Abstract 1354: Prevention of Endotoxemic Multiple Organ Injury by Overexpressing Degradation-resistant I-κBα Selectively on Endothelium
The critical role of NF-κB activation in septic pathophysiology indicates that NF-κB is a desirable target for treatment of septic shock. NF-κB inhibition impairs bacterial clearance capability, suggesting that NF-κB inhibition is detrimental. Endothelial selective blockade of NF-κB pathway may damp the injurious response without jeopardizing host defense function. To test efficacy of endothelial-selective NF-κB inhibition in preventing endotoxemic organ injury, we created transgenic mice conditionally overexpressing degradation-resistant I-κBα (I-κBαmt) selectively on endothelial cells and studied their response to LPS. Transgenic mice (TG) were induced to express I-κBαmt with doxycyline (2 mg/ml in drinking water) prior to experimentation. Mice in wild type control (WT-con) and TG control (TG-con) groups were injected with saline. Mice in WT-LPS and TG-LPS groups were challenged with E Coli LPS (10 mg/kg, i.p). Compared with WT-con and TG-con, WT-LPS had markedly increased E-selectin, ICAM-1 and VCAM-1 protein expression in multiple organs, which was significantly reduced in TG-LPS mice. Reduced adhesion molecule expression resulted in reduced neutrophil infiltration and endothelial permeability. Tissue myeloperoxidase activity for WT-con, TG-con, WT-LPS and TG-LPS was 0.95±0.15, 0.72±0.14, 3.3±0.24 and 2.2±0.19 for lungs; 0.06±0.02, 0.04±0.02, 0.24±0.02 and 0.15±0.03 for heart; 0.38±0.07, 0.26±0.06, 1.5±0.3 and 0.7±0.11 for liver; 0.22±0.01, 0.16±0.03, 0.54±0.06 and 0.35±0.05 for kidney and 0.38±0.07, 0.41±0.09, 1.5±0.17 and 0.9±0.19 for intestine (p < 0.05 between WT-LPS and TG-LPS groups in all 5 organs). Tissue Evans blue leakage (mg/g tissue) for WT-con, TG-con, WT-LPS and TG-LPS was 0.05±.0.01, 0.07±0.02, 0.16±0.03 and 0.05±0.01 for lungs; 0.03±0.002, 0.06±0.02, 0.30±0.07 and 0.07±0.03 for heart; 0.03±0.005, 0.04±0.008, 0.18±0.06 and 0.04±0.007 for liver; 0.04±0.007, 0.08±0.02, 0.23±0.06 and 0.08±0.03 for kidney and 0.04±0.002, 0.05±0.005, 0.11±0.02 and 0.04±0.002 for intestine (p < 0.05 between WT-LPS and TG-LPS groups in all 5 organs). LPS mice had reduced tissue W/D ratio in all 5 organs. We conclude that endothelial-selective blockade of NF-κB is effective in preventing endotoxemic multiple organ injury.