Background: Transcription factor activation may be a pivotal step in the pathophysiology of sepsis syndrome and adult respiratory distress syndrome. This study investigated the activation of lung nuclear factor kappaB (NFkappaB) and nuclear factor interleukin-6 (NF-IL6) and how they correlate to proinflammatory cytokine expression and mortality in a murine model of cecal ligation and puncture (CLP).
Methods: Polymicrobial sepsis was induced by CLP. Transcription factor activation was assessed at 0, 1, 2, 3, 4, 5, 6, 8, and 24 hours after CLP by the electrophoretic mobility-shift assay. Lung cytokine mRNA levels were established by reverse transcriptase-polymerase chain reaction.
Results: CLP induced pulmonary NFkappaB activation at 3, 4, and 8 hours (p < 0.05). Lung NFkappaB activation peaked at 3 hours (533% vs. no surgery, 2,900% vs. sham treatment) after CLP. Supershift analysis revealed a predominance of p50 subunits in the lung nuclear extracts of septic mice 3 hours after CLP, indicating the presence of p50 homodimer. In contrast, liver nuclear extracts from septic mice indicated the presence of both p65 and p50 subunits at 3 hours. Lung NF-IL6 activation (p < 0.05) was observed at 4 hours (649% vs. no surgery, 296% vs. sham treatment) and 6 hours after CLP. Lung tumor necrosis factor-alpha mRNA levels were increased (p < 0.05) at all time intervals after CLP. Lung IL-6 mRNA levels were increased at 3, 6, and 8 hours after CLP.
Conclusion: Early activation of lung NFkappaB and NF-IL6 and lung cytokine mRNA expression correlated with mortality in polymicrobial sepsis. Although IL-6 mRNA levels correlated with NFkappaB and NF-IL6 activation, tumor necrosis factor-alpha mRNA levels did not, in that they preceded transcription factor activation. These data suggest a potential role for NFkappaB and NF-IL6 activation in the initiation and propagation of acute lung injury.