Hepatic ischemia-reperfusion results in an acute inflammatory response culminating in the recruitment of activated neutrophils that directly injure hepatocytes. Recent evidence suggests that CD4+ lymphocytes may regulate this neutrophil-dependent injury, but the mechanisms by which this occurs remain to be elucidated. In the present study, we sought to determine the type of CD4+ lymphocytes recruited to the liver after ischemia-reperfusion and the manner in which these cells regulated neutrophil recruitment and tissue injury. Wild-type and CD4 knockout (CD4-/-) mice were subjected to hepatic ischemia-reperfusion. CD4+ lymphocytes were recruited in the liver within 1 h of reperfusion and remained for at least 4 h. These cells were comprised of conventional (alphabetaTCR-expressing), unconventional (gammadeltaTCR-expressing), and natural killer T cells. CD4-/- mice were then used to determine the functional role of CD4+ lymphocytes in hepatic ischemia-reperfusion injury. Compared with wild-type mice, CD4-/- mice had significantly greater liver injury, yet far less neutrophil accumulation. Adoptive transfer of CD4+ lymphocytes to CD4-/- mice recapitulated the wild-type response. In wild-type mice, neutralization of interleukin (IL)-17, a cytokine released by activated CD4+ lymphocytes, significantly reduced neutrophil recruitment in association with suppression of MIP-2 expression. Finally, oxidative burst activity of liver-recruited neutrophils was higher in CD4-/- mice compared with those from wild-type mice. These data suggest that CD4+ lymphocytes are rapidly recruited to the liver after ischemia-reperfusion and facilitate subsequent neutrophil recruitment via an IL-17-dependent mechanism. However, these cells also appear to attenuate neutrophil activation. Thus the data suggest that CD4+ lymphocytes have dual, opposing roles in the hepatic inflammatory response to ischemia-reperfusion.

The current study explored the concept that adult and pediatric populations differ in their response to major injury. Male C57BL/6 mice of a "young adult" (8-12 weeks) or "mature adult" (12-13 months) age were subjected to partial hepatic ischemia and reperfusion. Mature adult mice displayed significantly more liver injury than young adult mice as assessed histologically and by serum levels of alanine aminotransferase. Interestingly, there was far less neutrophil accumulation in the livers of mature adult mice. However, liver-recruited neutrophils from mature adult mice had a higher activation state than those from young adult mice. Activation of the inflammatory transcription factor, NF-kappaB, was suppressed in whole livers from mature adult mice. In isolated liver cells, Kupffer cells showed no difference in NF-kappaB activation, but hepatocytes from mature adult mice had delayed NF-kappaB activation in response to TNF. Furthermore, isolated hepatocytes from young adult mice produced abundant amounts of the chemokine, macrophage inflammatory protein-2, whereas hepatocytes from mature adult mice produced little, if any macrophage inflammatory protein-2. Mature adult mice had much lower hepatic expression of the cytoprotective protein, heat shock protein 70, than did young adult mice. In contrast, serum heat shock protein 70 levels, which has been linked to subsequent tissue injury, were higher in mature adult mice than in young adult mice. These data suggest that there are multiple alterations at the cellular and molecular levels that contribute to enhanced postischemic liver injury in mature adult mice.

Sarcoma is generally a rare disease in the US, with poor survival in patients with both primary angiosarcoma and metastatic disease from sarcoma and GIST. In order to determine if liver transplantation for sarcoma is a realistic option, we examined records of all patients in the US component of the Israel Penn International Transplant Tumor Registry were reviewed. Those patients with liver failure from primary or metastatic liver sarcoma were evaluated. Patient outcome analysis was then performed. Patient and tumor demographics were reviewed as well as patient survival after transplantation. 19 patients are identified having received liver transplantation after treatment for sarcoma of the liver, 6 patients with primary hepatic sarcoma and 13 patients with metastatic sarcoma of the liver. Recurrence was almost universal in 18 of 19 patients (95%) after a median interval of 6 months. Survival for the group as a whole was 47% for 1-year, 15% for 3-years and 5% for 5-years. Given the early recurrence of tumor and meager 1-year survival outcome, liver transplantation is a poor therapeutic choice for patients with either primary or metastatic liver sarcoma, including high-grade leiomyosarcoma (GIST) regardless of primary site or primary therapy.

Hepatic ischemia/reperfusion injury is a complication of liver resection surgery, transplantation and hypovolemic shock, leading to local and remote cellular damage and organ dysfunction. This injury is largely a result of an acute inflammatory response characterized by the induction of a cascade of proinflammatory mediators that culminates in the recruitment of leukocytes to the post-ischemic tissue leading to parenchymal cell injury. Endogenous regulatory mechanisms exist to attempt to control this inflammatory response. These include anti-inflammatory cytokines that function to suppress proinflammatory mediator expression. In this review, we address the current knowledge of the pro- and anti-inflammatory cytokine components of the acute liver inflammatory response to ischemia/reperfusion as well as how these cytokines can be manipulated to reduce post-ischemic liver injury.

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