Amplification of the proinflammatory transcription factor cascade increases with severity of uncontrolled hemorrhage in swine

Abstract : Hypotension causes diffuse liver injury accompanied by increased local production of interleukin-6 (IL-6) in swine models of uncontrolled hemorrhagic shock (HS). IL-6 is transcriptionally upregulated by nuclear factor (NF)- B and results in activation of signal transducer and activator of transcription-3 (Stat3) in a murine model of controlled HS. Our objectives were: 1) to determine if increased IL-6 production and NF- B and Stat3 activation occurs in a swine model of uncontrolled HS, and 2) to assess whether or not levels of IL-6 mRNA and activity of NF- B and Stat3 correlate with shock severity. Materials and methods. Swine were assigned to four groups: 1) control animals (n = 6): no intervention, 2) sham operation (n = 6): celiotomy and splenectomy, 3) uncontrolled hemorrhagic shock (UHS) (n = 6): sham plus grade V vascular liver injury and resuscitation, 4) profound uncontrolled hemorrhagic shock (PUHS) (n = 8): UHS after dilutional hypothermia. Following euthanasia at 2 h, livers were harvested, total RNA isolated, and IL-6 mRNA levels quantified by Q-RT-PCR (ABI Prism 7700, Applied Biosystems International, Foster City, CA). Protein was extracted for measurement of NF- B and Stat3 activity by electrophoretic mobility shift assay (EMSA). Results. Compared to shams, IL-6 mRNA levels increased 4.5 fold in UHS and 90-fold in PUHS (P less than 0.001). Compared with shams; NF-kB activity increased 2-fold in both UHS and PUHS (P less than 0.05). Stat3 activity was equivalent (not significant) in UHS when compared with shams but increased 5.3-fold in PUHS (P less than 0.05). Conclusion. These findings suggest that regional proinflammatory cytokine production results from and perpetuates a proinflammatory transcription factor cascade in a swine model of uncontrolled hemorrhagic shock and indicate that this process is proportional to the severity of shock.