Relationship between peritoneal macrophages and inflammatory reaction in a rat model of severe acute pancreatitis

Objective: To investigate the relationship between peritoneal macrophages (PMAs) and inflammatory reaction in a rat model of severe acute pancreatitis (SAP). Methods: Sprague-Dawley rats were randomly divided into control group and SAP group. To induce SAP in rats, 40 g/L sodium taurocholate (0.1 mL/100 g) was injected into the pancreatic duct through retrograde exposure of pancreatic bile duct in hepatic porta. One-third of rats were sacrificed at 3, 6 or 12 h after modeling. PMAs were extracted, and incubated for 24 h in a humidified 5% carbon dioxide incubator. The expressions of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) mRNA in PMAs were measured by semi-quantitative RT-PCR. The levels of TNF-α and IL-1β in culture medium and serum were evaluated. The histological changes of pancreas were examined. Results: The expressions of TNF-α mRNA and IL-1β mRNA in PMAs were significantly higher in SAP group than in control group at each time point (P<0.01). The concentrations of TNF-α and IL-1β in culture medium and serum were significantly elevated in SAP group compared with control group (P<0.01). The histological analysis of pancreas indicated that the damage was more severe in SAP group than in control group (P<0.01). Conclusion: PMAs secrete cytokines into pancreatitis-associated ascitic fluid, and this study demonstrates a correlation between SAP and the activation of PMAs.