Up-regulation of TNF alpha mRNA in the rat spleen following induction of acute pancreatitis.

Tumor necrosis factor-alpha (TNF alpha) is postulated to be a mediator of the systemic complications associated with acute pancreatitis. Neutralization of TNF alpha with monoclonal antibody ameliorates the morbidity and mortality associated with acute pancreatitis in a rat model. Although high levels of TNF alpha are measurable in peripheral blood in acute pancreatitis, specific sites of TNF alpha production in this disease have not been described. In this study we show that induction of pancreatitis causes up-regulation of TNF alpha messenger RNA (mRNA) at a distant organ site, the spleen. Hemisplenectomies were performed in male Sprague-Dawley rats prior to induction of pancreatitis by pancreatic duct infusion of artificial bile. Completion hemisplenectomies were then performed at 30 min, 1 hr, and 2 hr after pancreatitis induction. Quantitation of TNF alpha mRNA in the hemispleens before and after pancreatitis using a semiquantitative reverse transcriptase-polymerase chain reaction method revealed an 80-fold increase in amount of TNF alpha mRNA by 2 hr after induction of pancreatitis. By contrast, control rats receiving a sham operation showed no significant increase in TNF alpha mRNA expression after infusion of the pancreatic duct with saline. The increase in TNF alpha mRNA production was associated with increased serum TNF alpha product levels and was independent of endotoxin. We conclude that severe acute pancreatitis in the rat model is associated with significant up-regulation of TNF alpha mRNA in splenic mononuclear cells. These data provide evidence that the local events of acute pancreatitis can induce up-regulation of TNF alpha mRNA at a distant site and suggest a possible mechanism of pathogenesis of the systemic manifestations of this disease.