IL-6 knock-out mice exhibit resistance to splanchnic artery occlusion shock

We used IL-6 knock-out (KO) mice to evaluate a possible role for IL-6 in th e pathogenesis of splanchnic artery occlusion shock (SAO). SAO shock was in duced by clamping both the superior mesenteric artery and the celiac trunk, followed by release of the clamp, There was a marked increase in the perox ynitrite formation in the plasma of the SAG-shocked IL-6 wild-type (WT) mic e after reperfusion, Immunohistochemical examination demonstrated a marked increase in the immunoreactivity to nitrotyrosine in the necrotic ileum in shocked IL-6 WT mice. SAO-shocked WT mice developed a significant increase of tissue myeloperoxidase (MPO) and malondialdehyde (MDA) activity and mark ed histological injury to the distal ileum, SAO shock was also associated w ith a significant mortality (0% survival). Reperfused ileum tissue sections from SAG-shocked WT mice showed positive staining for P-selectin, Little s pecific staining was observed in sham-WT mice, Staining of ileum tissue obt ained from sham-operated WT mice with anti-ICAM-1 antibody showed weak but diffuse staining, demonstrating that ICAM-1 is constitutively expressed. Ho wever, after SAG shock the staining intensity increased substantially in th e ileum section from WT mice. Intensity and degree of P-selectin and ICAM-1 were markedly reduced in tissue section from SAO-shocked IL-6 KO mice. SAO -shocked IL-6 KO mice also show significant reduction of neutrophil infiltr ation into the reperfused intestine, as evidenced by reduced MIRO activity, improved histological status of the reperfused tissues, reduced peroxynitr ite formation, reduced MDA levels, and improved survival. In vivo treatment with anti-IL-6 significantly prevents the inflammatory process. Our result s clearly; demonstrate that IL-6 plays an important role in ischemia and re perfusion injury and allows the hypothesis that inhibition of IL-6 may repr esent a novel and possible strategy. Part of this effect may be due to inhi bition of the expression of adhesion molecules and subsequent reduction of neutrophil-mediated cellular injury.