Role of calcium in substance P-induced chemokine synthesis in mouse pancreatic acinar cells.

BACKGROUND AND
PURPOSE: Substance P (SP) and chemokines play critical roles in acute pancreatitis. SP elevates cytosolic calcium in pancreatic acinar cells and elevated cytosolic calcium is thought to be an early event in the pathogenesis of acute pancreatitis. SP induces production of chemokines MCP-1, MIP-1alpha and MIP-2 in pancreatic acinar cells, however the exact mechanism by which SP stimulates the production of these pro-inflammatory mediators remain undetermined. The aim of the present study is to investigate the role of calcium in SP-induced chemokine production in pancreatic acinar cells and to establish the signal transduction mechanisms involved. EXPERIMENTAL APPROACH: An in vitro model of isolated mouse pancreatic acinar cells was used. Western blotting analysis, ELISA and calcium measurement were performed. KEY
RESULTS: SP increased chemokine secretion through the activation of PKCalpha/betaII, MAPKinases (ERK and JNK), NFkappaB and AP-1 in pancreatic acinar cells. These effects were blocked by pretreatment of the cells with the specific calcium chelator BAPTA-AM. Moreover, SP-induced activation of PKCalpha/betaII, ERK, JNK, NF-kappaB, AP-1 and chemokine production was inhibited by the specific phospholipase C inhibitor U73122. CONCLUSIONS AND IMPLICATIONS: SP-induced chemokine production in pancreatic acinar cells resulted from PLC-induced elevated intracellular calcium and PKCalpha/betaII activation, subsequently leading to the activation of MAPKinases (ERK and JNK) and transcription factors NF-kappaB and AP-1. The present study demonstrates the critical role of calcium in SP-induced chemokine production in pancreatic acinar cells. Drugs targeting the SP-calcium mediated signaling pathways could prove beneficial in improving the treatment of acute pancreatitis.