N-acetylcysteine decreases severity of acute pancreatitis in mice

Targeting Endoplasmic Reticulum Stress as an Effective Treatment for Alcoholic Pancreatitis

Pancreatitis and alcoholic pancreatitis are serious health concerns with an urgent need for effective treatment strategies. Alcohol is a known etiological factor for pancreatitis, including acute pancreatitis (AP) and chronic pancreatitis (CP). Excessive alcohol consumption induces many pathological stress responses; of particular note is endoplasmic reticulum (ER) stress and adaptive unfolded protein response (UPR). ER stress results from the accumulation of unfolded/misfolded protein in the ER and is implicated in the pathogenesis of alcoholic pancreatitis. Here, we summarize the possible mechanisms by which ER stress contributes to alcoholic pancreatitis. We also discuss potential approaches targeting ER stress and UPR in developing novel therapeutic strategies for the disease.

Pharmacological prevention of post-operative pancreatitis: systematic review and meta-analysis of randomized controlled trials on animal studies

BACKGROUND

Postoperative pancreatic fistula (POPF) remains a significant complication of pancreatic resection with recent evidence showing a strong association between post-operative pancreatitis and subsequent development of POPF. Incidence and severity of pancreatitis following endoscopic therapy has been effectively reduced with indomethacin prophylaxis, however further agents require evaluation. We present a systematic literature review and meta-analysis of the prophylactic treatment with corticosteroids or n-acetyl cysteine (NAC) of induced pancreatitis in rodent models.

METHODS

A systematic literature search was conducted using Pubmed, Medline, Embase and Cochrane library to identify eligible randomized control trials (RCT) involving animal models that examined NAC or corticosteroids. The primary outcome was the subsequent effect on serum amylase and IL-6 and the histopathological markers of severity such as pancreatic oedema and necrosis.

RESULTS

Four RCTs (n = 178) met inclusion criteria examining NAC and eight RCTs (n = 546) examining corticosteroid agents (dexamethasone, hydrocortisone, methylprednisolone). Prophylactic administration of all corticosteroid agents showed a net effect in favour of reducing markers of severity of pancreatitis. NAC showed a significant reduction in severity of amylase and necrosis.

CONCLUSION

The RCTs examined suggest that prophylactic administration of corticosteroid agents and NAC can reduce the severity of pancreatitis as indicated by histopathologic markers, serum amylase and IL-6 levels.

N-Acetylcysteine Reduces the Pro-Oxidant and Inflammatory Responses during Pancreatitis and Pancreas Tumorigenesis

Pancreatitis, an inflammation of the pancreas, appears to be a main driver of pancreatic cancer when combined with Kras mutations. In this context, the exact redox mechanisms are not clearly elucidated. Herein, we treated mice expressing a Kras^G12D mutation in pancreatic acinar cells with cerulein to induce acute pancreatitis. In the presence of Kras^G12D, pancreatitis triggered significantly greater redox unbalance and oxidative damages compared to control mice expressing wild-type Kras alleles. Further analyses identified the disruption in glutathione metabolism as the main redox event occurring during pancreatitis. Compared to the wild-type background, Kras^G12D-bearing mice showed a greater responsiveness to treatment with a thiol-containing compound, N-acetylcysteine (NAC). Notably, NAC treatment increased the pancreatic glutathione pool, reduced systemic markers related to pancreatic and liver damages, limited the extent of pancreatic edema and fibrosis as well as reduced systemic and pancreatic oxidative damages. The protective effects of NAC were, at least, partly due to a decrease in the production of tumor necrosis factor-α (TNF-α) by acinar cells, which was concomitant with the inhibition of NF-κB(p65) nuclear translocation. Our data provide a rationale to use thiol-containing compounds as an adjuvant therapy to alleviate the severity of inflammation during pancreatitis and pancreatic tumorigenesis.

The effect of trimethazidine on mortality in an experimental acute pancreatitis model1

BACKGROUND/AIMS

Acute pancreatitis has a high morbidty and mortality. Its physiopathogenesis has not been enlightened up to the present. This study aims to investigate trimetazidine (antiischemic, antioxidant and cardioprotective agent) 's effects on the acute pancreatitis.

MATERIALS AND METHODS

In this study, four aqual groups are formed with 43 female Spraque-dawley type rats weighed between230-300 gr (mean 265 gr). 0.9% NaCl is injected intraperitoneally after laparotomy to the Group 1 (n=6). Group 2 (n=6) is control group that without any intervention. Acute pancreatitis is formed in Group 3 (n=16) via injection of Na-taurokolat in the common bile duct. Group 4 (n=15) is being formed pancreatitis and treated with Trimetazidine. In group 4 Trimetazidine 10 mg/kg/day drugs were given, 30 minutes, 24 and 72 hours after formation of acute pancreatitis, in three equal doses by orogastric way. In all groups, the rats have been laparatomised 72 hours later under general anesthesia and pancreas tissues has been extracted and studied histopathologically. Amylase, lipase, lactate dehydrogenase, aspartate transaminase, alanine tranaminase levels in the rats serum and superoxide dismutase, catalase, glutathione, malondialdehyde, nitric oxide, protein carbonyl, glutathione peroxidase levels in the rats tissue also have been looked up.

RESULTS

Serum and tissue findings and histopathologically examination of the pancreas tissues show significant decrease in the treatment group compare to study group.

CONCLUSION

Trimetazidine protects pancreas tissue and decreases the mortality by significantly lowering the biochemical and histopathological changes in the early stages of acute 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.

The Analgesic Effect of the Mitochondria-Targeted Antioxidant SkQ1 in Pancreatic Inflammation

Background. Chronic pancreatitis is one of the main risk factors for pancreatic cancer. In acute and chronic pancreatitis, oxidative stress is thought to play a key role. In this respect, the recently described mitochondria-targeted antioxidant SkQ1 effectively scavenges reactive oxygen species at nanomolar concentrations. Therefore, we aimed to characterize the influence of SkQ1 on tissue injury and pain in acute and chronic pancreatitis. Methods. Both acute and chronic pancreatitis were induced in C57BL/6 mice by intraperitoneal cerulein injections and treatment with SkQ1 was carried out by peroral applications. Hyperalgesia was assessed by behavioral observation and measurement of abdominal mechanical sensitivity. Blood serum and pancreatic tissue were harvested for analysis of lipase and histology. Results. SkQ1 did not influence pain, serological, or histological parameters of tissue injury in acute pancreatitis. In chronic pancreatitis, a highly significant reduction of pain-related behavior (p < 0.0001) was evident, but histological grading revealed increased tissue injury in SkQ1-treated animals (p = 0.03). Conclusion. After SkQ1 treatment, tissue injury is not ameliorated in acute pancreatitis and increased in chronic pancreatitis. However, we show an analgesic effect in chronic pancreatitis. Further studies will need to elucidate the risks and benefits of mitochondria-targeted antioxidants as an analgesic.

Reactive oxygen species, Ca(2+) stores and acute pancreatitis; a step closer to therapy?

Disruption of Ca(2+) homeostasis can lead to severe damage of the pancreas, resulting in premature activation of digestive enzymes, vacuolisation and necrotic cell death, features typical of acute pancreatitis (AP). Therefore a fine balance between Ca(2+) release from internal stores, Ca(2+) entry and extrusion mechanisms is necessary to avoid injury. Precipitants of AP induce Ca(2+) overload of the pancreatic acinar cell that causes mitochondrial dysfunction, via formation of the mitochondrial permeability transition pore (MPTP), loss of ATP production and consequent necrosis. Oxidative stress has been shown to occur in the development of AP and may modify Ca(2+) signalling events in the acinar cell. However, the precise pathophysiological involvement is currently unclear and antioxidant therapy in the clinic has largely proved ineffective. Possible reasons for this are discussed, including evidence that ROS generation may determine cell death patterns. In contrast, recent evidence has indicated the potential for AP therapy via the prevention of Ca(2+)-dependent mitochondrial damage. Multiple approaches are indicated from preclinical findings; 1) inhibition of Ca(2+) release by IP3R blockade, 2) inhibition of Ca(2+) entry through Orai1 blockade and 3) prevention of MPTP formation. Clinical trials of drugs which prevent mitochondrial dysfunction induced by Ca(2+) overload of pancreatic acinar cells are imminent and may provide patient benefit for a disease that currently lacks specific therapy.

Wnt activation protects against neomycin-induced hair cell damage in the mouse cochlea

Recent studies have reported the role of Wnt/β-catenin signaling in hair cell (HC) development, regeneration, and differentiation in the mouse cochlea; however, the role of Wnt/β-catenin signaling in HC protection remains unknown. In this study, we took advantage of transgenic mice to specifically knockout or overactivate the canonical Wnt signaling mediator β-catenin in HCs, which allowed us to investigate the role of Wnt/β-catenin signaling in protecting HCs against neomycin-induced damage. We first showed that loss of β-catenin in HCs made them more vulnerable to neomycin-induced injury, while constitutive activation of β-catenin in HCs reduced HC loss both in vivo and in vitro. We then showed that loss of β-catenin in HCs increased caspase-mediated apoptosis induced by neomycin injury, while β-catenin overexpression inhibited caspase-mediated apoptosis. Finally, we demonstrated that loss of β-catenin in HCs led to increased expression of forkhead box O3 transcription factor (Foxo3) and Bim along with decreased expression of antioxidant enzymes; thus, there were increased levels of reactive oxygen species (ROS) after neomycin treatment that might be responsible for the increased aminoglycoside sensitivity of HCs. In contrast, β-catenin overexpression reduced Foxo3 and Bim expression and ROS levels, suggesting that β-catenin is protective against neomycin-induced HC loss. Our findings demonstrate that Wnt/β-catenin signaling has an important role in protecting HCs against neomycin-induced HC loss and thus might be a new therapeutic target for the prevention of HC death.

Innate Immune Molecule Surfactant Protein D Attenuates Sepsis-induced Acute Pancreatic Injury through Modulating Apoptosis and NF-κB-mediated Inflammation

Sepsis causes multiple-organ dysfunction including pancreatic injury, thus resulting in high mortality. Innate immune molecule surfactant protein D (SP-D) plays a critical role in host defense and regulating inflammation of infectious diseases. In this study we investigated SP-D functions in the acute pancreatic injury (API) with C57BL/6 Wild-type (WT) and SP-D knockout (KO) mice in cecal ligation and puncture (CLP) model. Our results confirm SP-D expression in pancreatic islets and intercalated ducts and are the first to explore the role of pancreatic SP-D in sepsis. CLP decreased pancreatic SP-D levels and caused severe pancreatic injury with higher serum amylase 24 h after CLP. Apoptosis and neutrophil infiltration were increased in the pancreas of septic KO mice (p < 0.05, vs septic WT mice), with lower Bcl-2 and higher caspase-3 levels in septic KO mice (p < 0.05). Molecular analysis revealed increased NF-κB-p65 and phosphorylated IκB-α levels along with higher serum levels of TNF-α and IL-6 in septic KO mice compared to septic WT mice (p < 0.01). Furthermore, in vitro islet cultures stimulated with LPS produced higher TNF-α and IL-6 (p < 0.05) from KO mice compared to WT mice. Collectively, these results demonstrate SP-D plays protective roles by inhibiting apoptosis and modulating NF-κB-mediated inflammation in CLP-induced API.

Antioxidant drugs to prevent post-endoscopic retrograde cholangiopancreatography pancreatitis: What does evidence suggest?

AIM: To determine whether or not the use of antioxidant supplementation aids in the prevention of post- endoscopic retrograde cholangiopancreatography pancreatitis.

METHODS: A systematic review of randomized controlled trials (RCTs) was made to evaluate the preventive effect of prophylactic antioxidant supplementation in post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP). The inclusion criteria included: acute post-endoscopic retrograde cholangiopancreatography pancreatitis in adults; randomized clinical trials with the use of any antioxidant as an intervention compared with placebo, to reduce PEP. The outcome measure was the incidence and severity of PEP. Twelve RCTs involving 3110 patients since 1999 were included. The antioxidants used were selenite, β-carotene, and pentoxifylline (each one in one trial), N-acetylcysteine (NAC) in three trials, and allopurinol in six trials. The group of patients treated with NAC received different doses; either oral or intravenous, and allopurinol-treated patients received five different oral doses in two different administration periods. The results are expressed with raw numbers, proportions, as well as mean and standard deviations. The incidence of pancreatitis between groups was analyzed with Pearson’s χ² test or Fisher’s exact test (F). The main outcome is expressed as relative risks and 95%CI.

RESULTS: The incidence of pancreatitis in all antioxidant treatment groups was 8.6%, whereas it was 9.7% in the control group. The antioxidants used were selenite, β-carotene, and pentoxifylline (each one in one trial), NAC in three trials, and allopurinol in six trials. In allopurinol trials, three different dosifications were used; two trials reported a low dosage (of less than 400 mg), two trials reported a moderate dose (600 mg) and the remaining two employed higher doses (more than 900 mg). Supplementation was not associated with a significant reduction in the incidence of PEP [relative risk (RR) = 0.93; 95%CI: 0.82-1.06; P = 0.28]. In addition, the incidences of PEP in patients treated with allopurinol and those treated with other antioxidants were similar to that observed in patients who received the placebo (RR for trials with allopurinol, 0.92; 95%CI: 0.78-1.08; P = 0.31) and, with the use of other antioxidants, the incidence of PEP was 8.9%, whereas it was 9.7% in the control group (RR = 0.95; 95%CI: 0.77-1.18; P = 0.19).

CONCLUSION: Antioxidant supplementation shows no beneficial effect on the incidence of PEP. There is a lack of robust trials to support the use of antioxidants for prevention.

Effects of the mitochondria-targeted antioxidant mitoquinone in murine acute pancreatitis

Although oxidative stress has been strongly implicated in the development of acute pancreatitis (AP), antioxidant therapy in patients has so far been discouraging. The aim of this study was to assess potential protective effects of a mitochondria-targeted antioxidant, MitoQ, in experimental AP using in vitro and in vivo approaches. MitoQ blocked H2O2-induced intracellular ROS responses in murine pancreatic acinar cells, an action not shared by the control analogue dTPP. MitoQ did not reduce mitochondrial depolarisation induced by either cholecystokinin (CCK) or bile acid TLCS, and at 10 µM caused depolarisation per se. Both MitoQ and dTPP increased basal and CCK-induced cell death in a plate-reader assay. In a TLCS-induced AP model MitoQ treatment was not protective. In AP induced by caerulein hyperstimulation (CER-AP), MitoQ exerted mixed effects. Thus, partial amelioration of histopathology scores was observed, actions shared by dTPP, but without reduction of the biochemical markers pancreatic trypsin or serum amylase. Interestingly, lung myeloperoxidase and interleukin-6 were concurrently increased by MitoQ in CER-AP. MitoQ caused biphasic effects on ROS production in isolated polymorphonuclear leukocytes, inhibiting an acute increase but elevating later levels. Our results suggest that MitoQ would be inappropriate for AP therapy, consistent with prior antioxidant evaluations in this disease.

N-acetyl-L-cysteine sensitizes pancreatic cancers to gemcitabine by targeting the NFκB pathway

First-line therapy for pancreatic cancer is gemcitabine. Although tumors may initially respond to the gemcitabine treatment, soon tumor resistance develops leading to treatment failure. Previously, we demonstrated in human MIA PaCa-2 pancreatic cancer cells that N-acetyl-l-cysteine (NAC), a glutathione (GSH) precursor, prevents NFκB activation via S-glutathionylation of p65-NFκB, thereby blunting expression of survival genes. In this study, we documented the molecular sites of S-glutathionylation of p65, and we investigated whether NAC can suppress NFκB signaling and augment a therapeutic response to gemcitabine in vivo. Mass spectrometric analysis of S-glutathionylated p65-NFκB protein in vitro showed post-translational modifications of cysteines 38, 105, 120, 160 and 216 following oxidative and nitrosative stress. Circular dichroism revealed that S-glutathionylation of p65-NFκB did not change secondary structure of the protein, but increased tryptophan fluorescence revealed altered tertiary structure. Gemcitabine and NAC individually were not effective in decreasing MIA PaCa-2 tumor growth in vivo. However, combination treatment with NAC and gemcitabine decreased tumor growth by approximately 50%. NAC treatment also markedly enhanced tumor apoptosis in gemcitabine-treated mice. Compared to untreated tumors, gemcitabine treatment alone increased p65-NFκB nuclear translocation (3.7-fold) and DNA binding (2.5-fold), and these effects were blunted by NAC. In addition, NAC plus gemcitabine treatment decreased anti-apoptotic XIAP protein expression compared to gemcitabine alone. None of the treatments, however, affected extent of tumor hypoxia, as assessed by EF5 staining. Together, these results indicate that adjunct therapy with NAC prevents NFκB activation and improves gemcitabine chemotherapeutic efficacy.

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.

Duration of injury correlates with necrosis in caerulein-induced experimental acute pancreatitis: implications for pathophysiology

Pancreatic acinar cell necrosis is indicative of severe pancreatitis and the degree of necrosis is an index of its outcome. We studied whether the dose and duration of injury correlates with severity, particularly in terms of necrosis, in caerulein-induced acute pancreatitis (AP) in Swiss albino mice. In addition to control group 1 (G1), groups 2 and 3 received four injections of caerulein every hour but were sacrificed at five hours (G2) and nine hours (G3) respectively, and group 4 received eight injections and was sacrificed at nine hours (G4). The severity of pancreatitis was assessed histopathologically and biochemically. The histopathological scores of pancreatitis in groups 3 and 4 were significantly higher than in groups 1 and 2 (4 vs. 1, 4 vs. 2, 3 vs. 1, 3 vs. 2; P < 0.05). TUNEL-positive apoptotic cells were significantly higher in groups 2 and 3 compared with groups 1 and 4 (P < 0.05). Necrosis was significantly more in group 4 than other groups (37.49% (4.68) vs. 19.97% (1.60) in G2; 20.36% (1.56) in G3; P = 0.006 for G 2 vs. 4 and P = 0.019 for G 3 vs. 4). Electron microscopy revealed numerous autophagosomes in groups 2 and 3 and mitochondrial damage and necrosis in group 4. The pancreatic and pulmonary myeloperoxidase activity in group 4 was significantly higher than that in the other groups (P < 0.01). Hence, severity of pancreatitis is a function of the dose of injurious agent, while inflammation is both dose and duration dependent, which may also explain the wide spectrum of severity of AP seen in clinical practice.

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.

Oxidative stress in acute pancreatitis: lost in translation?

Oxidative stress has been implicated in the pathogenesis of acute pancreatitis, a severe and debilitating inflammation of the pancreas that carries a significant mortality, and which imposes a considerable financial burden on the health system due to patient care. Although extensive efforts have been directed towards the elucidation of critical underlying mechanisms and the identification of novel therapeutic targets, the disease remains without a specific therapy. In experimental animal models of acute pancreatitis, increased oxidative stress and decreased antioxidant defences have been observed, changes also detected in patients clinically. However, despite the promise of studies evaluating the effects of antioxidants in these model systems, translation to the clinic has thus far been disappointing. This may reflect many factors involved in the design of both preclinical and clinical evaluations of antioxidant therapy, not least the fact that most experimental studies have focussed on pre-treatment rather than post-injury assessment. This review has examined evidence relating to the involvement of oxidative stress in the pathophysiology of acute pancreatitis, focussing on experimental models and the clinical experience, including the experimental techniques employed and potential of antioxidant therapy.

Effect of L-cysteine on remote organ injury in rats with severe acute pancreatitis induced by bile-pancreatic duct obstruction

BACKGROUND

Remote organ failure occurs in cases of acute pancreatitis (AP); however, the reports on AP induced by pancreatic duct obstruction are rare. In this study we determined the effect of L-cysteine on pancreaticobiliary inflammation and remote organ damage in rats after pancreaticobiliary duct ligation (PBDL).

METHODS

AP was induced by PBDL in rats with 5/0 silk. Sixty rats were randomly divided into 4 groups. Groups A and B were sham-operated groups that received injections of saline or L-cysteine (10 mg/kg) intraperitoneally (15 rats in each group). Groups C and D were PBDL groups that received injections of saline or L-cysteine (10 mg/kg) intraperitoneally (15 rats in each group). The tissue samples of the pancreas and remote organs such as the lung, liver, intestine and kidney were subsequently examined for pathological changes under a light microscope. The samples were also stored for the determination of malondialdehyde and glutathione levels. Blood urea nitrogen (BUN), plasma amylase, ALT and AST levels were determined spectrophotometrically using an automated analyzer. Also, we evaluated the effect of L-cysteine on remote organ injury in rats with AP induced by retrograde infusion of 3.5% sodium taurocholate (NaTc) into the bile-pancreatic duct.

RESULTS

Varying degrees of injury in the pancreas, lung, liver, intestine and kidney were observed in the rats 24 hours after PBDL. The severity of injury to the lung, liver and intestine was attenuated, while injury status was not changed significantly in the pancreas and kidney after L-cysteine treatment. Oxidative stress was also affected by L-cysteine in PBDL-treated rats. The concentration of tissue malondialdehyde decreased in the pancreas and remote organs of PBDL and L-cysteine administrated rats, and the concentration of glutathione increased more significantly than that of the model control group. However, L-cysteine administration reduced the severity of injury in remote organs but not in the pancreas in rats with NaTc-induced AP.

CONCLUSION

L-cysteine treatment attenuated multiple organ damage at an early stage of AP in rats and modulated the oxidant/antioxidant imbalance.

Antioxidant supplementation for the prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis: a meta-analysis of randomized controlled trials

Background

Acute pancreatitis remains the most common major complication of endoscopic retrograde cholangiopancreatography (ERCP). The pathogenesis of post-ERCP acute pancreatitis may be mediated by oxygen-derived free radicals, which could be ameliorated by antioxidants. Antioxidant supplementation may potentially prevent post-ERCP pancreatitis. We performed a meta-analysis of randomized controlled trials to evaluate the effect of prophylactic antioxidant supplementation compared with control on the prevention of post-ERCP pancreatitis.

Methods

PubMed and Embase databases were searched to identify relevant trials. A standardized Excel file was used to extract data by two independent authors. Results were expressed as risk ratio (RR) with accompanying 95% confidence interval (CI). The meta-analysis was performed with the fixed-effects model or random-effects model according to heterogeneity.

Results

Eleven studies involving 3,010 patients met our inclusion criteria. Antioxidant supplementation did not significantly decrease the incidence of post-ERCP pancreatitis (RR, 0.92; 95% CI, 0.65-1.32; P = 0.665). There was also no statistical difference in the severity grades between the antioxidant group and control group.

Conclusions

Based on current evidence, antioxidant supplementation shows no beneficial effect on the incidence and the severity of post-ERCP pancreatitis; thus, there is currently a lack of evidence to support using antioxidants for the prevention of post-ERCP pancreatitis.

Prevention effects of ND-07, a novel drug candidate with a potent antioxidative action and anti-inflammatory action, in animal models of severe acute pancreatitis

Oxidative stress and inflammation both play major roles in the development of the acute pancreatitis. Currently, a pancreatic enzyme inhibitor with limited efficacy is only clinically available in a few countries, and antioxidants or non-steroidal anti-inflammatory drugs (NSAIDs) provide only partial tissue protection in acute pancreatitis animal models. Here, we introduce a new drug candidate for treating acute pancreatitis named ND-07 [chemical name: 2-acetoxy-5-(2-4-(trifluoromethyl)-phenethylamino)-benzoic acid] that exhibits both potent antioxidative and anti-inflammatory activities. In an electron spin resonance (ESR) study, ND-07 almost blocked hydroxyl radical generation as low as 0.05 μM and significantly suppressed DNA oxidation and cell death in a lipopolysaccharide (LPS)-stimulated pancreatic cell line. In a cerulein plus LPS-induced acute pancreatitis model, ND-07 pretreatment showed significant tissue protective effects, with reductions of serum amylase and lipase levels and pancreatic wet weights. ND-07 not only diminished the plasma levels of malondialdehyde (MDA) and nitric oxide but also significantly decreased prostaglandin E₂ (PGE₂) and expression of tumor necrotizing factor-alpha (TNF-α) in the pancreatic tissue. In a severe acute necrotizing pancreatitis model induced by a choline deficient, ethionine-supplemented (CDE) diet, ND-07 dramatically protected the mortality even without any death, providing attenuation of pancreas, lung, and liver damages as well as the reductions in serum levels of lactate dehydrogenase (LDH), amylase and lipase, MDA levels in the plasma and pancreatic tissues, plasma levels of TNF-α, and interleukin-1 (IL-1β). These findings suggest that current dual synergistic action mechanisms of ND-07 might provide a superior protection for acute pancreatitis than conventional drug treatments.

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.

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.

Hyperbaric oxygen and N-acetylcysteine treatment in L-arginine-induced acute pancreatitis in rats

BACKGROUND

This study was designed to evaluate the combined effects of hyperbaric oxygen (HBO) and N-acetylcysteine (NAC) on acute necrotizing pancreatitis in rats.

METHODS

Experiments were performed in 50 male Wistar rats, which were divided into five groups (N = 10 for each group). The first group received normal saline (0.9% NaCl) intraperitoneal and served as the control group. In the second group, acute pancreatitis was induced by 3.2-g/kg body weight L-arginine intraperitoneal twice at an interval of 1 hr, which has been shown previously to produce severe necrotizing acute pancreatitis. In the third group, NAC treatment (1000 mg/kg) was given after 1 hr of the induction of acute pancreatitis twice 24 hr apart. In the fourth group, animals received HBO, 6 hr after the induction of pancreatitis twice 12 hr apart. In the fifth group, animals received together NAC as in Group 3 and HBO treatment as in Group 4. Groups 1, 2, and 3 were left under normal atmospheric pressures. Twelve hours after last treatment, the animals were killed by exsanguinations. Blood samples were studied for amylase, calcium, and lactate dehydrogenase (LDH), pancreatic histology, pancreatic tissue malondialdehyde, superoxide dismutase, and glutathione levels.

RESULTS

Acute pancreatitis is reduced by the treatment of NAC, HBO, NAC + HBO. HBO + NAC groups performed statistically the best in preventing L-arginine-induced acute necrotising pancreatitis.

CONCLUSIONS

NAC especially combined with HBO, decreases oxidative stress parameters, serum amylase, calcium, and LDH levels, as well as histopathologic score.

2',4',6'-Tris(methoxymethoxy) chalcone (TMMC) attenuates the severity of cerulein-induced acute pancreatitis and associated lung injury

Acute pancreatitis (AP) is an inflammatory disease involving acinar cell injury and rapid production and release of inflammatory cytokines, which play a dominant role in local pancreatic inflammation and systemic complications. 2',4',6'-Tris (methoxymethoxy) chalcone (TMMC), a synthetic chalcone derivative, displays potent anti-inflammatory effects. Therefore, we aimed to investigate whether TMMC might affect the severity of AP and pancreatitis-associated lung injury in mice. We used the cerulein hyperstimulation model of AP. Severity of pancreatitis was determined in cerulein-injected mice by histological analysis and neutrophil sequestration. The pretreatment of mice with TMMC reduced the severity of AP and pancreatitis-associated lung injury and inhibited several biochemical parameters (activity of amylase, lipase, trypsin, trypsinogen, and myeloperoxidase and production of proinflammatory cytokines). In addition, TMMC inhibited pancreatic acinar cell death and production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 by inhibiting NF-κB and extracellular signal-regulated protein kinase 1/2 (ERK1/2) activation. Neutralizing antibodies for TNF-α, IL-1β, and IL-6 inhibited cerulein-induced cell death in isolated pancreatic acinar cells. Moreover, pharmacological blockade of NF-κB/ERK1/2 reduced acinar cell death and production of TNF-α, IL-1β, and IL-6 in isolated pancreatic acinar cells. In addition, posttreatment of mice with TMMC showed reduced severity of AP and lung injury. Our results suggest that TMMC may reduce the complications associated with pancreatitis.

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.

Pancreas-specific aquaporin 12 null mice showed increased susceptibility to caerulein-induced acute pancreatitis

Aquaporin 12 (AQP12) is the most recently identified member of the mammalian AQP family and is specifically expressed in pancreatic acinar cells. In vitro expression studies have revealed that AQP12 is localized at intracellular sites. To determine the physiological roles of AQP12 in the pancreas, we generated knockout mice for this gene (AQP12-KO). No obvious differences were observed under normal conditions between wild-type (WT) and AQP12-KO mice in terms of growth, blood chemistry, pancreatic fluid content, or histology. However, when we induced pancreatitis through the administration of a cholecystokinin-8 (CCK-8) analog, the AQP12-KO mice showed more severe pathological damage to this organ than WT mice. Furthermore, when we analyzed exocytosis in the pancreatic acini using a two-photon excitation imaging method, the results revealed larger exocytotic vesicles (vacuoles) in the acini of AQP12-KO mice at a high CCK-8 dose (100 nM). From these results, we conclude that AQP12 may function in the mechanisms that control the proper secretion of pancreatic fluid following rapid and intense stimulation.

Transsulfuration pathway defects and increased glutathione degradation in severe acute pancreatitis

Glutathione depletion is a consistent feature of the progression of mild to severe acute pancreatitis. In this study, we examined the temporal relationship between cysteine, homocysteine, and cysteinyl-glycine levels; total reduced erythrocyte glutathione; gamma-glutamyl transpeptidase activity; and disease severity. Initially, cysteine concentration was low, at levels similar to those of healthy controls. However, glutathione was reduced whilst cysteinyl glycine and gamma-glutamyl transpeptidase activity were increased in both mild and severe attacks. As the disease progressed, glutathione and cysteinyl glycine were further increased in mild attacks and cysteine levels correlated with homocysteine (r = 0.8, P < 0.001) and gamma-glutamyl transpeptidase activity (r = 0.75, P < 0.001). The progress of severe attacks was associated with glutathione depletion, reduced gamma-glutamyl transpeptidase activity, and increased cysteinyl glycine that correlated with glutathione depletion (r = 0.99, P = 0.01). These results show that glutathione depletion associated with severe acute pancreatitis occurs despite an adequate cysteine supply and could be attributed to heightened oxidative stress coupled to impaired downstream biosynthesis.

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.

Protective effects of N-acetylcysteine against liver injury in rats with severe acute pancreatitis

AIM: To investigate the role of nuclear factor-kappa B (NF-κB) activation in liver injury in rats with severe acute pancreatitis (SAP), and to explore the protective effect of N-acetylcysteine (NAC) against SAP-associated liver injury in rats.

METHODS: Forty-two Wistar male rats were divided into sham operation group (SO, n = 6), SAP group (n = 18), and SAP + NAC group (NAC, 300 mg/kg body wt, n = 18). SO group underwent laparotomy only. SAP model was established by retrograde injection of 50 g/L sodium taurocholate into the bili-pancreatic duct in Wistar rats. SAP + NAC group were given NAC 300 mg/kg body weight intaperitoneally 2 h before SAP model was established. Rats were sacrificed at 3, 6 and 12 h after operation. The liver and pancreas tissues were obtained to observe their pathological changes with light microscopy. The levels of serum ALT and AST were determined at three time points (8 rats for each time point). The expression of TNF-α mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). The activity of NF-κB in liver was examined by immunohistochemical methods.

RESULTS: The levels of serum ALT and AST increased significantly in SAP group as compared with those in SO group at 3, 6 and 12 h (ALT: 186.67 ± 27.28, 321.17 ± 56.14, 492.50 ± 69.77 vs 36.83 ± 7.02; AST: 255.50 ± 44.15, 343.17 ± 43.70, 425.33 ± 58.37 vs 41.67 ± 5.35; P < 0.05 or 0.01). The level of TNF-α mRNA in SAP group was significantly higher than that in SO group at 3, 6 and 12 h (0.37 ± 0.03, 0.77 ± 0.04, 0.54 ± 0.04 vs 0.24 ± 0.03; P < 0.05 or 0.01). The activity of NF-κB was also higher in SAP group than that in SO group at 3 or 6 h (51.95 ± 4.76, 24.67 ± 4.93 vs 9.33 ± 2.05; P < 0.01 or 0.05). Liver and pancreas pathological damages were more severe in SAP group than those in SO group under light microscope. In SAP + NAC group, the levels of serum ALT and AST (143.67 ± 16.62, 203.33 ± 25.41, 301.17 ± 26.82; 136.33 ± 26.27, 221.50 ± 38.31, 310.50 ± 38.17) decreased significantly in comparison with those in SAP group (P < 0.05 or 0.01), and the expression of TNF-α mRNA was significantly lower than that in SAP group at the three time points (0.25 ± 0.03, 0.50 ± 0.05, 0.43 ± 0.03, P < 0.05 or 0.01). The activity of NF-κB in SAP + NAC group was lower than that in SAP group at 3 or 6 h (37.60 ± 6.37, 12.88 ± 2.66, P < 0.05).

CONCLUSION: NF-κB activation and TNF-α mRNA up-regulation involve in the pathogenesis of liver injury in SAP rats. NAC at a dose of 300 mg/kg can alleviate the pathological damage to liver, and its mechanism might relate to inhibition of NF-κB activation and reduction of cytokines such as TNF-α.

Pharmacological approach to acute pancreatitis

The aim of the present review is to summarize the current knowledge regarding pharmacological prevention and treatment of acute pancreatitis (AP) based on experimental animal models and clinical trials. Somatostatin (SS) and octreotide inhibit the exocrine production of pancreatic enzymes and may be useful as prophylaxis against Post Endoscopic retrograde cholangiopancreatography Pancreatitis (PEP). The protease inhibitor Gabexate mesilate (GM) is used routinely as treatment to AP in some countries, but randomized clinical trials and a meta-analysis do not support this practice. Nitroglycerin (NGL) is a nitrogen oxide (NO) donor, which relaxes the sphincter of Oddi. Studies show conflicting results when applied prior to ERCP and a large multicenter randomized study is warranted. Steroids administered as prophylaxis against PEP has been validated without effect in several randomized trials. The non-steroidal anti-inflammatory drugs (NSAID) indomethacin and diclofenac have in randomized studies showed potential as prophylaxis against PEP. Interleukin 10 (IL-10) is a cytokine with anti-inflammatory properties but two trials testing IL-10 as prophylaxis to PEP have returned conflicting results. Antibodies against tumor necrosis factor-alpha (TNF-α) have a potential as rescue therapy but no clinical trials are currently being conducted. The antibiotics beta-lactams and quinolones reduce mortality when necrosis is present in pancreas and may also reduce incidence of infected necrosis. Evidence based pharmacological treatment of AP is limited and studies on the effect of potent anti-inflammatory drugs are warranted.

Protective effects of erythropoietin against acute lung injury in a rat model of acute necrotizing pancreatitis

AIM

To investigate the effect of exogenous erythro-poietin (EPO) administration on acute lung injury (ALI) in an experimental model of sodium taurodeoxycholate- induced acute necrotizing pancreatitis (ANP).

METHODS

Forty-seven male Wistar albino rats were randomly divided into 7 groups: sham group (n = 5), 3 ANP groups (n = 7 each) and 3 EPO groups (n = 7 each). ANP was induced by retrograde infusion of 5% sodium taurodeoxycholate into the common bile duct. Rats in EPO groups received 1000 U/kg intramuscular EPO immediately after induction of ANP. Rats in ANP groups were given 1 mL normal saline instead. All animals were sacrificed at postoperative 24 h, 48 h and 72 h. Serum amilase, IL-2, IL-6 and lung tissue malondialdehyde (MDA) were measured. Pleural effusion volume and lung/body weight (LW/BW) ratios were calculated. Tissue levels of TNF-alpha, IL-2 and IL-6 were screened immunohistochemically. Additionally, ox-LDL accumulation was assessed with immune-fluorescent staining. Histopathological alterations in the lungs were also scored.

RESULTS

The mean pleural effusion volume, calculated LW/BW ratio, serum IL-6 and lung tissue MDA levels were significantly lower in EPO groups than in ANP groups. No statistically significant difference was observed in either serum or tissue values of IL-2 among the groups. The level of tumor necrosis factor-alpha (TNF-alpha) and IL-6 and accumulation of ox-LDL were evident in the lung tissues of ANP groups when compared to EPO groups, particularly at 72 h. Histopathological evaluation confirmed the improvement in lung injury parameters after exogenous EPO administration, particularly at 48 h and 72 h.

CONCLUSION

EPO administration leads to a significant decrease in ALI parameters by inhibiting polymorphonuclear leukocyte (PMNL) accumulation, decreasing the levels of proinflammatory cytokines in circulation, preserving microvascular endothelial cell integrity and reducing oxidative stress-associated lipid peroxidation and therefore, can be regarded as a cytoprotective agent in ANP-induced ALI.

Protective effects of erythropoietin against acute lung injury in a rat model of acute necrotizing pancreatitis

AIM: To investigate the effect of exogenous erythro-poietin (EPO) administration on acute lung injury (ALI) in an experimental model of sodium taurodeoxycholate-induced acute necrotizing pancreatitis (ANP).

METHODS: Forty-seven male Wistar albino rats were randomly divided into 7 groups: sham group (n = 5), 3 ANP groups (n = 7 each) and 3 EPO groups (n = 7 each). ANP was induced by retrograde infusion of 5% sodium taurodeoxycholate into the common bile duct. Rats in EPO groups received 1000 U/kg intramuscular EPO immediately after induction of ANP. Rats in ANP groups were given 1 mL normal saline instead. All animals were sacrificed at postoperative 24 h, 48 h and 72 h. Serum amilase, IL-2, IL-6 and lung tissue malondialdehyde (MDA) were measured. Pleural effusion volume and lung/body weight (LW/BW) ratios were calculated. Tissue levels of TNF-α, IL-2 and IL-6 were screened immunohistochemically. Additionally, ox-LDL accumulation was assessed with immune-fluorescent staining. Histopathological alterations in the lungs were also scored.

RESULTS: The mean pleural effusion volume, calculated LW/BW ratio, serum IL-6 and lung tissue MDA levels were significantly lower in EPO groups than in ANP groups. No statistically significant difference was observed in either serum or tissue values of IL-2 among the groups. The level of tumor necrosis factor-α (TNF-α) and IL-6 and accumulation of ox-LDL were evident in the lung tissues of ANP groups when compared to EPO groups, particularly at 72 h. Histopathological evaluation confirmed the improvement in lung injury parameters after exogenous EPO administration, particularly at 48 h and 72 h.

CONCLUSION: EPO administration leads to a significant decrease in ALI parameters by inhibiting polymorphonuclear leukocyte (PMNL) accumulation, decreasing the levels of proinflammatory cytokines in circulation, preserving microvascular endothelial cell integrity and reducing oxidative stress-associated lipid peroxidation and therefore, can be regarded as a cytoprotective agent in ANP-induced ALI.

Oxidative stress is enhanced by hypothermia imposed on cerulein-induced pancreatitis in rats

BACKGROUND

Hypothermia is a frequent event in severe acute pancreatitis (AP) and its real effects on the normal pancreas have not been well demonstrated. Moreover, neither have its effects on the outcome of acute pancreatitis been fully investigated. One hypothesis is that oxidative stress may be implicated in lesions caused or treated by hypothermia.

AIM OF THE STUDY

To investigate the effect of hypothermia in cerulein-induced acute pancreatitis (CIAP) in rats and the role played by oxidative stress in this process.

METHODS

Male Wistar rats were divided into hypothermic and normothermic groups. Hypothermia was induced with a cold mattress and rectal temperature was kept at 30 masculineC for one hour. Acute pancreatitis was induced with 2 doses of cerulein (20 ìg/kg) administered at a one-hour interval. Serum amylase, pancreas vascular permeability by Evan's blue method, pancreas wet-to-dry weight ratio and histopathology were analyzed in each group.

RESULTS

When compared with normothermic rats, hypothermic animals, with cerulein-induced acute pancreatitis, showed higher levels of pancreatic vascular permeability (p < 0.05), pancreas wet-to-dry weight ratio (p = 0.03), and histologically verified edema (p < 0.05), but similar serum amylase levels. The hypothermic group showed a higher oxidized-reduced glutathione ratio than the normothermic group.

CONCLUSION

Moderate hypothermia produced a greater inflammatory response in established acute pancreatitis induced by cerulein in rats. Moreover, this study suggests that oxidative stress may be one of the mechanisms responsible for the worse outcome in hypothermic rats with cerulein-induced acute pancreatitis.

Treatment with anti-factor VIIa in acute pancreatitis in rats: blocking both coagulation and inflammation?

OBJECTIVE

Acute pancreatitis starts as an autodigestive process restricted to the pancreas and progresses to a systemic inflammation via cytokine release into the blood stream. Several inhibitors of the coagulation cascade, including active-site-inactivated factor VIIa, have shown anti-inflammatory properties in other inflammatory models than acute pancreatitis. Free radical scavengers have proven useful in reducing the oxidative damage during hyperinflammatory conditions. The aim of this study was to investigate whether pretreatment with FVIIai would have any effect on the multiple organ dysfunction syndrome (MODS) in severe acute pancreatitis.

MATERIAL AND METHODS

Experimental acute pancreatitis was induced by intraductal infusion of taurodeoxycholate in the pancreatic duct. The animals were pretreated with N-acetyl-cysteine and active-site-inactivated factor VIIa. Neutrophil infiltration in the lungs, ileum and colon was quantified by myeloperoxidase activity. Inflammatory markers, IL-6 and MIP-2, were measured using ELISA.

RESULTS

Tissue infiltration of neutrophils in the lungs, ileum and colon significantly increased during acute pancreatitis as compared to sham operation. These levels were reduced by pretreatment with N-acetylcysteine and active-site-inactivated factor VIIa. Levels of interleukin-6 and macrophage inflammatory protein-2 increased significantly during acute pancreatitis. Pretreatment with NAC and FVIIai reduced these levels.

CONCLUSIONS

Both N-acetylcysteine and active-site-inactivated factor VIIa showed powerful anti-inflammatory properties in experimental acute pancreatitis. As they exert their effects through different physiological mechanisms, they represent potential candidates for future multimodal treatment of acute pancreatitis.

Ultrastructural clues for the protective effect of ascorbic acid and N-acetylcysteine against oxidative damage on caerulein-induced pancreatitis

BACKGROUND

Oxygen free radicals (OFR) have been implicated in the induction of acute pancreatitis (AP).

AIMS

The aim of this study was to determine the effect of ascorbic acid and N-acetylcysteine (NAC), potent antioxidants, against oxidative stress in AP.

METHODS

AP was induced by two i.p. injections of caerulein at 2-hour intervals (50 microg/kg BW). One group received additionally an antioxidant mixture composed of L(+)-ascorbic acid (14.3 mg/kg BW) and NAC (181 mg/kg BW) i.p. The rats were sacrificed 12 h after the last injection. Oxidative stress markers were evaluated. Light-microscopic and ultrastructural examination was performed.

RESULTS

Formation of vacuoles, mitochondrial damage, and dilatation of rough endoplasmic reticulum, margination and clumping of chromatin were major ultrastructural alterations in AP group. Ascorbic acid + NAC prevented these changes. Small vacuoles were present within the cytoplasm of some of the acinar cells. Pancreas damage was accompanied by an increase in tissue malondialdehyde (MDA) levels (p < 0.05), whereas a decrease was seen in catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) activities and total glutathione (GSH) levels (p < 0.005). Ascorbic acid + NAC decreased MDA levels but increased CAT, SOD, GPx activities and GSH levels (p < 0.005).

CONCLUSION

These results suggest that ascorbic acid + NAC is potentially capable of limiting pancreatic damage produced during AP via protecting fine structure of acinar cells and tissue antioxidant enzyme activities.

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N-acetylcysteine does not prevent post-endoscopic retrograde cholangiopancreatography hyperamylasemia and acute pancreatitis

AIM: Acute pancreatitis (AP) is the most common and often severe complication of endoscopic retrograde cholangiopancreatography (ERCP). The early step in the pathogenesis of acute pancreatitis is probably the capillary endothelial injury mediated by oxygen-derived free radicals. N-acetylcysteine - a free radical scavenger may be potentially effective in preventing post-ERCP acute pancreatitis and it is also known that N-acetylcysteine (ACC) can reduce the severity of disease in experimental model of AP.

METHODS: One hundred and six patients were randomly allocated to two groups. Fifty-five patients were given N-acetylcysteine (two 600 mg doses orally 24 and 12 h before ERCP and 600 mg was given iv, twice a day for two days after the ERCP). The control group consisted of 51 patients who were given iv. isotonic saline twice a day for two days after the ERCP. Serum and urine amylase activities were measured before ERCP and 8 and 24 h after the procedure. The primary outcome parameter was post-ERCP acute pancreatitis and the secondary outcome parameters were differences between groups in serum and urine amylase activity.

RESULTS: There were no significant differences in the rate of post-ERCP pancreatitis between two groups (10 patients overall, 4 in the ACC group and 6 in the control group). There were also no significant differences in baseline and post-ERCP serum and urine amylase activity between ACC group and control group.

CONCLUSION: N-acetylcysteine fails to demonstrate any significant preventive effect on post-ERCP pancreatitis, as well as on serum and urine amylase activity.

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.

Effects of N-acetylcysteine on acute necrotizing pancreatitis in rats

The aim of this study was to investigate the influence of N-acetylcysteine (NAC) on acute necrotizing pancreatitis (ANP) induced by glycodeoxycholic acid in rats. The induction of ANP resulted in significant increase in mortality rate, pancreatic necrosis and serum activity of amylase, alanine aspartate transferase (ALT), interleukin-6 (IL-6), lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, serum concentration of urea, tissue activity of myeloperoxidase (MPO) and malondialdehyde (MDA) in the pancreas and lung, and significant decrease of concentrations of calcium, blood pressure, urine output and pO(2). The use of NAC inhibited the changes in urine output, pO(2), tissue activity of MPO and MDA in pancreas and lungs, and the serum activity of IL-6, ALT, and serum concentrations of urea and calcium. NAC reduced the mortality and pancreatic damage. The use of NAC has a beneficial effect on the course of ANP in rats. It may be used in the treatment of acute pancreatitis.

Pro- and anti-inflammatory response of acinar cells during acute pancreatitis. Effect of N-acetyl cysteine

We investigate the ability of acinar cells to produce tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) at different stages of acute pancreatitis (AP). Since oxidative stress is involved in the inflammatory response, the effect of N-acetyl cysteine (NAC) has also been evaluated. AP was induced in rats by bile-pancreatic duct obstruction (BPDO). NAC (50 mg/kg) was administered 1h before and 1h after BPDO. Acinar cells were incubated for 4 h at 37 degrees C in 5% CO2 atmosphere in absence and presence of 24-h BPDO-PAAF (20%, v/v) as stimulant agent. Acinar production of TNF-alpha and IL-10 was analysed by flow cytometry. Plasma amylase activity and histological studies of the pancreas indicated the severity of AP. PAAF significantly stimulated the acinar production of TNF-alpha and IL-10 in control rats. TNF-alpha production was also significantly stimulated in acinar cells of rats with AP, although a decrease in the pro-inflammatory response was found from 6 h after BPDO onwards. However, acinar cells failed to produce IL-10 from 3 h after BPDO. The protective effect of NAC treatment against oxidative cell damage reduced the pancreatic injury and maintained and enhanced the ability of acinar cells to produce IL-10 at early AP stages. As long as acinar cells were not severely damaged in the course of AP, greater ability to produce cytokines in response to PAAF was found in those with higher forward scatter (R2 cells). We suggest that the capability of acinar cells to maintain an appropriate balance between the production of pro- and anti-inflammatory mediators could contribute to determine the degree of severity of AP.

Intravenous antioxidant modulation of end-organ damage in L-arginine-induced experimental acute pancreatitis

BACKGROUND

Oxidative stress mediates acinar injury in experimental acute pancreatitis (AP) and antioxidants are depleted in human AP. This study tests the hypothesis that exogenous antioxidant supplementation ameliorates experimental AP.

METHODS

Male Sprague-Dawley rats were randomly allocated to 1 of 4 groups (n = 5/group) and sacrificed at 72 h. AP was induced by 250 mg per 100 g body weight of 20% L-arginine hydrochloride in 0.15 mol/l sodium chloride. Group allocations were: group 1 (control) no intervention; group 2 AP; group 3 early multiple antioxidant (MAOX) intervention comprising 15 microg/kg selenium, 30 microg/kg ascorbate and 300 mg/kg N-acetylcysteine given at 6 and 30 h and group 4 the MAOX combination above given at 24 and 48 h. Endpoints were: serum amylase, antioxidant levels, bronchoalveolar lavage (BAL) protein and lung myeloperoxidase (MPO) activity and histological assessment of pancreatic injury.

RESULTS

L-arginine induced AP characterised by oedema, neutrophil infiltration, acinar cell degranulation and elevated serum amylase. Early MAOX reduced pulmonary MPO and BAL protein and reduced acinar swelling, degranulation and pancreatic parenchymal infiltration by inflammatory cells. These features were absent when intervention was delayed.

CONCLUSION

In this model, early but not late antioxidant intervention ameliorates pancreatic and pulmonary injury.

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.

Absence of the Major Zymogen Granule Membrane Protein, GP2, Does Not Affect Pancreatic Morphology or Secretion

The majority of digestive enzymes in humans are produced in the pancreas where they are stored in zymogen granules before secretion into the intestine. GP2 is the major membrane protein present in zymogen granules of the exocrine pancreas. Numerous studies have shown that GP2 binds digestive enzymes such as amylase, thereby supporting a role in protein sorting to the zymogen granule. Other studies have suggested that GP2 is important in the formation of zymogen granules. A knock-out mouse was generated for GP2 to study the impact of the protein on pancreatic function. GP2-deficient mice displayed no gross signs of nutrient malab-sorption such as weight loss, growth retardation, or diarrhea. Zymogen granules in the GP2 knock-out mice appeared normal on electron microscopy and contained the normal complement of proteins excluding GP2. Primary cultures of pancreatic acini appropriately responded to secretagogue stimulation with the secretion of digestive enzymes. The course of experimentally induced pancreatitis was also examined in the knock-out mice because proteins known to associate with GP2 have been found to possess a protective role. When GP2 knock-out mice were subjected to two different models of pancreatitis, no major differences were detected. In conclusion, GP2 is not essential for pancreatic exocrine secretion or zymogen granule formation. It is unlikely that GP2 serves a major intracellular role within the pancreatic acinar cell and may be functionally active after it is secreted from the pancreas.

Actin overexpression parallels severity of pancreatic injury

Among the three major cytofilament proteins, keratin (K8/K18/K19) expression increases nearly threefold upon pancreas or liver injury, while actin and tubulin expressions are considered relatively stable. K8/K18 serves essential hepatocyte cytoprotective functions yet appears dispensable in K8-null mouse pancreata, which led us to hypothesize that actin or tubulin expressions may increase after pancreatic injury. Balb/c and FVB/n mice manifested different susceptibility to injury in two pancreatitis models, with significant induction of actin protein (threefold) and RNA after moderate or severe but not mild injury. Alterations in tubulin expression were less prominent. Basally, K8-null and wild-type pancreata expressed similar actin and tubulin levels, while the injury-induced actin protein but not RNA was more pronounced in K8-null mice. K7/K18/K19/K20 were also induced in K8-null mice after injury. Ex vivo, caerulein-triggered pancreatitis caused protein degradation (actin approximately or = tubulin > keratins) and mRNA up-regulation that was blocked by actinomycin-D (act-D) (actin approximately or = tubulin approximately or = keratin) or by NF-kappaB inhibition (keratins > actin approximately or = tubulin). Hence, actin is not as static as previously held and is overexpressed after moderate to severe pancreatic injury while keratins are induced after minimal injury. Keratin and actin induction may serve protective roles in pancreatic injury.

Hyperamylasaemia and acute pancreatitis in paracetamol poisoning

BACKGROUND

Hyperamylasaemia and even acute pancreatitis have been reported in patients with paracetamol poisoning.

AIMS

To describe the incidence, clinical characteristics, and prognostic implications of hyperamylasaemia in paracetamol poisoning.

PATIENTS

Six hundred and two patients transferred to a specialized unit with severe paracetamol poisoning and 212 unselected patients admitted from the local region.

METHODS

Retrospective study based on hospital charts. The optimum threshold of serum amylase to discriminate non-survivors was identified.

RESULTS

An elevated serum amylase (>100 U/L) occurred in 28 of the unselected patients (13%), in 218 of the transferred patients (36%), and in 118 of 148 patients (80%) with fulminant hepatic failure. Only 33 cases of paracetamol-associated acute pancreatitis were diagnosed. A threshold serum amylase of 150 U/L to discriminate non-survivors had sensitivity 76%, specificity 85%, positive predictive value 33%, and negative predictive value 97%. In a logistic regression analysis, a serum amylase > 150 U/L was associated with an excess mortality (odds ratio 5.0, 2.6-9.7).

CONCLUSIONS

Hyperamylasaemia is frequent in patients with paracetamol poisoning, whereas clinical acute pancreatitis occurs rarely. The incidence of hyperamylasaemia increases with the degree of hepatic dysfunction. A serum amylase exceeding 1.5 times the upper normal limit indicates a poor prognosis.

Major pathological mechanisms of acute pancreatitis are prevented by N-acetylcysteine

AIM

To analyze the capability of N-acetylcysteine (NAC) to prevent major intra-acinar pathogenic mechanisms involved in the development of acute pancreatitis (AP).

METHODS

AP was induced by pancreatic duct obstruction (PDO) in rats. Some animals received NAC (50 mg/kg) 1 h before and 1 h after PDO. During a 24-hour period of PDO, plasma amylase activity and pancreatic glutathione and malondialdehyde levels were measured. Cytosolic Ca(2+) levels and enzyme (amylase and trypsinogen) load in acinar cells were also analyzed by flow cytometry, and histological analysis of the pancreas was performed by electron microscopy.

RESULTS

NAC avoided glutathione depletion at early AP stages, thereby preventing pancreatic oxidative damage, as reflected by normal malondialdehyde levels. By limiting oxidative stress, NAC treatment effectively prevented the impairment of Ca(2+) homeostasis found in acinar cells from early AP onwards, thus protecting the pancreas from damage. In addition, lower quantities of digestive enzymes were accumulated within acinar cells. This finding, together with the significantly lower hyperamylasemia observed in these animals, suggests that NAC treatment palliates the exocytosis blockade induced by PDO.

CONCLUSION

By preventing oxidative stress at early AP stages, NAC administration prevents other pathological mechanisms of AP from being developed inside acinar cells, thus palliating the severity of disease.

Ethanol differentially regulates NF-kappaB activation in pancreatic acinar cells through calcium and protein kinase C pathways

Mechanisms of alcoholic pancreatitis remain unknown. Previously, we showed that ethanol feeding sensitizes rats to pancreatitis caused by CCK-8, at least in part, by augmenting activation of the proinflammatory transcription factor NF-kappaB. To elucidate the mechanism of sensitization, here we investigate the effect of ethanol on Ca(2+)- and PKC-mediated pathways of CCK-induced NF-kappaB activation using an in vitro system of rat pancreatic acini incubated with ethanol. Ethanol augmented CCK-8-induced activation of NF-kappaB, similar to our in vivo findings with ethanol-fed rats. In contrast, ethanol prevented NF-kappaB activation caused by thapsigargin, an agent that mobilizes intracellular Ca(2+) bypassing the receptor. Pharmacological analysis showed that NF-kappaB activation by thapsigargin but not by CCK-8 is mediated through the calcineurin pathway and that the inhibitory effect of ethanol on the thapsigargin-induced NF-kappaB activation could be through inhibiting this pathway. Ethanol augmented NF-kappaB activation induced by the phorbol ester PMA, a direct activator of PKC. Inhibitory analysis demonstrated that Ca(2+)-independent (novel and/or atypical) PKC isoforms are involved in NF-kappaB activation induced by both CCK-8 and PMA in cells treated and not treated with ethanol. The results indicate that ethanol differentially affects the Ca(2+)/calcineurin- and PKC-mediated pathways of NF-kappaB activation in pancreatic acinar cells. These effects may play a role in the ability of ethanol to sensitize pancreas to the inflammatory response and pancreatitis.

Attenuated cerulein-induced pancreatitis in nuclear factor-kappaB-deficient mice

Nuclear factor (NF)-kappaB plays a central role in acute pancreatitis. We studied cerulein (CER)-induced pancreatitis in NF-kappaB knockout (KO) mice. NF-kappaB KO mice and normal control littermate wild-type (WT) mice were given four hyperstimulating doses of cerulein every hour to elicit secreatagogue-induced pancreatitis. Malonildialdehyde activity, glutathione levels, myeloperoxidase activity, TNF-alpha, and NF-kappaB binding activity and its inhibitory protein IkappaBalpha were studied in the pancreas. Furthermore, we measured plasma lipase and amylase and the histological damage. KO mice had reduced malonildialdehyde levels (WT + CER = 4.083 +/- 0.95 micromol/g; KO + CER = 1.513 +/- 0.63 microol/g), decreased myeloperoxidase activity (WT + CER = 19.3 +/- 2.39 mU/g; KO + CER = 10.21 +/- 2.05 mU/g), increased glutathione levels (WT + CER 6.22 +/- 2.46 micromol/g; KO + CER = 15. 516 +/- 2.92 micromol/g), and reduced serum levels of amylase (WT + CER = 2519 +/- 656.9 U/L; KO + CER = 916 +/- 280.4 U/L) and lipase (WT + CER = 1420 +/- 170 U/L; KO + CER = 861 +/- 172. 3 U/L). KO mice showed reduced pancreatic NF-kappaB activation, decreased TNF-alpha tissue content, and reduced histologic alterations. Our data suggest that KO mice have an attenuated cerulein-induced pancreatitis and help to define the possible interaction between NF-kappaB activation and oxidative stress in this deleterious event.