Abstract
RATIONALE: The structural integrity of the alveolar epithelial monolayer depends on the balance between inward tension forces and outward adhesive tethering forces at cell-cell contacts. During the early stages of acute lung injury, this balance might be affected by alterations in the coagulation cascade. We aimed to study the effects of activated protein C (APC) on barrier integrity in cultured human lung epithelial cells exposed to thrombin (Thr). METHODS: The dynamics of barrier function were evaluated by measurements of transepithelial impedance (TI). Cell lines A549 and H441 and primary culture of human alveolar epithelial cells (HAECs) grown to confluence on gold microelectrodes, were pretreated with APC (50μg/ml) or culture medium (vehicle) for 3h. Subsequently, 50nM Thr or medium was added to the cell culture. TI was measured every minute up to 70 minutes. Cells pretreated with vehicle for 3h and challenged with medium instead of Thr were defined as control group. RESULTS: The acute response to Thr produced a significant decline in TI in all three cell types: 12.6% in A549, 13.5% in HAECs, and 5.8% in H441, reflecting increased permeability. This decline in TI was rapid, reaching a low point between 1 and 10 min after Thr challenge. Then, the pattern of the response to Thr in the three human lung epithelial cell types differed. The Thr-induced acute decline in TI was significantly attenuated by pretreatment with APC in all three cell types (4.6% in A549, 5.9% in HAECs, and 1.4% in H441 cells), suggesting a barrier-protective response. No significant changes in TI values were found between with APC pretreated cells and control cells. ACKNOWLEDGEMENT: FIS-PI08/0646 and Fundació Parc Taulí.
- © 2013 ERS
