FE-999024

We evaluated a potential role for proteinase‐activated receptor 4 (PAR4) in a rodent paw inflammation model, with a focus on two main features of inflammation: (1) oedema and (2) granulocyte recruitment.A PAR4 antagonist (Pepducin P4pal‐10; palmitoyl‐SGRRYGHALR‐NH2) reduced both the oedema and granulocyte recruitment induced by a localized administration of carrageenan in the rat hind paw, pointing to a key role for PAR4 in this inflammation model.Further, intraplantar injection in the mouse hind paw of a PAR4 agonist (AYPGKF‐NH2), but not its standard PAR4‐inactive peptide control (YAPGKF‐NH2), caused an inflammatory reaction characterized by oedema (increased paw thickness) and granulocyte recruitment (increased paw myeloperoxidase activity). The PAR4 agonist‐induced effects were inhibited in mice pretreated with pepducin P4pal10.These PAR4 agonist‐mediated effects were not affected by pretreatment with inhibitors of either NO production or prostaglandin release (L‐NAME and indomethacin, respectively).However, selective immuno‐depletion of neutrophils significantly reduced PAR4 agonist‐induced oedema formation.Moreover, AYPGKF‐NH2‐induced oedema was also reduced by pretreatment with either a kinin B2 receptor antagonist (icatibant) or a tissue or plasma kallikrein inhibitor (FE999024 and FE999026, respectively), but not with a kinin B1 receptor antagonist (SSR240612).We conclude: (1) that PAR4 plays an important role in the inflammatory response as it mediates some of the hallmarks of inflammation and (2) that PAR4‐mediated oedema is dependent on the recruitment of neutrophils and components of the kallikrein–kinin system.British Journal of Pharmacology (2005) 146, 670–678. doi:10.1038/sj.bjp.0706371

In order to investigate the mechanism of kinin release leading to vascular symptoms in acute interstitial‐oedematous pancreatitis, the novel, selective inhibitors of tissue kallikrein, (2S,2′R)‐2‐(2′‐amino‐3′‐(4′‐chlorophenyl)propanoylamino)‐N‐(3‐guanidinopropyl)‐3‐(1‐naphthyl)propanoamide (FE999024, CH‐2856), and of plasma kallikrein, (2′S,2′′R)‐4‐(2′‐(2′′(carboxymethylamino)‐3′′‐cyclohexyl‐propanoylamino)‐3′‐phenyl‐propanoylamino)piperidine‐1‐carboxamidin (FE999026, CH‐4215), were used in experimental caerulein‐induced pancreatitis in rats.Oedema formation and plasma protein extravasation during the 2 h infusion of caerulein were inhibited in a dose‐dependent manner by i.p. pretreatment with FE999024 (7–60 μmol kg−1) while FE999026 had no effect at the same doses.Haemoconcentration and hypovolaemia associated with the pancreatic oedema formation during pancreatitis were significantly attenuated by FE999024 at a dose of 20 μmol kg−1. The reduction in circulating plasma volume was not affected by FE999026.Accumulation of amylase and lipase in the pancreas was dose‐dependently reduced by FE999024 while enzyme activities in the blood serum were increased by FE999024 at 60 μmol kg−1 indicating improved enzyme removal from the tissue. Enzyme activities in the tissue and in the blood remained unaffected by FE999026.FE999024 (20 μmol kg−1) largely inhibited increased tissue kallikrein‐like activity in the pancreas during acute pancreatitis and also strongly attenuated influx of plasma kallikrein into the tissue. FE999026 (20 μmol kg−1) significantly inhibited plasma kallikrein‐like activity in the pancreas but had no effect on tissue kallikrein‐like activity.In conclusion, vascular kinin‐mediated symptoms observed during oedematous pancreatitis in the rat are caused by the action of tissue kallikrein in the pancreas whereas an involvement of plasma kallikrein seems to be unlikely.British Journal of Pharmacology (2002) 137, 692–700. doi:10.1038/sj.bjp.0704910