BACKGROUND: Traditional Chinese medicine is a potent agent in the management of clinical and experimental acute pancreatitis (AP), but the molecular mechanism of its therapeutic action is unclear. Numerous experimental and clinical studies have shown that platelet endothelial cell adhesion molecule-1 (PECAM-1) is pivotal to leukocyte recruitment, which results in microcirculatory injury during inflammation, but its role in acute pancreatitis is poorly understood. We investigated the effects of a compound of traditional Chinese medicine pancreatitis-1 (TCMP-1) on the changes of platelet endothelial cell adhesion molecule-1 (PECAM-1) expression on polymorphonuclear leukocytes (PMNs) in acute edematous pancreatitis (AEP).
METHODS: The model of acute pancreatitis was established by subcutaneous injection of caerulein, and TCMP-1 treated groups were given TCMP-1 by catheterization from mouth to stomach (20 ml/kg) immediately after first time subcutaneous injection of caerulein. The changes of expression of PECAM-1 on leukocytes from the blood of the splenic vein and inferior vena cava were determined by flow cytometry.
RESULTS: In the AEP group, expression of PECAM-1 on PMNs was not significantly different between pancreatic microcirculation and systemic circulation at AEP2h and AEP4h time point. Then from AEP4h time point to AEP8h time point, expression of PECAM-1 was up-regulated in systemic circulation while it was down-regulated in pancreatic microcirculation and was significantly different between pancreatic microcirculation and systemic circulation at AEP8h time point (P<0.05). In the TCMP-1 treated group, compared with the AEP group, expression of PECAM-1 on PMNs decreased in different levels between pancreatic microcirculation and systemic circulation and was of significant difference at AEP8h time point (P<0.05).
 CONCLUSION:  Inhibition of PECAM-1 expression on PMNs may prevent PMNs from transmigration through the endothelium and may be one of the treatment mechanisms of TCMP-1 decoction on AEP.