Inflammatory mediators in acute pancreatitis

Ethanol metabolism and transcription factor activation in pancreatic acinar cells in rats

BACKGROUND & AIMS

Ethanol metabolism by pancreatic acinar cells and the role of its metabolites in ethanol toxicity to the pancreas remain largely unknown. Here, we characterize ethanol metabolism in pancreatic acinar cells and determine the effects of ethanol metabolites on nuclear factor kappa B (NF-kappa B) and activator protein (AP)-1, transcription factors that are activated in pancreatitis and mediate expression of inflammatory molecules critical for this disease.

METHODS

We measured activities of fatty acid ethyl ester (FAEE) synthase and alcohol dehydrogenase (ADH), as well as accumulation of ethanol metabolites. We measured the effects of ethanol and its metabolites on NF-kappa B and AP-1 activation by using a gel shift assay.

RESULTS

Pancreas metabolizes ethanol via both oxidative and nonoxidative pathways. Acinar cells are the main source of ethanol metabolism in the pancreas. Compared with the liver, FAEE synthase activity in the pancreas is greater, whereas that of ADH is much less. FAEEs activated NF-kappa B and AP-1, whereas acetaldehyde inhibited NF-kappa B activation. Ethanol decreased NF-kappa B binding activity in acinar cells, which was potentiated by cyanamide.

CONCLUSION

Oxidative and nonoxidative ethanol metabolites regulate transcription factors differently in pancreatic acinar cells. Ethanol may regulate NF-kappa B and AP-1 positively or negatively, depending on which metabolic pathway's effect predominates. These regulatory mechanisms may play a role in ethanol toxicity to the pancreas.

Acinar cells of the pancreas are a target of interleukin-22

Interleukin-22 (IL-22) (also reported as IL-10-related T cell-derived inducible factor, IL-TIF) is a recently identified cytokine found to signal through a receptor comprising the class II cytokine receptor family members IL-10Rbeta/CRF2-4 and IL-22R. Previous work has established that IL-10Rbeta, also a component of the IL10R complex, exhibits a broad distribution of mRNA expression. Here, we observe that IL-22R exhibits a restricted expression pattern, with highest levels of mRNA expression in pancreas and detectable expression in multiple other tissues, particularly liver, small intestine, colon, and kidney. We find that isolated primary pancreatic acinar cells and the acinar cell line 266-6 respond to IL-22 with activation of Stat3 and changes in gene transcription. IL-22 mediates robust induction of mRNA for pancreatitis-associated protein (PAP1)/Reg2 and osteopontin (OPN). PAP1 is a secreted protein related to the Reg family of trophic factors and was initially characterized as a protein elevated in pancreatitis. In vivo injection of IL-22 resulted in rapid induction of PAP1 in pancreas, a response not observed in mice deficient in IL-10Rbeta. These results support the conclusion that IL-10Rbeta is a required common component of both the IL-10 and IL-22 receptors and suggest that IL-22 may play a role in the immune response in pancreas.

Cellular markers of systemic inflammation and immune suppression in patients with organ failure due to severe acute pancreatitis

BACKGROUND

Few data are available on cellular markers of systemic inflammation and immune suppression in early acute pancreatitis. The aim of this study was to describe the cellular immune inflammatory status of patients with acute pancreatitis in relation to development of organ failure.

METHODS

Prospective study including 89 patients who presented within 72 h of onset of pain. Fifty-eight of them had mild disease (Grade I group), 19 had severe disease with no organ dysfunction (Grade II group) and 12 had severe disease with organ dysfunction (Grade III group). Serial blood samples were collected on admission and following 2 days. Phagocyte surface markers were analysed using flow cytometry.

RESULTS

The proportion of HLA-DR-positive monocytes, a marker of immune suppression, and CD11b expression level on neutrophils and monocytes, a marker of systemic inflammation, were related to Grades I-III (P for trend <0.001). In Grade III patients, the proportion of HLA-DR-positive monocytes was low on presentation, or decreased rapidly during follow-up, whereas CD11b expression levels were persistently high. L-selectin and monocyte CD14 expression levels were not related to disease severity.

CONCLUSIONS

Immune suppression develops early, rapidly and unexpectedly in patients with acute pancreatitis. Monitoring immune inflammatory status may provide the means by which to identify patients who benefit from biological response modifier therapy.

Involvement of soluble adhesion molecules in acute pancreatitis

The relationship between inflammatory cytokines and adhesion molecules in cases of acute pancreatitis was studied. Twenty-five patients were divided into three groups based on the severity of their disease as rated by the Ranson score. They were also divided into two groups according to the presence or absence of the complications of the multiorgan dysfunction syndrome (MODS) and the prognosis. As the severity of acute pancreatitis increased, the plasma levels of TNF-alpha, slCAM-1, sE-selectin, and sVCAM-1 also increased. The levels of all of these soluble adhesion molecules were significantly higher in the MODS-complicated group than in the non-MODS-complicated group. The levels of TNF-alpha, slCAM-1, and sVCAM-1 were significantly higher in patients who eventually died than in patients who survived. Significant correlations were observed between the levels of TNF-alpha and slCAM-1, between those of TNF-alpha and sVCAM-1, and between the levels of slCAM-1 and sVCAM-1. These results suggest that inflammatory cytokines stimulate the expression of adhesion molecules on the vascular endothelium and that mediators, including these adhesion molecules, are closely involved in the pathogenesis of acute pancreatitis. The plasma levels of these soluble adhesion molecules reliably reflected the severity of the disease.

Management of necrotizing pancreatitis

Infection complicating pancreatic necrosis leads to persisting sepsis, multiple organ dysfunction syndrome and accounts for about half the deaths that occur following acute pancreatitis. Severe cases due to gallstones require urgent endoscopic sphincterotomy. Patients with pancreatic necrosis should be followed with serial contrast enhanced computed tomography (CE-CT) and if infection is suspected fine needle aspiration of the necrotic area for bacteriology (FNAB) should be undertaken. Treatment of sterile necrosis should initially be non-operative. In the presence of infection necrosectomy is indicated. Although traditionally this has been by open surgery, minimally invasive procedures are a promising new alternative. There are many unresolved issues in the management of pancreatic necrosis. These include, the use of antibiotic prophylaxis, the precise indications for and frequency of repeat CE-CT and FNAB, and the role of enteral feeding.

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.