Influenza Infects Lung Microvascular Endothelium Leading to Microvascular Leak: Role of Apoptosis and Claudin-5
Figure 3
Human influenza induces lung endothelial apoptosis.
(A) Influenza induces loss of endothelial cell viability, detected by phase contrast microscopy. Cells were infected for 24 hours at the indicated multiplicity of infection (MOI). Images were captured using a Nikon Eclipse and are representative of 3 experiments. (B) Influenza induces lung endothelial apoptosis as shown by flow cytometry. Cells were infected with influenza at the indicated MOI for 4 hours and binding of annexin V was measured. (C) The number of annexin V-positive cells increased significantly in a dose-dependent fashion. Y-axis is the percentage of cells that are positive for annexin V. Results (mean, SE) are from 4 experiments, *p<0.05. (D) ZVAD-FMK partially prevents the induction of influenza-mediated lung endothelial permeability. Endothelial cells on transwells were infected with influenza (80 HAU/100 000 cells) for 24 hours with or without 80 µM ZVAD-FMK. Permeability to dextran was measured. Results (mean, SE) are from 4 experiments and are normalized to control, *p<0.05.