Effect of mechanical stretch on permeability of human pulmonary vascular endothelial cells and underlying molecular mechanism

Abstract

Objective To observe the effect of mechanical stretch on the permeability of human pulmonary artery endothelial cells (HPAECs) and human pulmonary microvascular endothelial cells (HPMVECs) and to examine whether the expression of the key permeability-related proteins VE-cadherin, Claudin-5, and Caveolin-1 is involved in this process. Methods The mechanical stretch device Flexcell FX-5000T was used to apply 10% or 20% tensile stress to HPAECs and HPMVECs at a frequency of 0.5 Hz. qRT-PCR and Western blot were used to detect the mRNA and protein expression of VE-cadherin, Claudin-5, and Caveolin-1 in cells before and after mechanical stretch. Mechanical stretched HPAEC cells and HPMVEC cells were monitored by a cell dynamic analyzer and Transwell chamber/FITC-albumin assay to detect their permeability. Results In HPAECs after mechanical stretch, the expression of VE-cadherin mRNA and protein, Claudin-5 mRNA and protein, and Caveolin-1 mRNA decreased significantly compared with control cells (P<0.05), while the level of Caveolin-1 protein did not change significantly compared with the control group. In HPMVECs after mechanical stretch, the expression of VE-cadherin mRNA and protein and Caveolin-1 mRNA and protein decreased significantly compared with control cells (P<0.05), while the levels of Claudin-5 mRNA and protein did not change significantly compared with the control group. Conclusion Mechanical stretch leads to increased permeability of pulmonary vascular endothelial cells, which is caused by down-regulation of the expression of permeability key proteins, but the permeability mechanisms of the two cell types are different: HPAECs involve tight junctions and HPMVECs involve the transendothelial pathway. Key words: Mechanical stretch; Human pulmonary artery endothelial cells; Human pulmonary microvascular endothelial cells; VE-cadherin; Claudin-5; Caveolin-1