Differential oxidative injury in extrapancreatic tissues during experimental pancreatitis: modification of lung proteins by 4-hydroxynonenal

Free radicals and acute pancreatitis: much ado about … something

There is a convincing body of evidence that oxidative stress is involved in the pathogenesis of acute pancreatitis. The effects of different radical scavengers suggested that reactive oxygen metabolites are generated at very early stage of disease and contribute to amplify the pancreatic damage. Oxidative stress is also involved in the progression of the disease from a local damage to a systemic organ failure. However, therapeutic use of antioxidants failed to clearly show a clinical benefit in different trials. Therefore, although antioxidants alone seem to be not enough for the treatment of severe acute pancreatitis, future combined therapeutic strategies should include antioxidants in its composition.

Antioxidant therapy in acute pancreatitis: experimental and clinical evidence

SIGNIFICANCE

Oxidative stress plays an important role in the pathogenesis of both acute and chronic pancreatitis. Although its impact is well investigated and has been studied clinically in chronic pancreatitis, it is less well defined for acute pancreatitis.

RECENT ADVANCES

Pathophysiological aspects of oxidative stress in acute pancreatitis have shown that reactive oxidative species (ROS) participate in the inflammatory cascade, and mediate inflammatory cell adhesion and consecutive tissue damage. Furthermore, ROS are involved in the generation of pain as another important clinical feature of patients suffering from acute pancreatitis.

CRITICAL ISSUES

Despite sufficient basic and experimental knowledge and evidence, the step from bench to bedside has not been successfully performed. Only a limited number of clinical studies are available that can give convincing evidence for the use of antioxidants in the clinical setting of acute pancreatitis.

FUTURE DIRECTIONS

Future studies are required to evaluate potential benefits of antioxidative substances to attenuate the severity of acute pancreatitis. Special focus should be put on the aspect of pain generation and the progression from mild to severe acute pancreatitis in the clinical setting.

Potential role of reactive oxygen species in pancreatitis-associated multiple organ dysfunction

BACKGROUND

Severe acute pancreatitis is still associated with substantial morbidity and mortality. Experimental and clinical studies have demonstrated that reactive oxygen species (ROS) represent early occurring inflammatory mediators contributing to cell dysfunction, both locally in the pancreas and remote organs.

METHOD

A systematic literature review was conducted to investigate the potential roles of intra- and intercellular, as well as interorgan signaling of ROS in the development of pancreatitis-associated multiple organ dysfunction syndrome (MODS). A text word search of the Medline, PubMed and Cochrane databases, and a manual search of the citations from these references, was performed.

RESULTS

ROS directly compromise cellular damage and regulate intercellular signals in pancreatitis-associated MODS. ROS are involved in leukocyte activation, production of cytokines, endothelial barrier dysfunction, and microcirculatory barrier dysfunction in acute pancreatitis. Beside effects on intercellular signaling, ROS also affect intracellular events and activate the transcription factor nuclear factor kappa B that regulates inflammatory cytokine expression.

CONCLUSION

ROS is a critical factor responsible for the development of pancreatitis-induced remote organ dysfunction via intercellular and interorgan signaling. The role of antioxidant treatment, included as a part of multimodal management, remains to be investigated.

Effect of NF-κB and p38 MAPK in activated monocytes/macrophages on pro-inflammatory cytokines of rats with acute pancreatitis

AIM: Proinflammatory cytokines TNF-α and IL-6 play a main role in acute pancreatitis (AP). Cytokine biosynthesis runs through two major signaling pathways at the level of proteins: nuclear transcription factor-κB (NF-κB) and p38 mitogen-activated protein kinase (p38 MAPK). The aim of the study was to investigate the effect of NF-κB and p38 MAPK in activated monocytes/macrophages on cytokines of rats with acute pancreastitis.

METHODS: Taurocholate (3% and 5%) at doses of 1 mL/kg was administered into the biliopancreatic duct of male Sprague-Dawley (SD) rats to reduce acute edematous pancreariris (AEP) and acute necrotizing pancreatitis (ANP). Pancreatic tissues were prepared immediately after death. At this point, blood was obtained for determination of serum amylase and pro-inflammatory TNF-α and IL-6. Activated monocytes/macrophages were captured from blood and so were ascites. NF-κB and p38 MAPK in activated monocytes/macrophages were measured by immunohistochemistry method. Pancreatic tissue samples were prepared for routine light microscopy, using hematoxylin and eosin (HE) staining.

RESULTS: The serum levels of amylase were 3056.00 ± 1232.35 IU/L and 4865.12 ± 890.34 IU/L at 3 and 6 h in ANP group, which were significantly higher than those (3056.00 ± 1232.35 IU/L and 3187.17 ± 821.16 IU/L) (P < 0.05, respectively) in AEP group. In ascites the levels were 3.32 ± 1.01 g and 3.76 ± 1.12 g at 3 and 6 h in ANP group, which were significantly higher than those (1.43 ± 1.02 g and 2.56 ± 1.21 g) (P < 0.05, respectively) in AEP group. The serum levels of TNF-α were 54.27 ± 23.48 pg/mL and 67.83 ± 22.02 pg/mL in AEP group and 64.28 ± 20.79 pg/mL and 106.59 ± 43.71 pg/mL in ANP group, and the serum levels of IL-6 were 428.12 ± 140.30 pg/mL and 420.13 ± 139.40 pg/mL in AEP group and 1600.32 ± 309.78 pg/mL and 2203.76 ± 640.85 pg/mL in ANP group, which were far significantly higher than those in sham group (P < 0.001, respectively). The serum level of TNF-α 6 h after establishment of the studied model and that of IL-6 at 3 and 6 h in ANP group were significantly higher than those in AEP (P < 0.05, P < 0.001, P < 0.05). In ANP group, the levels of serum TNF-α and IL-6 6 h after establishment of the studied model were significantly higher than those 3 h after establishment of studied model (P < 0.05, P < 0.05, respectively). Three and 6 h after establishment of the model, typical pathological changesof AEP and ANP were found, such as large numbers of inflammatory cells, edema, hemorrhage, necrosis, large amount of ascites. In AEP, NF-κB and p38 MAPK in activated monocytes/macrophages were moderately found at 3 and 6 h after introduction of the model. However, in ANP, the expression of NF-κB and p38 MAPK in activated monocytes/macrophages was upregulated evidently at 3 and 6 h after introduction of the model, reaching their highest levels at 6 h after introduction of the model, which were consistent with the levels of TNF-α and IL-6.

CONCLUSION: Cytokine TNF-α and IL-6 play a main role in acute pancreatitis, expression of NF-κB and p38 MAPK in activated monocytes/macrophages might play a major role in cytokine transcription and biosynthesis.

Elevated protein carbonyls as plasma markers of oxidative stress in acute pancreatitis

BACKGROUND

Experimental studies have demonstrated that protein and lipid oxidation is a feature of acute pancreatitis and that antioxidant pretreatment can ameliorate the severity of the disease. Justification for a clinical trial of antioxidant therapy requires stronger evidence for oxidative stress in patients.

AIMS

To determine if oxidative stress is evident in patients with acute pancreatitis on admission to hospital, if it increases after admission and if it is related to disease severity.

METHODS

Measurement of plasma concentrations of protein carbonyls and malondialdehyde as markers of protein oxidation and lipid peroxidation, respectively, in a consecutive series of 85 patients with acute pancreatitis 0, 2 and 5 days after admission.

RESULTS

Patients with acute pancreatitis had significantly increased concentrations of protein carbonyls in plasma on recruitment (median 27 h after the onset of symptoms) that persisted over 5 days. Protein carbonyls were higher in severe compared with mild disease (median 0.099 and 0.043 nmol/mg protein, respectively, p = 0.0016). They were higher at day 0 in patients recruited with more established pancreatitis than in those presenting early. No increases in malondialdehyde were seen. Receiver operator characteristic curve analysis demonstrated that protein carbonyls at day 0 were comparable with C-reactive protein at predicting pancreatitis severity.

CONCLUSION

Our demonstration of substantial protein oxidation provides further evidence for oxidative stress in patients with severe pancreatitis. Our results suggest that there could be a window for early antioxidant intervention and that protein carbonyls could be a useful plasma marker of oxidative injury.