Effect of NF-kappaB and p38 MAPK in activated monocytes/macrophages on pro-inflammatory cytokines of rats with acute pancreatitis.

Abstract

Proinflammatory cytokines TNF-alpha and IL-6 play a main role in acute pancreatitis (AP). Cytokine biosynthesis runs through two major signaling pathways at the level of proteins: nuclear transcription factor-kappaB (NF-kappaB) and p38 mitogen-activated protein kinase (p38 MAPK). The aim of the study was to investigate the effect of NF-kappaB and p38 MAPK in activated monocytes/macrophages on cytokines of rats with acute pancreastitis. Taurocholate (3% and 5%) at doses of 1 mL/kg was administered into the biliopancreatic duct of male Sprague-Dawley (SD) rats to reduce acute edematous pancreariris (AEP) and acute necrotizing pancreatitis (ANP). Pancreatic tissues were prepared immediately after death. At this point, blood was obtained for determination of serum amylase and pro-inflammatory TNF-alpha and IL-6. Activated monocytes/macrophages were captured from blood and so were ascites. NF-kappaB and p38 MAPK in activated monocytes/macrophages were measured by immunohistochemistry method. Pancreatic tissue samples were prepared for routine light microscopy, using hematoxylin and eosin (HE) staining. The serum levels of amylase were 3,056.00+/-1,232.35 IU/L and 4,865.12+/-890.34 IU/L at 3 and 6 hours in ANP group, which were significantly higher than those (3,056.00+/-1,232.35 IU/L and 3,187.17+/-821.16 IU/L) (P<0.05, respectively) in AEP group. In ascites the levels were 3.32+/-1.01 g and 3.76+/-1.12 g at 3 and 6 hours in ANP group, which were significantly higher than those (1.43+/-1.02 g and 2.56+/-1.21 g) (P<0.05, respectively) in AEP group. The serum levels of TNF-alpha were 54.27+/-23.48 pg/ml and 67.83+/-22.02 pg/ml in AEP group and 64.28+/-20.79 pg/ml and 106.59+/-43.71 pg/ml in ANP group, and the serum levels of IL-6 were 428.12+/-140.30 pg/ml and 420.13+/-139.40 pg/ml in AEP group and 1,600.32+/-309.78 pg/ml and 2,203.76+/-640.85 pg/ml in ANP group, which were far significantly higher than those in sham group (P<0.001, respectively). The serum level of TNF-alpha 6 hours after establishment of the studied model and that of IL-6 at 3 and 6 hours in ANP group were significantly higher than those in AEP (P<0.05, P<0.001, P<0.05). In ANP group, the levels of serum TNF-alpha and IL-6 6 hours after establishment of the studied model were significantly higher than those 3 hours after establishment of studied model (P<0.05, P<0.05, respectively). Three and 6 hours after establishment of the model, typical pathological changes of AEP and ANP were found, such as large numbers of inflammatory cells, edema, hemorrhage, necrosis, large amount of ascites. In AEP, NF-kappaB and p38 MAPK in activated monocytes/macrophages were moderately found at 3 and 6 hours after introduction of the model. However, in ANP, the expression of NF-kappaB and p38 MAPK in activated monocytes/macrophages was upregulated evidently at 3 and 6 hours after introduction of the model, reaching their highest levels at 6 hours after introduction of the model, which were consistent with the levels of TNF-alpha and IL-6. Cytokine TNF-alpha and IL-6 play a main role in acute pancreatitis, expression of NF-kappaB and p38 MAPK in activated monocytes/macrophages might play a major role in cytokine transcription and biosynthesis.