Cerulein upregulates ICAM-1 in pancreatic acinar cells, which mediates neutrophil adhesion to these cells

Pancreatic gene expression during the initiation of acute pancreatitis: identification of EGR-1 as a key regulator

We hypothesized that genes expressed in pancreatic acinar cells during the initiation of acute pancreatitis determine the severity of the disease. Therefore, we utilized microarrays to identify those genes commonly induced in rat pancreatic acinar cells within 1-4 h in two in vivo models, caerulein and taurocholate administration. This strategy yielded 51 known genes representing a complex array of molecules, including those that are likely to either reduce or increase the severity of the disease. Novel genes identified in the current study included ATF3, BRF1, C/EBPbeta, CGRP, EGR-1, ephrinA1, villin2, ferredoxin, latexin, lipocalin, MKP-1, NGFI-B, RhoA, tissue factor (TF), and syndecan. To validate these microarray results, the role of EGR-1 was further investigated using quantitative RT-PCR, Western blotting, and immunocytochemistry. EGR-1 expression occurred within acinar cells and correlated with the development of caerulein-induced acute pancreatitis in rats. Furthermore, the levels of the inflammation-related genes MCP-1, PAI, TF, IL-6, and ICAM-1 and the extent of lung inflammation were reduced during the initiation of caerulein-induced acute pancreatitis in EGR-1-deficient mice. Thus this study identified EGR-1 and several other novel genes likely to be important in the development and severity of acute pancreatitis.

Influence of platelet activating factor on expression of adhesion molecules in experimental pancreatitis

AIM: To determine whether Platelet activating factor (PAF) has a regulation role in the expression of adhesion molecules and accumulation of neutrophils in a murine model of acute pancreatitis.

METHODS: One hundred twenty-eight Kunming mice were divided into four groups. Group 1 received 0.1 mL saline s.c. every hour for three hours (sham). Group 2 received cerulein (50 μg/kg dose s.c.) every hour for three hours. Group 3 received AP and additional challenge of PAF (50 mg/kg in absolute ethanol) (AP/PAF). Group 4 received AP, plus therapeutic treatment with GAB (25 mg dose i.p.) immediately after the first challenge of cerulein (AP/GAB). Animals were sacrificed at 12 h after the first challenge of saline or cerulein. Adhesion molecules of pancreas were semi-quantified by SP methods. Standard assays were performed for serum amylase and myeloperoxidase activity (MPO) of pancreas. Histology of pancreas was scored in a blind manner. Water content of pancreas was also measured at the same time.

RESULTS: Control pancreata showed negligible adhesion molecule expression and neutrophil accumulation. There were evident adhesion molecules expression and neutrophil accumulation in AP and AP/PAF compared with sham (P < 0.05). AP/GAB had a lower level of adhesion molecules, neutrophils, and water content versus AP and AP/PAF (P < 0.05). Histology showed a trend toward improvement in AP/GAB, but did not reach statistical significance.

CONCLUSION: PAF can induce the expression of adhesion molecules that mediate neutrophil accumulation. The PAF antagonist reduces the expression of adhesion molecules and the severity of inflammation when given immediately after the induction of mild AP in mice. These results suggest that PAF antagonism may be useful in the treatment of mild pancreatitis after its clinical onset.

Effects of tetrandrine and QYT on ICAM-1 and SOD gene expression in pancreas and liver of rats with acute pancreatitis

AIM: Available experimental evidence from both clinical and animal models shows that both Chinese medicines tetrandine (Tet) and Qing Yi Tong (QYT) have positive treatment effects on acute pancreatitis (AP). This investigation was conducted to explore the treatment mechanisms of Tet and QYT on AP at the molecular level and thereby explain their therapeutic affects. It included an investigation of the effects of these drugs on gene expression of both intercellular adhesion molecule 1 (ICAM-1) and superoxide dismutase (Mn-SOD and Cu, Zn-SOD) in a rat model with AP.

METHODS: AP in the test rats was induced by subjecting them to laparotomy followed by a retrograde injection of 4% sodium taurocholate into the bilio-pancreatic duct. The test rats with AP were divided into three groups. One was treated with Tet, one with QYT, and one with normal saline solution. The sham-operated control group (SO) rats were only subjected to laparotomy. They were given no further treatment. For the Tet group, Tet was injected intraperitoneally, and for the QYT group, QYT was given with a nose-gastric catheter. These procedures were done at both 10 min and 5 h after AP induction. The levels of ICAM-1 mRNA expression and of SOD (Mn-SOD and Cu, Zn-SOD) mRNA expression in the pancreas and liver tissues were measured by RT-PCR at 1, 5, and 10 h after AP induction.

RESULTS: When compared with the SO group during the observation time, rats with AP showed a higher expression of ICAM and a lower expression of Mn-SOD in both pancreas and liver tissues, and a lower expression of Cu, Zn-SOD in the pancreas. Tet treatment attenuated changes in the expression of both ICAM-1, and SOD (Mn-SOD and Cu, Zn-SOD) to a significant degree. A similar effect on the expression of SOD (Mn-SOD and Cu, Zn-SOD) was also found in the QYT group, but no obvious suppressive effect on ICAM-1 expression was observed.

CONCLUSION: The results of this study suggest that one of the main mechanisms of Tet and QYT in treating AP is to enhance anti-oxidation of the body. The results also suggest that the anti-inflammatory effect of Tet is involved in the reduction of ICAM-1 expression. This explains why Tet and QYT are beneficial in treating AP.

Curcumin ameliorates ethanol and nonethanol experimental pancreatitis

Treatments for pancreatitis are limited. Activation of transcription factor NF-kappaB, a key regulator of inflammatory molecule expression, is an early event in experimental pancreatitis and correlates with the inflammatory response. We report here that curcumin, a natural phytochemical known to inhibit NF-kappaB and activator protein (AP)-1, another important proinflammatory transcription factor, ameliorates pancreatitis in two rat models. In both cerulein pancreatitis and pancreatitis induced by a combination of ethanol diet and low-dose CCK, curcumin improved the severity of the disease as measured by a number of parameters (histology, serum amylase, pancreatic trypsin, and neutrophil infiltration). Curcumin markedly inhibited NF-kappaB and AP-1 activation, assessed by DNA binding and degradation of inhibitory IkappaB proteins, and the induction of mRNAs for cytokines IL-6 and TNF-alpha, the chemokine KC, and inducible nitric oxide synthase in pancreas. Curcumin also blocked CCK-induced NF-kappaB and AP-1 activation in isolated pancreatic acini. Our findings indicate that blocking key signals of the inflammatory response ameliorates pancreatitis in both ethanol and nonethanol models. They suggest that curcumin, which is currently in clinical trials for cancer prevention, may be useful for treatment of pancreatitis.

From acinar cell damage to systemic inflammatory response: current concepts in pancreatitis

Acute pancreatitis represents a local inflammatory disorder with severe systemic consequences. Significant progress in understanding the pathophysiology of acute pancreatitis has been achieved in recent years. However, there is no clear concept about initialization and propagation of the disease both in experimental models and in humans. Furthermore, reliable strategies to evaluate prognosis and perform therapy are still missing. The review focuses on mechanisms originating from acinar cells leading to a systemic inflammatory response in experimental pancreatitis.

Neutrophils and NADPH oxidase mediate intrapancreatic trypsin activation in murine experimental acute pancreatitis

BACKGROUND & AIMS

Intrapancreatic activation of digestive enzymes is a key event in the parenchymal cell injury of pancreatitis. We hypothesized that neutrophils recruited to the pancreas during pancreatitis may contribute to such activation.

METHODS

To cause experimental pancreatitis, rats and mice were treated with high doses of cerulein. Activation of the digestive enzyme, trypsin, was measured in pancreatic homogenates using a fluorogenic assay and localized immunocytochemically with antibody to trypsin-activation peptide (TAP).

RESULTS

Compared with controls, rats depleted of neutrophils with antineutrophil serum exhibited a marked attenuation in intrapancreatic trypsin activation and acinar cell TAP labeling induced by high-dose cerulein. To examine the mechanism, mice deficient in either nicontinamide adenine dinucleotide phosphate (NADPH) oxidase, or myeloperoxidase (MPO) were studied for trypsin activation. Mice deficient in NADPH oxidase exhibited attenuation of the cerulein-induced trypsin activation, but those deficient in MPO did not. Using measurements of Western blot analysis, generation of reactive oxygen species, and immunocytochemistry, we demonstrated the NADPH oxidase activity is in neutrophils and not pancreatic acinar tissue.

CONCLUSIONS

The results demonstrate a novel role for neutrophils infiltrating the pancreas in pathologic activation of digestive enzymes in acute pancreatitis and indicate that this effect is mediated by products of NADPH oxidase.

Localized pancreatic NF-kappaB activation and inflammatory response in taurocholate-induced pancreatitis

Transcription factor nuclear factor-kappaB (NF-kappaB) is activated in cerulein pancreatitis and mediates cytokine expression. The role of transcription factor activation in other models of pancreatitis has not been established. Here we report upregulation of NF-kappaB and inflammatory molecules, and their correlation with local pancreatic injury, in a model of severe pancreatitis. Rats received intraductal infusion of taurocholate or saline, and the pancreatic head and tail were analyzed separately. NF-kappaB and activator protein-1 (AP-1) activation were assessed by gel shift assay, and mRNA expression of interleukin-6, tumor necrosis factor-alpha, KC, monocyte chemoattractant protein-1, and inducible nitric oxide synthase was assessed by semiquantitative RT-PCR. Morphological damage and trypsin activation were much greater in the pancreatic head than tail, in parallel with a stronger activation of NF-kappaB and cytokine mRNA. Saline infusion mildly affected these parameters. AP-1 was strongly activated in both pancreatic segments after either taurocholate or saline infusion. NF-kappaB inhibition with N-acetylcysteine ameliorated the local inflammatory response. Correlation between localized NF-kappaB activation, cytokine upregulation, and tissue damage suggests a key role for NF-kappaB in the development of the inflammatory response of acute pancreatitis.

Activation of pancreatic acinar cells on isolation from tissue: cytokine upregulation via p38 MAP kinase

Cytokines produced by pancreatic acinar cells may mediate cell death and recruitment of inflammatory cells into pancreas in pancreatitis and other disorders. Here, we demonstrate mRNA expression for a number of cytokines in acini isolated from rat pancreas. Using RNA from microscopically selected individual cells, we confirmed the acinar cell as a source for cytokine expression. Competitive RT-PCR, Western blot analysis, and immunocytochemistry showed large amounts of monocyte chemotactic protein-1 and interleukin-6 compared with other cytokines. Cytokine expression was inhibited by either inhibitors of p38 mitogen-activated protein kinase (MAPK), SB-202190 and SB-203580, or (less strongly) by the transcription factor nuclear factor (NF)-kappaB inhibitor MG-132. A combination of SB-203580 and MG-132 inhibited mRNA expression of all cytokines by >90%. The results suggest a major role for p38 MAPK and involvement of NF-kappaB in cytokine expression in pancreatic acinar cells. In contrast to isolated acini, we detected no or very low cytokine expression in normal rat pancreas. Our results indicate that activation of p38 MAPK, transcription factors, and cytokines occurs during removal of the pancreas from the animal and isolation of acini.