Modulating the Barrier Function of Human Alveolar Epithelial (hAELVi) Cell Monolayers as a Model of Inflammation

The incidence of inflammatory lung diseases such as acute respiratory distress syndrome (ARDS) remains an important problem, particularly in the present time with the Covid-19 pandemic. However, an adequate in vitro test system to monitor the barrier function of the alveolar epithelium during inflammation and for assessing anti-inflammatory drugs is urgently needed. Therefore, we treated human Alveolar Epithelial Lentivirus-immortalised cells (hAELVi cells) with the pro-inflammatory cytokines TNF-alpha (25 ng/ml) and IFN-gamma (30 ng/ml), in the presence or absence of hydrocortisone (HC). While TNF-alpha and IFN-gamma are known to reduce epithelial barrier properties, HC could be expected to protect the barrier function and result in an anti-inflammatory effect. We investigated the impact of anti-inflammatory/inflammatory treatment on transepithelial electrical resistance (TEER) and the apparent permeability coefficient (P-app) of the low permeability marker sodium fluorescein (NaFlu). After incubating hAELVi cells for 48 hours with a combination of TNF-alpha and IFN-gamma, there was a significant decrease in TEER and a significant increase in the P-app. The presence of HC maintained the TEER values and barrier properties, so that no significant P-app change was observed. By using hAELVi cells to study anti-inflammatory drugs in vitro, the need for animal experiments could be reduced and pulmonary drug development accelerated.