Woody Denham

Evidence for an unknown component of pancreatic ascites that induces adult respiratory distress syndrome through an interleukin-1 and tumor necrosis factor-dependent mechanism

BACKGROUND The development of acute respiratory distress syndrome (ARDS) during acute pancreatitis is associated with interleukin (IL)-1 and tumor necrosis factor (TNF) gene expression within the pulmonary parenchyma. Although activated pancreatic enzymes have been thought to mediate pancreatitis-induced ARDS, they are not capable of inducing cytokine production in vitro. We hypothesized that IL-1 and TNF production in the lungs is essential to the development of ARDS and is induced by a mediator released from the inflamed pancreas. METHODS Pancreatic ascites was obtained from rats after induction of bile-salt pancreatitis, cultured, and assayed for IL-1, TNF, IL-6, IL-8, IL-10, interferon-gamma, and endotoxin. Sterile, cytokine-free ascites or saline (control) was subsequently administered intravenously (20 ml/kg) to healthy rats and to IL-1 R1 or TNF R1 knockout mice. RESULTS Animals administered intravenous ascites had a 30-fold rise in pulmonary IL-1 and TNF mRNA, as well as increased alveolar leukocytes and protein. Knockout animals devoid of active IL-1 or TNF receptors failed to develop increased alveolar protein or leukocytes. CONCLUSIONS A component of pancreatic ascites other than activated enzymes, bacteria, or inflammatory cytokines is capable of inducing ARDS in healthy animals. The mechanism appears to be directly attributable to the activity of pulmonary IL-1 and TNF.

Evidence of a central role for p38 map kinase induction of tumor necrosis factor α in pancreatitis-associated pulmonary injury

BACKGROUND Tumor necrosis factor alpha (TNF alpha) has been implicated as an important mediator in acute pancreatitis-associated adult respiratory distress syndrome, but the precise pathogenesis remains unclear. The purpose of this work was to clarify the role of TNF alpha that is produced within the lung parenchyma in the inducement of pancreatitis-related pulmonary injury and to examine 1 of the potential pathways leading to the production of pulmonary TNF alpha. METHODS Bile salt pancreatitis was induced in rats (n = 40) that were randomized to receive a p38 mitogen-activated protein (MAP) kinase inhibitor or vehicle. A separate group (n = 16) underwent sham operation. Pulmonary capillary permeability was determined with fluorescein isothiocyanate-labeled albumin and Evans blue dye, and lung histologic analysis was performed. TNF alpha protein was measured in bronchoalveolar lavage fluid, and p38 MAP kinase was activity determined by Western blot analysis. RESULTS The induction of pancreatitis resulted in increased pulmonary capillary leakage and worsened histologic condition (P < .01 vs sham). Effective inhibition of p38 MAP kinase-induced TNF alpha production completely prevented pancreatitis-associated pulmonary injury (P < .01 vs vehicle). CONCLUSIONS p38 MAP kinase-induced TNF alpha production plays a central role in the development of pulmonary dysfunction, which accompanies severe acute pancreatitis in this rodent model.

Directed antisense therapy confirms the role of protein kinase C–α in the tumorigenicity of pancreatic cancer

BACKGROUND The level of expression of the alpha isoform of protein kinase C (PKC-alpha) has been shown to correlate inversely with the pathologic differentiation of human pancreatic cancers. METHODS We stably transfected a moderately differentiated pancreatic cell line (HPAC) to overexpress PKC-alpha and examined the survival rates compared with parent HPAC according to an orthotopic model. Next we used a PKC-alpha antisense oligonucleotide specifically to down-regulate this isoform in vitro and examine the effect of treatment in vivo again according to the orthotopic model. RESULTS Animals implanted with the overexpressing cell line had a mortality rate almost twice that of those implanted with the parent cell line (P < .01). Treatment with antisense oligonucleotide in increasing concentrations down-regulated PKC-alpha mRNA by Northern blot analysis and reverse transcriptase-polymerase chain reaction. Animals treated with antisense oligonucleotide after orthotopic implantation of pancreatic cancer cells survived statistically longer than those treated with vehicle alone (P = .005). Treatment with a scrambled oligonucleotide also conferred a survival benefit compared with vehicle alone (P < .01). CONCLUSIONS Tumorigenicity of pancreatic cancer is related directly to PKC-alpha expression in vivo as demonstrated by decreased survival when overexpressed. PKC-alpha expression can be down-regulated directly (antisense) and indirectly (scrambled) in vitro, which subsequently confers a dramatic survival benefit in vivo.

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-α) 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-KB) was demonstrated by electrophoretic mobility shift assay, presence of inhibitory kappa B alpha and beta (IKB-a and IKB-13) by Western ~lot analysis, and TNF-α protein production by enzyme-linKed immunosorbent assay. Elastase, carboxypeptidase A, and lipase induced degradation of IKB-13 (but not IKB-a), activation of NF-KB, and production of TNF-α protein, whereas inhibition of IKB 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-α. This process is dependent on IKB-13 degradation and NF-KB activation, suggesting that these enzymes trigger this second messenger system through specific membrane-bound receptors.

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 anticytokine 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 μg/kg/hr intraperitoneally × 4) 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 pancreafitis.

INFLAMMATORY MEDIATORS IN STERILE MODELS OF INFLAMMATION : EARLY EVALUATION OF NEW MEDIATOR-DIRECTED THERAPIES

Inflammatory mediators are known to play a role in the progression of infectious models of inflammation, however, recent evidence suggests that the same mediators are responsible for the local and systemic inflammation in sterile animal models such as pancreatitis, ischemia-reperfusion or the injection of turpentine or zymosan. Using these noninfectious animal models, novel mediator-directed therapies can be critically evaluated and the subsequent data utilized to design possible clinical trials.

Potential new therapies for the treatment of acute pancreatitis

The treatment of acute pancreatitis has remained virtually unchanged for the past 50 years, in large part due to a poor understanding of the initial intracellular events. Furthermore, there is a lack of knowledge regarding the mediator(s) responsible for the progression of the disease from local pancreatic inflammation to a systemic inflammatory disease, as well as the mediator(s) responsible for distant organ dysfunction and failure. With recent advances in the pathophysiology of pancreatitis, in particular the role of the inflammatory mediators interleukin-1 beta, tumour necrosis factor alpha and platelet-activating factor, the potential for new effective therapies has been realised. At present, a number of inflammatory mediator antagonists are being tested in humans, with the hope that we may soon develop a specific treatment for a disease, which thus far, has none.