Submitted on July 20, 2007
Accepted on October 4, 2007
Prostaglandin E2 modulates TNF
induced MCP-1 synthesis in pancreatic acinar cells in a PKA dependent manner
Li-Kang Sun1, Theresia V Reding1, Martha Bain1, Mathias Heikenwalder2, Daniel R Bimmler1, and Rolf Graf1*
1 Visceral & Transplantation Surgery, University Hospital Zurich, Zurich, Switzerland
2 Pathology, University Hospital, Zurich, Switzerland
* To whom correspondence should be addressed. E-mail: rolf.graf{at}usz.ch.
Introduction: COX-2 is increased in human chronic pancreatitis. We recently demonstrated in a model of chronic pancreatitis (WBN/Kob rat) that inhibition of COX-2 activity reduces and delays pancreatic inflammation and fibrosis. MCP-1 mRNA and PGE2 were significantly reduced, correlating with a decreased infiltration of macrophages. MCP-1 plays an important role in the recruitment of macrophages to the site of tissue injury. The aim of our study is to identify mechanisms by which macrophages and acinar cells maintain an inflammatory reaction.
Methods: The expression profile of E prostanoid receptors EP1-4 and MCP-1 was analyzed by RT-PCR from pancreatic specimens and AR42J cells. MCP-1 secretion was detected by ELISA from rat pancreatic lobuli.
Results: We determined EP1-4 mRNA levels in WBN/Kob rats with chronic pancreatic inflammation. Individual isoforms were highly increased in rat pancreas, concurrent with MCP-1 mRNA expression. In supernatants of pancreatic lobuli and AR42J cells, MCP-1 was detectable by ELISA. In the presence of TNF
, MCP-1 was up-regulated. Co-incubation with PGE2 enhanced the TNF-induced MCP-1 synthesis significantly.Similarly, TNF mRNA was synergistically up-regulated by TNF and PGE2. Furthermore, the synergistic effect of TNF and PGE2 was abolished by inhibition of PKA, but not of PKC.
Conclusions: We conclude that EP receptors are up-regulated during chronic pancreatic inflammation. PGE2 modulates the TNF induced MCP-1 synthesis and secretion from acinar cells. This synergistic effect is PKA controlled. This mechanism might explain the COX-2 dependent propagation of pancreatic inflammation.
