Inhibition of tyrosine-kinase-mediated cellular signaling by tyrphostins AG 126 and AG556 modulates murine experimental acute pancreatitis.

BACKGROUND: The effects of the tyrosine kinase inhibitors, tyrphostin AG126 and AG556 in a murine model of acute pancreatitis are investigated. METHODS: Intraperitoneal injection of cerulein in mice resulted in a severe, acute pancreatitis, which was characterized by edema, neutrophil infiltration, tissue hemorrhage, and cell necrosis as well as elevation in the serum activities of amylase or lipase. RESULTS: Infiltration of the pancreatic tissue of these animals with neutrophils (measured as increase in myeloperoxidase activity) was associated with signs of enhanced lipid peroxidation (increased tissue levels of malondialdehyde). Immunohistochemical examination showed a marked increase in immunoreactivity for nitrotyrosine and poly (ADP-ribose) polymerase (PARP) in the pancreas of cerulein-treated mice. Pretreatment or posttreatment with tyrphostin AG126 and AG556, 2 different tyrosine kinase inhibitors, significantly reduced the degree of pancreatic inflammation and tissue injury (histologic score). In particular, the treatment with the 2 tyrosine kinase inhibitors reduced the cerulein-induced nitrotyrosine formation and PARP activation in the pancreas as well as the systemic release of tumor necrosis factor alpha. CONCLUSIONS: This study provides the first evidence that (1) prevention of the activation of protein tyrosine kinases reduces the development of acute pancreatitis, and (2) inhibition of the activity of certain tyrosine kinases may represent a novel approach for the therapy of acute pancreatitis.

Calpain I inhibitor ameliorates the indices of disease severity in a murine model of cerulein-induced acute pancreatitis.

OBJECTIVE: Nuclear factor-kappaB (NF-kappaB) is a transcription factor which plays a pivotal role in the induction of genes involved in the response to injury and inflammation. Calpain I inhibitor is a potent antioxidant which is an effective inhibitor of NF-kappaB. This study examined whether the postulate that calpain I inhibitor attenuates experimental acute pancreatitis. DESIGN AND SETTING: In a murine model we measured NF-kappaB activation, expression of intercellular adhesion molecule (ICAM) 1, nitrotyrosine, inducible nitric oxide synthase (iNOS), nuclear enzyme poly(ADP-ribose) synthetase (PARS), myeloperoxidase, malondialdehyde, amylase and lipase and determined histological evidence of lung and pancreas injury in four groups: control (saline only), cerulein, calpain I inhibitor plus cerulein and calpain I inhibitor plus saline. MEASUREMENTS AND RESULTS: Intraperitoneal injection of cerulein in mice resulted in severe, acute pancreatitis characterised by oedema, neutrophil infiltration, tissue haemorrhage and necrosis and elevated serum levels of amylase and lipase. Infiltration of pancreatic and lung tissue with neutrophils (measured as increase in myeloperoxidase activity) was associated with enhanced lipid peroxidation (increased tissue levels of malondialdehyde). Immunohistochemical examination demonstrated a marked increase in immunoreactivity for nitrotyrosine, iNOS and PARS in the pancreas and lung of cerulein-treated mice. In contrast, pre-treatment with calpain I inhibitor markedly reduced: the degree of pancreas and lung injury; upregulation/expression of ICAM-1; staining for iNOS, nitrotyrosine and PARS; and lipid peroxidation. Additionally, calpain I inhibitor treatment significantly prevented the activation of NF-kappaB as suggested by the inhibition of IkappaB-alpha; degradation in the pancreas tissues after cerulein administration. CONCLUSIONS: Taken together, our results clearly demonstrate that prevention of the activation of NF-kappaB by calpain I inhibitor ameliorates experimental murine acute pancreatitis.

Pyrrolidine dithiocarbamate reduces the severity of cerulein-induced murine acute pancreatitis.

The nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays a pivotal role in the induction of genes involved in the response to injury and inflammation. Dithiocarbamates are antioxidants that are potent inhibitors of NF-kappaB. This study tested the hypothesis that pyrrolidine dithiocarbamate (PDTC) attenuates experimental acute pancreatitis. Intraperitoneal injection of cerulein in mice resulted in severe, acute pancreatitis characterized by edema, neutrophil infiltration, tissue hemorrhage and necrosis, and elevated serum levels of amylase and lipase. Infiltration of pancreatic and lung tissue with neutrophils (measured as increase in myeloperoxidase activity) was associated with enhanced lipid peroxidation (increased tissue levels of malondialdehyde). Immunohistochemical examination demonstrated a marked increase in immunoreactivity for nitrotyrosine and intracellular adhesion molecule-1 in the pancreas and lung of cerulein-treated mice. In contrast, the degree of 1) pancreas and lung injury, 2) upregulation/expression of intracellular adhesion molecule-1, 3) staining for nitrotyrosine, and 4) lipid peroxidation was markedly reduced by pretreatment with PDTC. This study demonstrates that prevention of the activation of NF-kappaB by PDTC ameliorates the tissue injury associated with experimental murine acute pancreatitis and provides an important insight into the molecular biology of acute pancreatitis.