The role of polymorphonuclear leukocytes and oxygen-derived free radicals in experimental acute pancreatitis: mediators of local destruction and activators of inflammation

Glucocorticoid Treatment in Acute Respiratory Distress Syndrome: An Overview on Mechanistic Insights and Clinical Benefit

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS), triggered by various pathogenic factors inside and outside the lungs, leads to diffuse lung injury and can result in respiratory failure and death, which are typical clinical critical emergencies. Severe acute pancreatitis (SAP), which has a poor clinical prognosis, is one of the most common diseases that induces ARDS. When SAP causes the body to produce a storm of inflammatory factors and even causes sepsis, clinicians will face a two-way choice between anti-inflammatory and anti-infection objectives while considering the damaged intestinal barrier and respiratory failure, which undoubtedly increases the difficulty of the diagnosis and treatment of SAP-ALI/ARDS. For a long time, many studies have been devoted to applying glucocorticoids (GCs) to control the inflammatory response and prevent and treat sepsis and ALI/ARDS. However, the specific mechanism is not precise, the clinical efficacy is uneven, and the corresponding side effects are endless. This review discusses the mechanism of action, current clinical application status, effectiveness assessment, and side effects of GCs in the treatment of ALI/ARDS (especially the subtype caused by SAP).

Betulinic Acid Ameliorates the Severity of Acute Pancreatitis via Inhibition of the NF-κB Signaling Pathway in Mice

Acute pancreatitis (AP) is an inflammatory disorder, involving acinar cell death and the release of inflammatory cytokines. Currently, there are limited effective therapeutic agents for AP. Betulinic acid (BA) is a pentacyclic triterpenoid extracted from Betula platyphylla that has been shown to have anti-inflammatory effects. In this study, we aimed to investigate the effects of BA on AP and elucidate the potential underlying mechanisms. AP was induced in mice through six intraperitoneal injections of cerulein. After the last cerulein injection, the mice were sacrificed. Our results revealed that pre- and post-treatment with BA significantly reduced the severity of pancreatitis, as evidenced by a decrease in histological damage in the pancreas and lung, serum amylase and lipase activity and pancreatic myeloperoxidase activity. Furthermore, BA pretreatment reduced proinflammatory cytokine production, augmentation of chemokines, and infiltration of macrophages and neutrophils in the pancreas of AP mice. In addition, mice that were pretreated with BA showed a reduction in Iκ-Bα degradation and nuclear factor-kappa B (NF-κB) binding activity in the pancreas. Moreover, BA reduced the production of proinflammatory cytokines and NF-κB activation in pancreatic acinar cells (PACs). These findings suggest that BA may have prophylactic and therapeutic effects on AP via inhibition of the NF-κB signaling pathway.

Severe Acute Pancreatitis in Autopsies Associated With Surgeries and Severe Inflammatory Diseases

OBJECTIVE

We clarified clinicopathological characteristics of acute pancreatitis in terminal patients.

METHODS

Pathological changes in the entire pancreas from serial autopsies (N = 183) classified lesions into the following 3 categories: focal neutrophil infiltration, focal necrotizing pancreatitis, and diffuse necrotizing pancreatitis. The former two are possible precursors of diffuse necrotizing pancreatitis. Immunohistochemical staining was performed to analyze pancreatic stellate cells and inflammatory cells.

RESULTS

There were pathologically acute pancreatitis in 45 patients (24.6%), and no patients were diagnosed with it before autopsy. Focal neutrophil infiltration was present in 22 cases, focal necrotizing pancreatitis in 18 cases, and diffuse necrotizing pancreatitis in 5 cases. Severe inflammatory disease and surgery were associated with acute pancreatitis. Sepsis due to viral or bacterial infection was the most common cause of acute pancreatitis. Patients with diffuse necrotizing pancreatitis showed low white blood cell counts, while amylase levels were not increased. Increase in α-smooth muscle actin and nestin-positive stellate cell numbers in acute pancreatitis was correlated to increase in numbers of CD34-positive vascular endothelium, CD68- or CD163-positive macrophages, CD138-positive plasmacytes, CD3-positive T lymphocytes, and myeloperoxidase-positive leucocytes.

CONCLUSIONS

Necrotizing pancreatitis without typical clinical signs was frequently detected in autopsy samples. Clinicians must be mindful of necrotizing pancreatitis in terminal patients.

Extracellular release of ATP promotes systemic inflammation during acute pancreatitis

In the current study, we explored the role of extracellular ATP (eATP) in promoting systemic inflammation during development of acute pancreatitis (AP). Release of extracellular (e)ATP was evaluated in plasma and bronchoalveolar lavage fluid (BALF) of mice with experimental acute pancreatitis (AP). Prophylactic intervention using apyrase or suramin was used to understand the role and contribution of eATP in pancreatitis-associated systemic injury. AP of varying severity was induced in C57BL/6 mice using 1-day or 2-day caerulein, caerulein + LPS and l-arginine models. eATP was measured in plasma and BALF. Mice were treated with suramin or apyrase in the caerulein and l-arginine models of AP. Plasma cytokines, lung, and pancreatic myeloperoxidase, and morphometric analysis of pancreatic and lung histology, were used to assess the severity of pancreatitis. Plasma eATP and purinergic 2 (P2) receptors in the pancreas and lungs were significantly elevated in the experimental models of AP. Blocking the effect of eATP by suramin led to reduced levels of plasma IL-6 and TNFα as well as reduced lung, and pancreatic injury. Neutralizing eATP with apyrase reduced systemic injury but did not ameliorate local injury. The results of this study support the role of eATP and P2 receptors in promoting systemic inflammation during AP. Modulating purinergic signaling during AP can be an important therapeutic strategy in controlling systemic inflammation and, thus, systemic inflammatory response syndrome during AP.NEW & NOTEWORTHY Released ATP from injured cells promotes systemic inflammation in acute pancreatitis.

Calycosin alleviates cerulein-induced acute pancreatitis by inhibiting the inflammatory response and oxidative stress via the p38 MAPK and NF-κB signal pathways in mice

Acute pancreatitis (AP) is a common acute abdominal disease accompanied by systemic inflammatory response syndrome, and could even be complicated by multiple-organ damage. This study aimed to examine whether calycosin, an isoflavone isolated from Radix astragali with antioxidant and anti-inflammatory activity, could protect against AP induced by cerulein. To this end, Balb/C mice were injected with cerulein (50 μg/kg) to establish the animal model of AP. Calycosin (25 and 50 mg/kg, p.o.) was administered 1 h prior to the first cerulein injection. After the last injection of cerulein, the mice were sacrificed and blood was obtained for cytokine analysis. The pancreas was removed for morphological examination, myeloperoxidase (MPO) and malondialdehyde (MDA) analyses, immunohistochemistry, and western blot analysis. Calycosin treatment reversed the increased serum levels of amylase and lipase, alleviated the pathological damage in the pancreas, and decreased the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β in mice with AP. Additionally, calycosin significantly reduced cerulein-induced pancreatic edema, inhibited MPO activity and increased superoxide dismutase (SOD) activity, and inhibited the expression of NF-κB/p65 and phosphorylation of the inhibitor of NF-κB (IκBα) and p38 MAPK. These results suggested that calycosin protects against AP by exerting anti-inflammatory and anti-oxidative stress effects via the p38 MAPK and NF-κB signal pathways. Calycosin's benefits for AP patients need to be explored further.

Methane-rich saline alleviates cerulein-induced acute pancreatitis by inhibiting inflammatory response, oxidative stress and pancreatic apoptosis in mice

BACKGROUND

Acute pancreatitis (AP) is a potentially life-threatening gastrointestinal disease involving intracellular activation of digestive enzymes and pancreatic acinar cell injury. The present study was performed to investigate whether methane-rich saline (MS) was involved in the regulation of AP.

METHODS

MS (16ml/kg) was administered at different dosing frequencies on mice with cerulein-induced AP. Serum amylase, lipase and histopathological changes in the pancreas tissue were measured. Serum cytokine TNFα, IL-6, IFNγ and IL-10 were detected by ELISA. The mRNA levels of these inflammatory cytokines in the pancreas were detected by real time-PCR. Myeloperoxidase (MPO) and superoxide dismutase (SOD) were determined using commercial kits. Apoptosis was assessed by immunohistochemistry and Western blot.

RESULTS

MS treatment reversed the increased serum level of amylase and lipase, alleviated the pathological damage in the pancreas, and decreased the expression of TNFα, IL-6, IFNγ and IL-10 in cerulean-induced AP mice. In addition, MPO was down-regulated and SOD was up-regulated in the MS treated pancreas, indicating that MS had an anti-oxidant effect against AP. Furthermore, MS protected pancreatic cells against cerulean-induced apoptosis and abolished cleaved caspase-3.

CONCLUSION

MS exerted anti-inflammatory, anti-oxidant and anti-apoptotic effects on cerulein-induced AP in mice and may proved to be a promising therapeutic agent for the clinical treatment of pancreatitis.

Antioxidant Effect of Ukrain Versus N-Acetylcysteine Against Acute Biliary Pancreatitis in An Experimental Rat Model

Purpose/Aim: Oxidative stress plays an important role in the pathogenesis of acute pancreatitis (AP). We compared the therapeutic effects of Ukrain (NSC 631570) and N-acetylcysteine (NAC) in rats with AP.

MATERIALS AND METHODS

Forty male Sprague Dawley rats were divided into four groups: controls; AP; AP with NAC; and AP with Ukrain. AP was induced via the ligation of the bile-pancreatic duct; drugs were administered intraperitoneally (i.p.) 30 min and 12 h after AP induction. Twenty-four hours after AP induction, animals were sacrificed and the pancreas was excised. Levels of malondialdehyde (MDA) and nitric oxide (NO), and activity levels of tumor necrosis factor (TNF)-α, and myeloperoxidase (MPO) were measured in tissue samples. Total oxidant status (TOS), total antioxidant status (TAS), and total bilirubin, as well as activity levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), amylase and lipase were measured in serum samples. Pancreatic tissue histopathology was also evaluated.

RESULTS

Test drugs reduced levels of MDA, NO, TNF-α, total bilirubin, AST, ALT, TOS and MPO, amylase and lipase activities (P < 0.001), and increased TAS (P < 0.001). Rats treated with test drugs attenuated AP-induced morphologic changes and decreased pancreatic damage scores compared with the AP group (P < 0.05). Both test drugs attenuated pancreatic damage, but the therapeutic effect was more pronounced in rats that received Ukrain than in those receiving NAC.

CONCLUSIONS

These results suggest that treatment with Ukrain or NAC can reduce pancreatic damage via anti-inflammatory and antioxidant effects.

Therapeutic implications of innate immune system in acute pancreatitis

INTRODUCTION

Acute pancreatitis (AP) is an inflammatory disorder of the pancreas encompassing a cascade of cellular and molecular events. It starts from premature activation of zymogens with the involvement of innate immune system to a potential systemic inflammatory response and multiple organ failure. Leukocytes are the major cell population that participate in the propagation of the disease. Current understanding of the course of AP is still far from complete, limiting treatment options mostly to conservative supportive care. Emerging evidence has pointed to modulation of the immune system for strategic therapeutic development, by mitigating the inflammatory response and severity of AP. In the current review, we have focused on the role of innate immunity in the condition and highlighted therapeutics targeting it for treatment of this challenging disease.

AREAS COVERED

The current review has aimed to elaborate in-depth understanding of specific roles of innate immune cells, derived mediators and inflammatory pathways that are involved in AP. Summarizing the recent therapeutics and approaches applied experimentally that target immune responses to attenuate AP.

EXPERT OPINION

The current state of knowledge on AP, limitations of presently available therapeutic approaches and the promise of therapeutic implications of innate immune system in AP are discussed.

Hydrogen-rich saline protects against ischemia/reperfusion injury in grafts after pancreas transplantations by reducing oxidative stress in rats

Purpose. This study aimed to investigate the therapeutic potential of hydrogen-rich saline on pancreatic ischemia/reperfusion (I/R) injury in rats. Methods. Eighty heterotopic pancreas transplantations (HPT) were performed in syngenic rats. The receptors were randomized blindly into the following three groups: the HPT group and two groups that underwent transplantation and administration of hydrogen-rich saline (HS, >0.6 mM, 6 mL/kg) or normal saline (NS, 6 mL/kg) via the tail vein at the beginning of reperfusion (HPT + HS group, HPT + NS group). Samples from the pancreas and blood were taken at 12 hours after reperfusion. The protective effects of hydrogen-rich saline against I/R injury were evaluated by determining the changes in histopathology and measuring serological parameters, oxidative stress-associated molecules, and proinflammatory cytokines. Results. Administration of hydrogen-rich saline produced notable protection against pancreatic I/R injury in rats. Histopathological improvements and recovery of impaired pancreatic function were observed. In addition, TNF-α, IL-1β, and IL-6 were reduced markedly in the HPT + HS group. Additionally, there were noticeable inhibitory effects on the pancreatic malondialdehyde level and considerable recruitment of SOD and GPx, which are antioxidants. Conclusion. Hydrogen-rich saline treatment significantly attenuated the severity of pancreatic I/R injury in rats, possibly by reducing oxidative stress and inflammation.

Hydrogen-rich saline inhibits NLRP3 inflammasome activation and attenuates experimental acute pancreatitis in mice

Increasing evidence has demonstrated that reactive oxygen species (ROS) induces oxidative stress and plays a crucial role in the pathogenesis of acute pancreatitis (AP). Hydrogen-rich saline (HRS), a well-known ROS scavenger, has been shown to possess therapeutic benefit on AP in many animal experiments. Recent findings have indicated that the NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome, an intracellular multiprotein complex required for the maturation of interleukin- (IL-) 1β, may probably be a potential target of HRS in the treatment of AP. Therefore, in this study, we evaluated the activation of NLRP3 inflammasome and meanwhile assessed the degree of oxidative stress and inflammatory cascades, as well as the histological alterations in mice suffering from cerulein-induced AP after the treatment of HRS. The results showed that the activation of NLRP3 inflammasome in AP mice was substantially inhibited following the administration of HRS, which was paralleled with the decreased NF-κB activity and cytokines production, attenuated oxidative stress and the amelioration of pancreatic tissue damage. In conclusion, our study has, for the first time, revealed that inhibition of the activation of NLRP3 inflammasome probably contributed to the therapeutic potential of HRS in AP.

Clinicobiochemical investigations of gangrenous mastitis in does: immunological responses and oxidative stress biomarkers

A total of 50 does were used to determine selected hematological and biochemical parameters with special references to oxidative stress markers, acute phase protein profiles, and proinflammatory cytokines in healthy and gangrenous mastitis affected does. Animals were divided into two equal groups represented as clinically healthy (control) and diseased groups, respectively. The bacteriological examination of milk samples from diseased does revealed many types of bacterial infection. The isolated bacteria were Staphylococcus aureus (N=23/25), Escherichia coli (N=11/25), and Clostridium perfringens (N=4/25). There was a significant increase in the levels of β-hydroxybutyrate, non-esterified free fatty acids, triglyceride, low density lipoprotein cholesterol (LDL-C), aspartate aminotransferase, and alanine aminotransferase and a significant reduction in the levels of glucose, cholesterol, and high density lipoprotein cholesterol (HDL-C) in does with gangrenous mastitis compared to healthy does. Moreover, there was a significant increase in the levels of malondialdehyde and uric acid with a significant decrease in the levels of reduced glutathione, super oxide dismutase, and catalase in does with gangrenous mastitis compared to healthy does. In addition, there was a significant increase in the haptoglobin, serum amyloid A, fibrinogen, interleukin 6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) in does with gangrenous mastitis compared to healthy ones. Conclusively, oxidative stress biomarkers, acute phase proteins, and proinflammatory cytokines play an essential task as biomarkers for gangrenous mastitis in does. Mastitis may be considered as one of the ketotic stressors in does after parturition.

Lasting inhibition of receptor-mediated calcium oscillations in pancreatic acini by neutrophil respiratory burst--a novel mechanism for secretory blockade in acute pancreatitis?

Although overwhelming evidence indicates that neutrophil infiltration is an early event in acute pancreatitis, the effect of neutrophil respiratory burst on pancreatic acini has not been investigated. In the present work, effect of fMLP-induced neutrophil respiratory burst on pancreatic acini was examined. It was found that neutrophil respiratory burst blocked calcium oscillations induced by cholecystokinin or by acetylcholine. Such lasting inhibition was dependent on the density of bursting neutrophils and could be overcome by increased agonist concentration. Inhibition of cholecystokinin stimulation was also observed in AR4-2J cells. In sharp contrast, neutrophil respiratory burst had no effect on calcium oscillations induced by phenylephrine (PE), vasopressin, or by ATP in rat hepatocytes. These data together suggest that inhibition of receptor-mediated calcium oscillations in pancreatic acini by neutrophil respiratory burst would lead to secretory blockade, which is a hallmark of acute pancreatitis. The present work has important implications for clinical treatment and management of acute pancreatitis.

Effects of curcumin on proinflammatory cytokines and tissue injury in the early and late phases of experimental acute pancreatitis

BACKGROUND & AIMS

Acute pancreatitis (AP) varies from mild to severe necrotizing changes with high mortality. The objective of the current study was to investigate the effects of curcumin on tissue injury and proinflammatory cytokines in the early and late phases of AP.

METHODS

AP was induced by sodium taurocholate in rats (n = 140). First group was left untreated. Group II received 100 mg/kg curcumin daily starting 20 days before AP induction. The rats were allocated into 7 sub-groups (n:5) and were sacrificed at 2, 6, 12, 24, 72, 144 and 288 h following the induction of AP. Blood and pancreatic tissue samples were collected for biochemical and histopathologic evaluations and the assessment of protein and mRNA levels, as well.

RESULTS

Curcumin decreased total histopathologic scores in comparison with those of the taurocholate group (P < 0.05). Curcumin increased Caspase-3 activity and decreased trypsin activity, while inhibited nuclear factor-κ (NF-κB) at all time points (P < 0.05) and moreover reduced activator protein-1 (AP-1). Curcumin decreased chemokine (except for 288 h), TNF-α (except for 2 and 24 h), IL-6 (except for 2, 6 and 288 h) and iNOS (except for 144 and 288 h) mRNA levels (P < 0.05). Curcumin serum nitric oxide (NO) (except for 144 and 288 h) levels were reduced, as well.

CONCLUSIONS

In conclusion, curcumin reduced tissue injury, trypsin activation and inhibited NF-κB and AP-1. However TNF-α, IL-6 and iNOS and NO were not inhibited at all time points. Therefore no direct correlation was detected in the subgroups between tissue injury, proinflammatory cytokines and oxidative enzymes.

Understanding resolvin signaling pathways to improve oral health

The discovery of resolvins has been a major breakthrough for understanding the processes involved in resolution of inflammation. Resolvins belong to a family of novel lipid mediators that possess dual anti-inflammatory and pro-resolution actions. Specifically, they protect healthy tissue during immune-inflammatory responses to infection or injury, thereby aiding inflammation resolution and promoting tissue healing. One of the major concerns in modern medicine is the management and treatment of oral diseases, as they are related to systemic outcomes impacting the quality of life of many patients. This review summarizes known signaling pathways utilized by resolvins to regulate inflammatory responses associated with the oral cavity.

Hydrogen-rich saline reduces the oxidative stress and relieves the severity of trauma-induced acute pancreatitis in rats

BACKGROUND

Currently, little evidence exists to support whether the therapeutic approaches for treating ordinary acute pancreatitis (AP) are effective in trauma-induced pancreatitis. Hydrogen-rich (H2) saline is an antioxidant treatment capable of ameliorating the severity of L-arginine-induced AP. In this study, we attempted to validate its protective role against traumatic pancreatitis (TP).

METHODS

A previously established experimental rat model of TP was generated by controlled delivery of high pressure air impact. The protective effects of H2 saline against TP were evaluated in this model system by measuring survival rate and determining changes in histopathology, plasma enzymes, cytokines, and oxidative stress-associated molecules.

RESULTS

Intraperitoneal administration of H2-rich saline produced a pronounced protection against TP in rats. Significant improvements were observed in survival rate and histopathological findings. In addition, plasma cytokines concentrations were reduced in H2 saline-treated TP rats. Although no marked inhibitory effect on plasma amylase and lipase activities was observed, H2 saline caused considerable suppression of pancreatic malondialdehyde level and recruitment of endogenous pancreatic antioxidants, such as glutathione and superoxide dismutase.

CONCLUSIONS

H2-rich saline has beneficial effects on TP, presumably because of its detoxification activities against excessive reactive oxygen species. Our findings highlight the potential of H2-rich saline as a therapeutic agent of trauma-induced AP.

Dexamethasone down-regulates the inflammatory mediators but fails to reduce the tissue injury in the lung of acute pancreatitis rat models

Pulmonary complications are frequent in the course of acute pancreatitis. We investigate the effects of dexamethasone on lung injury in mild and severe AP. Mild and severe acute pancreatitis was induced in rats by bile-pancreatic duct obstruction and infusion of 3.5% sodium taurocholate into the bile-pancreatic duct, respectively. Dexamethasone (1 mg/kg) was given by intramuscular injection 1 h after acute pancreatitis. Plasma amylase activity was measured to evaluate the pancreas damage. Lungs were harvested for analysing mRNA expression of monocyte chemoattractant protein-1 (MCP-1), cytokine-induced neutrophil chemoattractant (CINC), P-selectin and intercellular adhesion molecule-1 (ICAM-1), myeloperoxidase (MPO) activity (as index of neutrophil infiltration) and histological examination. Dexamethasone reduced the hyperamylasemia and hindered the pulmonary upregulation of MCP-1, CINC, P-selectin and ICAM-1, in both mild and severe acute pancreatitis. Despite this, dexamethasone treatment failed to reduce MPO activity and histological alterations developed in lungs during acute pancreatitis, either in bile-pancreatic duct obstruction or sodium taurocholate model. We conclude that pulmonary local factors different from inflammatory mediators contribute to leukocyte recruitment, so that although dexamethasone down-regulated the lung expression of chemokines and adhesion molecules during acute pancreatitis it was not able to prevent leukocyte infiltration, which could be responsible for maintaining the lung injury in either mild or severe acute pancreatitis.

Evaluation of N-acetylcysteine treatment in acute pancreatitis-induced lung injury

OBJECTIVE

Pulmonary complications are frequent during acute pancreatitis (AP). We investigate the effects of N-acetylcysteine (NAC) on lung injury in mild and severe AP. ANIMALS AND TREATMENT: Mild and severe AP was induced in rats by bile-pancreatic duct obstruction (BPDO) and infusion of 3.5 % sodium taurocholate (NaTc) into the bile-pancreatic duct, respectively. NAC (50 mg/kg) was given 1 h before and 1 h after AP.

METHODS

Amylase activity was measured in plasma. Lungs were harvested for mRNA expression analysis of monocyte chemoattractant protein-1 (MCP-1), cytokine-induced neutrophil chemoattractant (CINC), P-selectin and intercellular adhesion molecule-1 (ICAM-1), myeloperoxidase (MPO) activity and histological examination.

RESULTS

Hyperamylasemia was reduced by NAC in both AP models. NAC down-regulated MCP-1, CINC and P-selectin in BPDO- but not in NaTc-induced AP. Pulmonary insults did not vary in mild AP and were exacerbated in severe AP by NAC treatment. NAC reduced lung MPO activity in mild but not in severe AP.

CONCLUSIONS

Although NAC treatment down-regulated inflammatory mediators in lungs during AP it did not prevent leukocyte infiltration, which could be responsible for maintaining the lung injury. As a result, NAC aggravated the lung damage in severe AP and failed to exert beneficial effects in the mild disease model.

P-selectin mediates neutrophil rolling and recruitment in acute pancreatitis

BACKGROUND

The adhesive mechanisms regulating leucocyte-endothelium interactions in the pancreas remain elusive, but selectins may play a role. This study examined the molecular mechanisms mediating leucocyte rolling along the endothelium in the pancreas and the therapeutic potential of targeting the rolling adhesive interaction in acute pancreatitis (AP).

METHODS

Pancreatitis was induced by retrograde infusion of 5 per cent sodium taurocholate into the pancreatic duct, repeated intraperitoneal administration of caerulein (50 µg/kg) or intraperitoneal administration of L-arginine (4 g/kg) in C57BL/6 mice. A control and a monoclonal antibody against P-selectin were administered before and after induction of AP. Serum and tissue were sampled to assess the severity of pancreatitis, and intravital microscopy was used to study leucocyte rolling.

RESULTS

Taurocholate infusion into the pancreatic duct increased the serum level of trypsinogen, trypsinogen activation, pancreatic neutrophil infiltration, macrophage inflammatory protein (MIP) 2 formation and tissue damage. Immunoneutralization of P-selectin decreased the taurocholate-induced increase in serum trypsinogen (median (range) 17·35 (12·20-30·00) versus 1·55 (0·60-15·70) µg/l; P = 0·017), neutrophil accumulation (4·00 (0·75-4·00) versus 0·63 (0-3·25); P = 0·002) and tissue damage, but had no effect on MIP-2 production (14·08 (1·68-33·38) versus 3·70 (0·55-51·80) pg/mg; P = 0·195) or serum trypsinogen activating peptide level (1·10 (0·60-1·60) versus 0·45 (0-1·80) µg/l; P = 0·069). Intravital fluorescence microscopy revealed that anti-P-selectin antibody inhibited leucocyte rolling completely in postcapillary venules of the inflamed pancreas.

CONCLUSION

Inhibition of P-selectin protected against pancreatic tissue injury in experimental pancreatitis. Targeting P-selectin may be an effective strategy to ameliorate inflammation in AP.

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.

Targeting P-selectin in acute pancreatitis

IMPORTANCE OF THE FIELD

Acute pancreatitis (AP) is a multifactorial disorder not fully understood yet. In particular, the pathogenetic pathways promoting a severe life-threatening course of AP are the subject of ongoing investigations. P-selectin has been shown to play a central role in the complex pathophysiology in AP as well as various other inflammatory conditions.

AREAS COVERED IN THIS REVIEW

P-selectin function in AP is reviewed with focus on its dual function as a mediator of leukocyte recruitment and cell adhesion, which implies the unique effect of linking both inflammation and coagulation, especially in the progression from mild to severe necrotizing AP. Potential therapeutic aspects are discussed with regard to the clinical situation.

WHAT THE READER WILL GAIN

A better understanding of the pathogenic role of P-selectin in AP and of the rationale for a therapeutic blockade.

TAKE HOME MESSAGE

P-selectin is a glycoprotein that mediates the adhesion of activated platelets and leukocytes to the vessel wall in various inflammatory conditions. Both pathophysiological steps are closely linked and play a key role in the course of severe AP. A treatment approach by inhibition of P-selectin could be of distinct interest as a therapeutic option in severe AP.

Effects of dexamethasone on intercellular adhesion molecule 1 expression and inflammatory response in necrotizing acute pancreatitis in rats

OBJECTIVES

Adhesion molecules are involved in the inflammatory response during acute pancreatitis (AP). We investigated the effect of dexamethasone (Dx) on intercellular adhesion molecule 1 (ICAM-1) expression during AP and its consequences on leukocyte recruitment and pancreatic damage.

METHODS

Acute pancreatitis was induced in rats by 3.5% sodium taurocholate for 3 hours and 6 hours. Dexamethasone (1 mg/kg) was administered either 30 minutes before or 1 hour after inducing AP. Messenger RNA ICAM-1 expression in pancreas and lung, membrane-bound ICAM-1 in acinar cells, and ICAM-1 plasma levels were analyzed. Histological examination of the pancreas and neutrophil infiltration in pancreas and lung were also measured.

RESULTS

Prophylactic and therapeutic administration of Dx down-regulated ICAM-1 expression in pancreas and lung from early AP. Dexamethasone given before AP reduced the pancreatic damage, but lung inflammation was not prevented. Therapeutic Dx treatment was ineffective in avoiding leukocyte recruitment into the pancreas and lung in rats with AP. High ICAM-1 concentration was found in plasma during AP, which was not reduced by Dx treatments.

CONCLUSIONS

Dexamethasone down-regulates ICAM-1 expression, but it does not completely prevent leukocyte recruitment during sodium taurocholate-induced AP.

Effect of pentoxifylline and/or alpha lipoic acid on experimentally induced acute pancreatitis

Acute pancreatitis is a sudden inflammation of the pancreas that may be life threatening disease with high mortality rates; particularly in presence of systemic inflammatory response and multiple organ failure despite of the conventional antibiotic and symptomatic treatment. Oxidative stress has been shown to be involved in the pathophysiology of acute pancreatitis. This study was designed to investigate the possible effect of pentoxifylline and alpha lipoic acid respectively and in combination on rats with L-arginine induced acute pancreatitis. Rats were divided as follow; Group 1: served as control, Group 2 and Group 3: sacrificed after 24h and 7 days; respectively, from induction of acute pancreatitis by L-arginine 250 mg/100g, Group 4 and Group 5: rats treated by pentoxifylline (12 mg/kg) and sacrificed after 24h and 7 days; respectively, from induction of acute pancreatitis, Group 6 and Group 7: treated by alpha lipoic acid (1mg/kg) and sacrificed after 24h and 7 days; respectively, from induction of acute pancreatitis, Group 8 and Group 9: treated by pentoxifylline and alpha lipoic acid and sacrificed after 24h and 7 days; respectively, from induction of acute pancreatitis. Serum samples were collected to assay levels of amylase enzyme, C-reactive protein, IL-6, catalase enzyme activity, malondialdehyde and pancreases were excised for histopathological examination and assay of pancreatic myeloperoxidase. L-arginine induced-acute pancreatitis was evident by increased in serum marker enzymes and by histopathological findings compared to control group. Pentoxifylline and alpha lipoic acid respectively provided protection against L-arginine induced acute pancreatitis possibly by their antioxidant and anti-inflammatory effect. Treatment with alpha lipoic acid exhibited pronounced improvement in the course of pancreatitis when compared to treatment with pentoxifylline. Moreover, the combination of pentoxifylline and alpha lipoic acid offered the most evident protection when compared to groups that received monotherapy; pointing to the effectiveness of such combination therapy.

N-acetylcysteine in acute pancreatitis

Premature trypsinogen activation and production of oxygen free radicals (OFR) are early pathogenic events which occur within acinar cells and trigger acute pancreatitis (AP). OFR exert their harmful effects on various cell components causing lipid peroxidation, disturbances in calcium homeostasis and DNA damage, which lead to increased cell injury and eventually cell death. This review presents the most recent data concerning the effects of N-Acetylcysteine (NAC), in the treatment of AP. NAC is an antioxidant capable of restoring the levels of Glutathione, the most important cellular antioxidant. Studies show the beneficial effects of NAC treatment in preventing OFR production and therefore attenuating oxidative damage. Additionally, NAC treatment has been shown to prevent the increase in cytosolic Ca²⁺ concentration and reduce the accumulation of enzymes in acinar cells during AP. The prevention, by NAC, of these pathological events occurring within acinar would contribute to reducing the severity of AP. NAC is also capable of reducing the activation of transcription factors especially sensitive to the cellular redox state, such as Nuclear factor-κB, signal transducer and activator of transcription-3 and mitogen-activated protein kinase. This leads to a down-regulation of cytokines, adhesion molecules and chemokine expression in various cell types during AP. These findings point to NAC as a powerful therapeutic treatment, attenuating oxidative-stress-induced cell injury and other pathological events at early stages of AP, and potentially contributing to reducion in the severity of disease.

Experimental evidence of obesity as a risk factor for severe acute pancreatitis

The incidence of acute pancreatitis, an inflammation of the pancreas, is increasing worldwide. Pancreatic injury is mild in 80%-90% of patients who recover without complications. The remaining patients may develop a severe disease with local complications such as acinar cell necrosis, abscess and remote organ injury including lung injury. The early prediction of the severity of the disease is an important goal for physicians in management of patients with acute pancreatitis in order to optimize the therapy and to prevent organ dysfunction and local complications. For that purpose, multiple clinical scale scores have been applied to patients with acute pancreatitis. Recently, a new problem has emerged: the increased severity of the disease in obese patients. However, the mechanisms by which obesity increases the severity of acute pancreatitis are unclear. Several hypotheses have been suggested: (1) obese patients have an increased inflammation within the pancreas; (2) obese patients have an increased accumulation of fat within and around the pancreas where necrosis is often located; (3) increase in both peri- and intra-pancreatic fat and inflammatory cells explain the high incidence of pancreatic inflammation and necrosis in obese patients; (4) hepatic dysfunction associated with obesity might enhance the systemic inflammatory response by altering the detoxification of inflammatory mediators; and (5) ventilation/perfusion mismatch leading to hypoxia associated with a low pancreatic flow might reduce the pancreatic oxygenation and further enhance pancreatic injury. Recent experimental investigations also show an increased mortality and morbidity in obese rodents with acute pancreatitis and the implication of the adipokines leptin and adiponectin. Such models are important to investigate whether the inflammatory response of the disease is enhanced by obesity. It is exciting to speculate that manipulation of the adipokine milieu has the potential to influence the severity of acute pancreatitis.

Mechanisms of dexamethasone-mediated chemokine down-regulation in mild and severe acute pancreatitis

This study aimed to investigate the role of therapeutic dexamethasone (Dex) treatment on the mechanisms underlying chemokine expression during mild and severe acute pancreatitis (AP) experimentally induced in rats. Regardless of the AP severity, Dex (1 mg/kg), administered 1 h after AP, reduced the acinar cell activation of extracellular signal-regulated kinase (ERK) and c-Jun-NH(2)-terminal kinase (JNK) but failed to reduce p38-mitogen-activated protein kinase (MAPK) in severe AP. In both AP models, Dex inhibited the activation of nuclear factor-kappaB (NF-kappaB) and signal transducers and activators of transcription (STAT) factors. All of this resulted in pancreatic down-regulation of the chemokines monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant (CINC). Lower plasma chemokine levels as well as decreased amylasemia, hematocrit and plasma interleukin-1beta (Il-1beta) levels were found either in mild or severe AP treated with Dex. Pancreatic neutrophil infiltration was attenuated by Dex in mild but not in severe AP. In conclusion, by targeting MAPKs, NF-kappaB and STAT3 pathways, Dex treatment down-regulated the chemokine expression in different cell sources during mild and severe AP, resulting in decreased severity of the disease.

The role of redox status on chemokine expression in acute pancreatitis

This study focused on the involvement of oxidative stress in the mechanisms mediating chemokine production in different cell sources during mild and severe acute pancreatitis (AP) induced by bile-pancreatic duct obstruction (BPDO) and 3.5% NaTc, respectively. N-Acetylcysteine (NAC) was used as antioxidant treatment. Pancreatic glutathione depletion, acinar overexpression of monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant (CINC), and activation of p38MAPK, NF-kappaB and STAT3 were found in both AP models. NAC reduced the depletion of glutathione in BPDO- but not in NaTc-induced AP, in which oxidative stress overwhelmed the antioxidant capability of NAC. As a result, inhibition of the acinar chemokine expression and signalling pathways occurs in mild, but not in severe AP. However, MCP-1 and CINC expressions in whole pancreas and plasma chemokine levels were not reduced by NAC, even in BPDO-induced AP, suggesting that in addition to acini, other pancreatic cells produced chemokines by antioxidant resistant mechanisms. The high Il-6 plasma levels found during AP, both in NAC-treated and non-treated rats, pointed out cytokines as activating factors of chemokine expression in non-acinar cells. In conclusion, from early AP oxidant-mediated MAPK, NF-kappaB and STAT3 activation triggers the chemokine expression in acini but not in non-acinar cells.

Serum paraoxonase undergoes inhibition and proteolysis during experimental acute pancreatitis

Oxidative stress has a primary role in the pathogenesis of severe acute pancreatitis. Then, the antioxidant capacity is a critical factor in the progression of this disease. Serum paraoxonase-1 (PON1) is an esterase associated with high-density lipoprotein, which clinical interest resides in its ability to prevent or limit the lipid oxidation. The aim of this study was to investigate changes in PON1 activity in the early stages of acute pancreatitis and to find out if its alteration is related with the severity of the disease. To this purpose, we used an experimental model of taurocholate-induced mild and severe acute pancreatitis. Our results showed that serum activity and PON1 concentration decreased 18 h after the induction of a severe acute pancreatitis. In vitro analysis revealed that incubation with oxidized lipids obtained from pancreatitis samples results in the inactivation of the enzyme in a concentration-dependent manner. In addition to oxidative inactivation, we observed by Western blot, an immunoreactive band suggestive of proteolytic degradation of the enzyme, altogether indicating that during severe acute pancreatitis, there is a significant decrease in serum PON1 activity. This decrease is related with inactivation of the enzyme by oxidized lipids, probably followed by proteolytic degradation of the enzyme.

Acute pancreatitis

Acute pancreatitis is an inflammatory disease of the pancreas. Acute abdominal pain is the most common symptom, and increased concentrations of serum amylase and lipase confirm the diagnosis. Pancreatic injury is mild in 80% of patients, who recover without complications. The remaining patients have a severe disease with local and systemic complications. Gallstone migration into the common bile duct and alcohol abuse are the most frequent causes of pancreatitis in adults. About 15-25% of pancreatitis episodes are of unknown origin. Treatment of mild disease is supportive, but severe episodes need management by a multidisciplinary team including gastroenterologists, interventional radiologists, intensivists, and surgeons. Improved understanding of pathophysiology and better assessments of disease severity should ameliorate the management and outcome of this complex disease.

The role of inflammatory and parenchymal cells in acute pancreatitis

The infiltration of inflammatory cells into the pancreas is an early and central event in acute pancreatitis that promotes local injury and systemic complications of the disease. Recent research has yielded the important finding that resident cells of the pancreas (particularly acinar and pancreatic stellate cells) play a dynamic role in leukocyte attraction via secretion of chemokines and cytokines and expression of adhesion molecules. Significant progress has been made in recent years in our understanding of the role of leukocyte movement (adhesion to the blood vessel wall, transmigration through the blood vessel wall and infiltration into the parenchyma) in the pathophysiology of acute pancreatitis. This review discusses recent studies and describes the current state of knowledge in the field. It is clear that detailed elucidation of the numerous processes in the inflammatory cascade is an essential step towards the development of improved therapeutic strategies in acute pancreatitis. Studies to date suggest that combination therapy targeting different steps of the inflammatory cascade may be the treatment of choice for this disease.

Extrapancreatic organ impairment during acute pancreatitis induced by bile-pancreatic duct obstruction. Effect of N-acetylcysteine

Multiple organ failure is frequently associated with acute pancreatitis (AP). Our aim was to study pulmonary, hepatic and renal complications developed in the course of AP experimentally induced in rats by bile-pancreatic duct obstruction (BPDO), differentiating the complications caused by AP itself, from those directly caused by bile duct obstruction (BDO), after ligating the choledocus. N-acetylcysteine (NAC) was administered as a therapeutic approach. Myeloperoxidase activity revealed neutrophil infiltration in lungs from 12 h after BDO, even if AP was not triggered. Lactate dehydrogenase (LDH) activity indicated hepatocyte death from 48 h after BDO, and from 24 h following BPDO-induced AP onwards, an effect delayed until 48 h by NAC treatment. Rats with single cholestasis (BDO) and rats with BPDO-induced AP showed a significant increase in plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT) and bilirubin concentration from 12 h onwards, whose values were reduced by NAC treatment at early BPDO. No renal failure was found during 120 h of bile-pancreatic obstruction. Our results showed lung and liver impairment as a result of BDO, even if AP does not develop. Pancreatic damage and extrapancreatic complications during AP induced by BPDO were palliated by NAC treatment.

Severe acute pancreatitis: Clinical course and management

Severe acute pancreatitis (SAP) develops in about 25% of patients with acute pancreatitis (AP). Severity of AP is linked to the presence of systemic organ dysfunctions and/or necrotizing pancreatitis pathomorphologically. Risk factors determining independently the outcome of SAP are early multi-organ failure, infection of necrosis and extended necrosis (>50%). Up to one third of patients with necrotizing pancreatitis develop in the late course infection of necroses. Morbidity of SAP is biphasic, in the first week strongly related to early and persistence of organ or multi-organ dysfunction. Clinical sepsis caused by infected necrosis leading to multi-organ failure syndrome (MOFS) occurs in the later course after the first week. To predict sepsis, MOFS or deaths in the first 48-72 h, the highest predictive accuracy has been objectified for procalcitonin and IL-8; the Sepsis-Related Organ Failure Assessment (SOFA)-score predicts the outcome in the first 48 h, and provides a daily assessment of treatment response with a high positive predictive value. Contrast-enhanced CT provides the highest diagnostic accuracy for necrotizing pancreatitis when performed after the first week of disease. Patients who suffer early organ dysfunctions or at risk of developing a severe disease require early intensive care treatment. Early vigorous intravenous fluid replacement is of foremost importance. The goal is to decrease the hematocrit or restore normal cardiocirculatory functions. Antibiotic prophylaxis has not been shown as an effective preventive treatment. Early enteral feeding is based on a high level of evidence, resulting in a reduction of local and systemic infection. Patients suffering infected necrosis causing clinical sepsis, pancreatic abscess or surgical acute abdomen are candidates for early intervention. Hospital mortality of SAP after interventional or surgical debridement has decreased in high volume centers to below 20%.

Severe acute pancreatitis: Clinical course and management

Severe acute pancreatitis (SAP) develops in about 25% of patients with acute pancreatitis (AP). Severity of AP is linked to the presence of systemic organ dysfunctions and/or necrotizing pancreatitis pathomorphologically. Risk factors determining independently the outcome of SAP are early multi-organ failure, infection of necrosis and extended necrosis (> 50%). Up to one third of patients with necrotizing pancreatitis develop in the late course infection of necroses. Morbidity of SAP is biphasic, in the first week strongly related to early and persistence of organ or multi-organ dysfunction. Clinical sepsis caused by infected necrosis leading to multi-organ failure syndrome (MOFS) occurs in the later course after the first week. To predict sepsis, MOFS or deaths in the first 48-72 h, the highest predictive accuracy has been objectified for procalcitonin and IL-8; the Sepsis-Related Organ Failure Assessment (SOFA)-score predicts the outcome in the first 48 h, and provides a daily assessment of treatment response with a high positive predictive value. Contrast-enhanced CT provides the highest diagnostic accuracy for necrotizing pancreatitis when performed after the first week of disease. Patients who suffer early organ dysfunctions or at risk of developing a severe disease require early intensive care treatment. Early vigorous intravenous fluid replacement is of foremost importance. The goal is to decrease the hematocrit or restore normal cardiocirculatory functions. Antibiotic prophylaxis has not been shown as an effective preventive treatment. Early enteral feeding is based on a high level of evidence, resulting in a reduction of local and systemic infection. Patients suffering infected necrosis causing clinical sepsis, pancreatic abscess or surgical acute abdomen are candidates for early intervention. Hospital mortality of SAP after interventional or surgical debridement has decreased in high volume centers to below 20%.

New advances in pancreatic surgery

PURPOSE OF REVIEW

New understanding of the dynamic of acute pancreatitis, the clinical impact of local pathology in chronic pancreatitis and cystic neoplastic lesions bearing high potential for malignant transformation has changed the management of pancreatic diseases.

RECENT FINDINGS

In acute pancreatitis, risk factors independently determining outcome in severe acute pancreatitis are early and persistent multiorgan failure, infected necrosis and extended sterile necrosis. The management of severe acute pancreatitis is based on early intensive-care treatment and late surgical debridement. In chronic pancreatitis, recent data from randomized controlled clinical trials have demonstrated duodenum-preserving pancreatic head resection with an inflammatory mass of the head as superior to pylorus-preserving Whipple resection. Cystic neoplasms are local lesions of the pancreas with high malignant potential. Local organ-preserving resection techniques have been applied with low morbidity and mortality, replacing a Whipple-type resection. Resection of pancreatic cancer is ineffective to cure patients. After an R0-resection, a significant survival benefit has been achieved when adjuvant chemotherapy has additionally been applied.

SUMMARY

New knowledge about the nature of inflammatory diseases, cystic neoplastic lesions and malignant pancreatic tumours has changed the indication for surgical treatment and the application of organ-preserving surgical techniques.

Potential effects of PKC or protease inhibitors on acute pancreatitis-induced tissue injury in rats

BACKGROUND

Acute pancreatitis (AP) is still one of the severe diseases, that cause the development of multiple organ dysfunction with a high mortality. Effective therapies for AP are still limited, mainly due to unclear mechanisms by which AP initiates both pancreatic and extrapancreatic organ injury.

METHODS

Protease inhibitors (aprotinin, pefabloc, trypsin inhibitor) and PKC inhibitors (polymyxin B, staurosporine) were administrated 30 min before induction of AP in rats. To investigate the pancreatic, systemic and lung inflammatory response and injury, plasma IL-6 and IL-10, pancreatic and pulmonary myeloperoxidase (MPO) levels, pancreatic protease activity and phospholipase A(2) (PLA(2)) activity in ascites were measured 3 and 6 h after AP induction.

RESULTS

Pretreatment with protease inhibitors significantly prevented from AP-increased plasma levels of IL-10, pancreatic and pulmonary levels of MPO, pancreatic protease activity and the catalytic activity of PLA(2) in ascites. PKC inhibitors significantly reduced pancreatic and pulmonary levels of MPO and pancreatic protease activity.

CONCLUSION

Inhibition of proteases in AP may be helpful in ameliorating the inflammatory reaction in both pancreatic and extrapancreatic tissues, where neutrophil involvement may be regulated by PKC and proteases.

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Oxygen radical formation does not have an impact in the treatment of severe acute experimental pancreatitis using free cellular hemoglobin

AIM: Microcirculatory dysfunction and free oxygen radicals are important factors in the pathogenesis of severe acute pancreatitis. Additional oxygen delivery might enhance lipid peroxidation but may also improve pancreatic microcirculation. This study assesses the effect of free cellular bovine hemoglobin on the formation of oxygen radicals and microcirculation in a rodent model of severe acute pancreatitis.

METHODS: Fifteen minutes after induction of acute pancreatitis Wistar rats received either 0.8 mL bovine hemoglobin (HBOC-200), hydroxyethyl starch (HES) or 2.4 mL of normal saline to ensure normovolemic substitution. After 6 h of examination the pancreas was excised and rapidly processed for indirect measurement of lipid peroxidation products malondialdehyde (MDA) and reduced glutathione (GSH) in pancreatic tissue.

RESULTS: The single application of HBOC-200 improved pancreatic microcirculation and reduced histopathological tissue damage significantly. Tissue concentration of MDA did not differ between the groups. Also no differences in GSH levels were detected.

CONCLUSION: Though the single application of HBOC-200 and HES improve pancreatic microcirculation, no differences in lipid peroxidation products were detected. The beneficial effect of additional oxygen supply (HBOC-200) does not lead to enhanced lipid peroxidation.

Clinical significance of serum thioredoxin 1 levels in patients with acute pancreatitis

OBJECTIVE

Thioredoxin 1 (TRX-1), a redox-regulating protein with antioxidant activity, is induced by oxidative stress, and serum TRX-1 levels are recognized as an oxidative-stress marker. The aim of this study was to clarify the clinical significance of serum TRX-1 levels in patients with acute pancreatitis (AP) and evaluate the usefulness of this measurement in assessing disease severity.

METHODS

Serum TRX-1 levels were determined on admission in 18 patients with severe AP and 36 patients with mild AP. We also investigated the relationship between serum TRX-1 levels and clinical and laboratory data.

RESULTS

The median serum TRX-1 levels on admission were 54.9 ng/mL in mild AP and 118.8 ng/mL in severe AP. When the cutoff value for TRX-1 in predicting severe AP was determined to be 100 ng/mL, its sensitivity, specificity, and accuracy were 83.3%, 94.4%, and 90.7%, respectively. A significant correlation was observed between serum TRX-1 levels and Ranson score (r = 0.674), C-reactive protein (r = 0.718), interleukin 6 (r = 0.712), leukocyte count (r = 0.642), and serum amylase (r = 0.436).

CONCLUSIONS

Serum TRX-1 levels significantly correlate with AP severity. TRX-1 should constitute a reliable oxidative-stress marker for the evaluation of AP severity in relation to oxidative stress.

Antioxidants to prevent bovine neutrophil-induced mammary epithelial cell damage

Activated neutrophils are able to produce a large quantity of bactericidal molecules such as reactive oxygen species that have been associated with tissue damage in several inflammation models. The protective effects of antioxidants in a context of neutrophil-induced damage to mammary epithelial cells were first evaluated in vitro using a coculture model of activated bovine neutrophils and a bovine mammary epithelial cell line (MAC-T cells). Cell damage was determined by quantifying the release of lactate dehydrogenase by MAC-T cells in culture medium. Morphological observation of cells stained with acridine orange was used to visualize the extent of cell damage. When incubated with neutrophils activated by lipopolysaccharides and phorbol 12-myristate 13-acetate, MAC-T cells released large amounts of lactate dehydrogenase indicating significant cell damage. The addition of dimethylthiourea or bathocuproine disulfonic acid did not reduce the damage whereas catechin, deferoxamine or glutathione ethyl ester significantly reduced neutrophil-induced cytotoxicity in a dose-dependent manner. The effect of deferoxamine, an iron chelator, on the growth of Escherichia coli and the ability of bovine neutrophils to phagocytose these bacteria were then assessed in vitro. Our data showed that deferoxamine did not interfere with the phagocytic activity of neutrophils but inhibited growth of the bacteria. Overall, our results suggest that antioxidants may be effective tools for protecting mammary tissue against neutrophil-induced oxidative stress during bovine mastitis.

Effect of resveratrol on pancreatic oxygen free radicals in rats with severe acute pancreatitis

AIM: To investigate the therapeutic effects of resveratrol (RESV) as a free radical scavenger on experimental severe acute pancreatitis (SAP).

METHODS: Seventy-two male Sprague–Dawley rats were divided randomly into sham operation group, SAP group, and resveratrol-treated group. Pancreatitis was induced by intraductal administration of 0.1 mL/kg 4% sodium taurocholate. RESV was given intravenously at a dose of 20 mg/kg body weight. All animals were killed at 3, 6, 12 h after induction of the model. Serum amylase, pancreatic superoxide dismutase (SOD), malondialdehyde (MDA), and myeloperoxidase (MPO) were determined. Pathologic changes of the pancreas were observed under optical microscope.

RESULTS: The serum amylase, pancreatic MPO and the score of pathologic damage increased after the induction of pancreatitis, early (3, 6 h) SAP samples were characterized by decreased pancreatic SOD and increased pancreatic MDA. Resveratrol exhibited a protective effect against lipid peroxidation in cell membrane caused by oxygen free radicals in the early stage of SAP. This attenuation of the redox state impairment reduced cellular oxidative damage, as reflected by lower serum amylase, less severe pancreatic lesions, normal pancreatic MDA levels, as well as diminished neutrophil infiltration in pancreas.

CONCLUSION: RESV may exert its therapeutic effect on SAP by lowering pancreatic oxidative free radicals and reducing pancreatic tissue infiltration of neutrophils.

Extracellular cleavage of E-cadherin by leukocyte elastase during acute experimental pancreatitis in rats

BACKGROUND & AIMS

Cadherins play an important role in cell-cell contact formation at adherens junctions. During the course of acute pancreatitis, adherens junctions are known to dissociate-a requirement for the interstitial accumulation of fluid and inflammatory cells-but the underlying mechanism is unknown.

METHODS

Acute pancreatitis was induced in rats by supramaximal cerulein infusion. The pancreas and lungs were either homogenized for protein analysis or fixed for morphology. Protein sequencing was used to identify proteolytic cleavage sites and freshly prepared acini for ex vivo studies with recombinant proteases. Results were confirmed in vivo by treating experimental pancreatitis animals with specific protease inhibitors.

RESULTS

A 15-kilodalton smaller variant of E-cadherin was detected in the pancreas within 60 minutes of pancreatitis, was found to be the product of E-cadherin cleavage at amino acid 394 in the extracellular domain that controls cell-contact formation, and was consistent with E-cadherin cleavage by leukocyte elastase. Employing cell culture and ex vivo acini leukocyte elastase was confirmed to cleave E-cadherin at the identified position, followed by dissociation of cell contacts and the internalization of cleaved E-cadherin to the cytosol. Inhibition of leukocyte elastase in vivo prevented E-cadherin cleavage during pancreatitis and reduced leukocyte transmigration into the pancreas.

CONCLUSIONS

These data provide evidence that polymorphonuclear leukocyte elastase is involved in, and required for, the dissociation of cell-cell contacts at adherens junctions, the extracellular cleavage of E-cadherin, and, ultimately, the transmigration of leukocytes into the epithelial tissue during the initial phase of experimental pancreatitis.

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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.

Pathologic alterations detected in acute pancreatitis induced by sodium taurocholate in rats and therapeutic effects of curcumin, ciprofloxacin and metronidazole combination

BACKGROUND AND AIMS

Secondary bacterial infections and free radical injury have been known to play an important role in the pathogenesis and clinical outcome of acute pancreatitis. Despite the therapy models developed in recent years, the mortality rate is still reported to be higher than expected. The objective of this study therefore was to investigate the effectiveness of ciprofloxacin and metronidazole combination and curcumin together in the treatment of acute pancreatitis.

METHODS

Acute pancreatitis was induced in rats by sodium taurocholate (n = 60). Starting 6 h after the induction of acute pancreatitis, groups I and II were injected 200 mg/kg ciprofloxacin and 500 mg/kg metronidazole intraperitoneally every 12 h for 6 days. Groups II and III received 100 mg/kg curcumin since day 20 prior to the initiation of acute pancreatitis. On day 6, animals of all groups were killed. Blood and tissue samples were taken for biochemical, pathologic and bacteriologic examination.

RESULTS

No statistical difference in the treatment groups versus the non-treatment group has been detected in the pancreatic tissue on the basis of histopathological scoring results. Prevalences of bacterial translocation were significantly lower in the treatment groups (groups I-III) than in the non-treatment group (group IV) (p < 0.001, p < 0.001, p < 0.05, respectively). Serum amylase, lipase, malon dialdehyde and nitric oxide (except for nitric oxide level in group I), levels of groups I, II and III were significantly lower than those of group IV (p < 0.05).

CONCLUSIONS

The administration of ciprofloxacin and metronidazole in combination and curcumin in acute pancreatitis failed to provide a preventive effect on the occurrence of tissue injury, whereas free radical injury and prevalence of bacterial translocation were reduced significantly.

Kinetic study of TNF-alpha production and its regulatory mechanisms in acinar cells during acute pancreatitis induced by bile-pancreatic duct obstruction

Cytokines play a critical role in acute pancreatitis (AP) but the contribution of different cell sources to cytokine production is unclear. Unfortunately, there are no data concerning the molecular mechanisms involved in the inflammatory response in humans during AP. For this reason, the aim of this study was to analyse the ability of acinar cells, in comparison with leukocytes, to produce TNF-alpha at different stages of AP induced in rats by bile-pancreatic duct obstruction (BPDO) and to investigate the time course of oxidant-sensitive mechanisms involved in cytokine production. The role of oxygen free radicals as messengers of the mechanisms underlying acinar cell TNF-alpha production was assessed in BPDO rats treated with N-acetylcysteine (NAC). While monocytes were not able to produce TNF-alpha until 12 h after inducing AP, acinar cells triggered TNF-alpha production from 6 h after BPDO, at which time the pancreas develops maximal oxidative stress. Phosphorylated p38-MAPK and activated NF-kappaB were detected in acinar cells from 6 h after BPDO. NAC treatment reduced pancreatic glutathione depletion during the early stages of AP and attenuated the activation of p38-MAPK and NF-kappaB for 48 h following BPDO. As a result, acinar cells in NAC-treated rats failed to produce TNF-alpha during AP. In addition, NAC delayed monocyte TNF-alpha production, thereby maintaining low TNF-alpha levels in plasma during BPDO. In conclusion, acinar cells contribute directly to the inflammatory response during BPDO-induced AP by producing TNF-alpha even before inflammatory cells in the peripheral blood. The blockade of oxidant-mediated signal transduction pathways induced by NAC treatment prevented acinar cell TNF-alpha production.

mRNA for pancreatic uncoupling protein 2 increases in two models of acute experimental pancreatitis in rats and mice

Uncoupling-protein 2 (UCP2) is a mitochondrial protein that appears to be involved in cellular oxidant defense and in the regulation of oncotic cell death, both of which are important features of acute pancreatitis. However, UCP2 expression in acute pancreatitis has not been previously reported. In the current experiments, pancreatic gene expression was studied by real-time reverse-transcription/polymerase chain reaction and Northern blots. Two models of acute experimental pancreatitis were investigated: cerulein-induced pancreatitis in mice at two different time points and taurocholate-induced pancreatitis in rats at two degrees of severity. After cerulein administration, acinar injury and leukocyte infiltration was significantly higher at 24 h compared with 12 h after the first injection of cerulein (P<0.05, P<0.005, respectively). UCP2 mRNA was unchanged at 12 h but was nearly 12-fold greater than control levels after 24 h (P<0.001). UCP2 gene expression correlated with acinar injury (r=0.69; P<0.001). By 72 h after taurocholate administration, the severe group had more necrosis than the mild group (P<0.005). Pancreatic UCP2 mRNA was increased fourfold in the severe group compared with controls (P<0.01). UCP2 expression correlated with parenchymal necrosis (r=0.61; P<0.01). Thus, pancreatic UCP2 mRNA increased in two models of acute pancreatitis. The increase in UCP2 gene expression was correlated with the severity of the disease. Up-regulation of UCP2 in the pancreas may be a protective response to oxidative stress, but this increase may also have a negative influence on cellular energy metabolism. Therefore, acinar UCP2 may be an important modifier of the severity of acute pancreatitis.