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W Denham

Publications and source records attributed to W Denham.

22 records · Page 2Linked to original sources
PubMed1997

Small molecule inhibition of tumor necrosis factor gene processing during acute pancreatitis prevents cytokine cascade progression and attenuates pancreatitis severity.

The morbidity and mortality associated with acute pancreatitis are primarily a result of pancreatic parenchymal necrosis and the development of marked pulmonary dysfunction. Recent evidence suggests that both of these conditions are propagated by interleukin (IL)-1 beta and tumor necrosis factor (TNF)-alpha, which are produced in large quantities within these organs. Because the generation of these cytokines occurs in a predictable manner early in the development of acute pancreatitis, we aimed to determine whether cytokine gene processing could be inhibited in vivo and what effects this would have on pancreatitis severity. Mild [caerulein, 50 micrograms/kg/hour intraperitoneally (IP) x 4; n = 40] or severe (choline-deficient diet; n = 40) necrotizing pancreatitis was induced in NIH swiss mice. Animals were randomly given a novel small molecule (CNI-1493; 10 mg/kg IP) known to inhibit macrophage production of TNF and IL-1 in vitro by inhibiting translation of TNF mRNA into protein. Control animals received IP vehicle. All animals with acute pancreatitis showed dramatic up-regulation of the IL-1 beta and TNF-alpha genes. Those animals receiving CNI-1493 demonstrated attenuated production of both species of mRNA in pancreatic as well as pulmonary tissue (P < 0.01). Markers of pancreatitis severity such as serum amylase and lipase, as well as pancreatic necrosis, were decreased in animals treated with CNI-1493 (all P < 0.05). Posttranscriptional blockade of TNF production precludes induction of the proinflammatory cytokine cascade that normally occurs during acute pancreatitis. This lack of cytokine gene processing in the pancreas and lungs results in dramatic reductions in tissue damage and pancreatitis severity, which is not model dependent. This is the first time that a small molecule has been shown to influence this disease.

Amylases↗
PubMedDate not supplied

Specific pancreatic enzymes activate macrophages to produce tumor necrosis factor-alpha: role of nuclear factor kappa B and inhibitory kappa B proteins.

The triggering events by which mononuclear cells throughout the body are induced to produce large amounts of cytokines during acute pancreatitis are unclear. However, recent work in our laboratory demonstrated that three specific pancreatic enzymes (elastase, carboxypeptidase A, and lipase) induced dramatic tumor necrosis factor-alpha (TNF-alpha) protein production from macrophages, whereas all others could not. This series of experiments was designed to examine the second messenger system by which this occurs. The rat macrophage cell line NR8383 was incubated for 3 hours with elastase, carboxypeptidase A, lipase, trypsin, or lipopolysaccharide (positive control). Activation of nuclear factor kappa B (NF-kappa B) was demonstrated by electrophoretic mobility shift assay, presence of inhibitory kappa B alpha and beta (I kappa B-alpha and I kappa B-beta) by Western blot analysis, and TNF-alpha protein production by enzyme-linked immunosorbent assay. Elastase, carboxypeptidase A, and lipase induced degradation of I kappa B-beta (but not I kappa B-alpha), activation of NF-kappa B, and production of TNF-alpha protein, whereas inhibition of I kappa B with pyrrolidine dithiocarbamate attenuated this response. Trypsin was unable to elicit any of these responses. Macrophages can be induced by specific activated pancreatic enzymes-elastase, carboxypeptidase A, and lipase-to produce TNF-alpha. This process is dependent on I kappa B-beta degradation and NF- kappa B activation, suggesting that these enzymes trigger this second messenger system through specific membrane-bound receptors.

Acute Disease↗
PubMedDate not supplied

Cationic liposome-mediated gene transfer during acute pancreatitis: tissue specificity, duration, and effects of acute inflammation.

Production of inflammatory cytokines in the pancreas, lung, and liver is believed to play a major role in the development of severe pancreatitis. This tissue-specific production could lend itself to directed anti-cytokine gene therapy if an appropriate delivery system could be developed. This study was undertaken to examine a novel approach for the delivery of protein-based therapies to the tissues involved during acute pancreatitis. Healthy mice received an intraperitoneal injection of cationic liposomes and a DNA plasmid containing the chloramphenicol acetyltransferase (CAT) reporter gene. Animals were killed at 12 hours and 1, 2, 3, 7, and 14 days with serum, pancreas, lung, and liver harvested. Acute pancreatitis was induced (cerulein, 50 micrograms/kg/hr intraperitoneally x4) in additional mice before or after CAT transfection. The presence of pancreatitis was established in all animals by histologic scoring of pancreata and by serum amylase and lipase levels. CAT transfection efficiency was determined by quantitative CAT enzyme activity within tissue homogenates. Animals that received the liposome were successfully transfected with the CAT gene into the pancreas, lungs, and liver. Maximal transfection in each tissue occurred at 12 hours with decreasing CAT activity over the ensuing 14 days. No healthy animals receiving the CAT gene developed elevations in amylase, lipase, or any histologic parameter of pancreatitis. Transfection efficiency in the pancreas was markedly increased by preexisting or delayed induction of pancreatitis, whereas transfection of the lung and liver was increased to a lesser extent. Gene transfection into the pancreas, liver, and lungs is possible using a cationic liposome delivery system that does not induce pancreatitis or pancreatic inflammation. Pancreatic expression of the gene product is equal to or greater than that of the organs of the reticuloendothelial system and continues at very high efficiency rates during acute pancreatitis.

Acute Disease↗