Abstract 589: Endothelial Selective NF-κB Blockade Ameliorates Multiple Organ Injury and Preserves Bacterial Clearance Capacity in an E. coli Model of Sepsis
Our previously studies assessed multiple organ injury (MOI) using LPS and CLP models, and bacterial clearance capacity (BCC) using bacterial model (Circulation, 114: II-257; Circulation, 116: II-632). The differential effects of endothelial NF-κB blockade on septic MOI and BCC could have resulted from differences in stimulation and animal models. The hypothesis that endothelial selective blockade of NF-κB pathway ameliorates septic MOI and preserves host defense responses simultaneously has not been directly tested and formally proven. To address this question, we injected Wild type (WT) and TG mice that conditionally overexpress a mutant I-κBα selectively on endothelium with saline (1 ml/kg) or live E. coli (108 CFU per mouse, i.p.), and assessed MOI and BCC on the same groups of WT and TG mice. All mice were fed with doxycyline prior to experiments. Compared with WT-con and TG-con mice, WT-Ecoli mice had markedly increased adhesion molecule expression in multiple organs, which reduced significantly in TG-Ecoli mice. Reduced adhesion molecule expression resulted in reduced neutrophil infiltration and endothelial permeability. Tissue myeloperoxidase activity (U/g tissue) for WT-con, TG-con, WT-Ecoli and TG-Ecoli was 1.4±0.1, 1.5±0.2, 4.5±0.5 and 2.4±0.3 for lungs; 0.4±0.04, 0.3±0.06, 1.4±0.2 and 0.8±0.2 for liver; and 0.4±0.02, 0.3±0.04, 0.8±0.07 and 0.6±0.04 for kidney (p < 0.05 between WT-Ecoli and TG-Ecoli groups). Tissue Evans blue dye leakage index (mg/g tissue) for WT-con, TG-con, WT-Ecoli and TG-Ecoli was 0.05±0.01, 0.07±0.02, 0.15±0.03 and 0.07±0.01 for lungs; 0.03±0.005, 0.03±0.008, 0.08±0.007 and 0.05±0.01 for liver; and 0.04±0.007, 0.07±0.01, 0.16±0.01 and 0.1±0.02 for kidney (p < 0.05 between WT-Ecoli and TG-Ecoli groups). Compared with WT-Ecoli mice, TG-Ecoli mice showed a significantly reduced tissue wet/dry ratio in all organs, and improved survival. E. coli colony counts in blood, and in lungs, liver, spleen, and kidney homogenate were identical in the 4 groups of mice. We conclude that endothelial-selective inhibition of NF-κB activation prevents septic MOI and preserves BCC.
Supported by NIH GM063907.