Influenza Infects Lung Microvascular Endothelium Leading to Microvascular Leak: Role of Apoptosis and Claudin-5
(A) C57BL/6 mice were infected nasally with UV influenza (128 HAU/mouse and 256 HAU/mouse), and live human influenza (128 HAU/mouse). Some mice infected with live influenza were given formoterol (0.2 mg/kg) or vehicle by intraperitoneal injection immediately afterwards and daily for 3 days. Lung vascular leak was measured by injection of Evans Blue (EB). Results are means normalized to serum EB levels (to control for unequal administration) and to the mean control EB of the experiment, *p<0.05. (B) Replication of influenza (MOI 8) in mouse lung endothelial cells (with or without 0.1 µM formoterol) was assessed by immunofluorescence for viral nucleoprotein as in Figure 1. Data are mean and SE from 3 experiments. (C) The reduction in lung permeability from formoterol is not due to decreased endothelial apoptosis. Mouse endothelial cells infected with live influenza (MOI 8) with or without formoterol (0.1 µM) were probed with Annexin V 24 hours later. Histogram is representative of 3 experiments.