Vjekoslav Zaninovic

Pancreatic acinar cells produce, release, and respond to tumor necrosis factor-alpha. Role in regulating cell death and pancreatitis.

The aim of this study was to determine whether tumor necrosis factor-alpha (TNFalpha) and receptors for TNFalpha are expressed in the exocrine pancreas, and whether pancreatic acinar cells release and respond to TNFalpha. Reverse transcription PCR, immunoprecipitation, and Western blot analysis demonstrated the presence of TNFalpha and 55- and 75-kD TNFalpha receptors in pancreas from control rats, rats with experimental pancreatitis induced by supramaximal doses of cerulein, and in isolated pancreatic acini. Immunohistochemistry showed TNFalpha presence in pancreatic acinar cells. ELISA and bioassay measurements of TNFalpha indicated its release from pancreatic acinar cells during incubation in primary culture. Acinar cells responded to TNFalpha. TNFalpha potentiated NF-kappaB translocation into the nucleus and stimulated apoptosis in isolated acini while not affecting LDH release. In vivo studies demonstrated that neutralization of TNFalpha with an antibody produced a mild improvement in the parameters of cerulein-induced pancreatitis. However, TNFalpha neutralization greatly inhibited apoptosis in a modification of the cerulein model of pancreatitis which is associated with a high percentage of apoptotic cell death. The results indicate that pancreatic acinar cells produce, release, and respond to TNFalpha. This cytokine regulates apoptosis in both isolated pancreatic acini and experimental pancreatitis.

Early NF-κB activation is associated with hormone-induced pancreatitis

Inflammation and cell death are critical to pathogenesis of acute pancreatitis. Here we show that transcription factor nuclear factor-κB (NF-κB), which regulates these processes, is activated and plays a role in rat cerulein pancreatitis. NF-κB was strongly activated in the pancreas within 30 min of cerulein infusion; a second phase of NF-κB activation was prominent at 3-6 h. This biphasic kinetics could result from observed transient degradation of the inhibitory protein IκBα and slower but sustained degradation of IκBβ. The hormone also caused NF-κB translocation and IκB degradation in vitro in dispersed pancreatic acini. Both p65/p50 and p50/p50, but not c-Rel, NF-κB complexes were manifest in pancreatitis and in isolated acini. Coinfusion of CCK JMV-180, which abolishes pancreatitis, prevented cerulein-induced NF-κB activation. The second but not early phase of NF-κB activation was inhibited by a neutralizing tumor necrosis factor-α antibody. Antioxidant N-acetylcysteine (NAC) blocked NF-κB activation and significantly improved parameters of pancreatitis. In particular, NAC inhibited intrapancreatic trypsin activation and mRNA expression of cytokines interleukin-6 and KC, which were dramatically induced by cerulein. The results suggest that NF-κB activation is an important early event that may contribute to inflammatory and cell death responses in acute pancreatitis.

Ethanol Diet Increases the Sensitivity of Rats to Pancreatitis Induced by Cholecystokinin Octapeptide

BACKGROUND & AIMS Although alcoholism is a major cause of pancreatitis, the pathogenesis of this disorder remains obscure. Failure to produce experimental alcoholic pancreatitis suggests that ethanol may only increase predisposition to pancreatitis. This study sought to develop a model of ethanol pancreatitis by determining if an ethanol diet sensitizes rats to pancreatitis caused by cholecystokinin octapeptide (CCK-8). METHODS Rats were fed intragastrically either control or ethanol diet for 2 or 6 weeks. The animals were then infused for 6 hours with either saline or CCK-8 at a dose of 3000 pmol. kg(-1). h(-1), which by itself did not induce pancreatitis. The following parameters were measured: serum amylase and lipase levels, pancreatic weight, inflammatory infiltration, number of apoptotic acinar cells, pancreatic messenger RNA (mRNA) expression of cytokines and chemokines, and nuclear factor (NF)-kappaB activity. RESULTS All measures of pancreatitis, as well as NF-kappaB activity and mRNA expression for tumor necrosis factor alpha, interleukin 6, monocyte chemotactic protein 1, macrophage inflammatory protein 2, and inducible nitric oxide synthase, were significantly increased only in rats treated with ethanol plus CCK-8. CONCLUSIONS An ethanol diet sensitizes rats to pancreatitis caused by CCK-8. The combined action of ethanol and CCK-8 results in NF-kappaB activation and up-regulation of proinflammatory cytokines and chemokines in the pancreas. These mechanisms may contribute to the development of alcoholic pancreatitis.

Amelioration of rat cerulein pancreatitis by guamerin-derived peptide, a novel elastase inhibitor.

Increased activity of various proteases is observed in both human and experimental pancreatitis; however, the information on the effects of specific protease inhibitors on the disease is limited. In this study we show that a novel elastase inhibitor, guamerin-derived synthetic peptide (GDSP), improves the parameters of cerulein-induced acute pancreatitis in the rat. The effects of GDSP on pancreatic weight, serum amylase and lipase, morphologic changes in the pancreas, neutrophil infiltration, and nuclear factor KB (NF-KB) activation were measured in rats infused with supramaximal dose of cerulein (5 (g/kg/h) for 6 h. The effects of GDSP were also measured on superoxide formation by activated human neutrophils. The effects of GDSP were compared with those of another elastase inhibitor, elastatinal. GDSP significantly inhibited edema formation, neutrophil infiltration, acinar cell damage, and plasma lipase and amylase increases caused by cerulein. GDSP also completely inhibited superoxide formation in the human neutrophils stimulated by N-formyl-methionine-leucine-phenyl-alanine (fMLP) or 12-O-tetradecanoylphorbol-13-acetate (TPA). Elastatinal had some of the same effects as GDSP but was less potent and effective. These results demonstrate a beneficial effect of GDSP, a novel specific elastase inhibitor, on the development of rat cerulein pancreatitis.