologic model system of the small airways for mechanistic application in PARDS using a co-culture of primary human-derived small airway epithelial cells (SAECs) cultured at the air-liquid interface and umbilical vein endothelial cells in a transwell system. The model was validated by exposing the SAECs to a rhinovirus infection, to an inflammatory lung insult using a mixture of cytokines found in ARDS (cytomix), and to airway fluid samples from children with different severity strata of PARDS. We used a combination of transepithelial electrical resistance, immunofluorescence confocal microscopy of tight junctions, targeted gene expression, and cytokine responses to evaluate the model to the aforementioned insults. We then use the model in drug testing and show the reduction in IL-6 expression in conditioned media and STAT3 phosphorylation following co-treatment of SAECs with cytomix and the Janus kinase inhibitor (JAKi) baricitinib. This model enables mechanistic studies of airway pathobiology and may serve as a novel drug testing platform for PARDS.