N-acetylcysteine prevents intra-acinar oxygen free radical production in pancreatic duct obstruction-induced acute pancreatitis

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.

The effect of N-acetyl-l-cysteine on inflammation after intraperitoneal mesh placement in a potentially contaminated environment: Experimental study in the rat

BACKGROUND

The use of prosthetic meshes in abdominal wall reconstruction is a well-established approach; however, in certain cases where a bowel resection coexists its application is disputed. Any underlying inflammatory process may augment adhesion formation which is a major postoperative complication. In this animal study, our aim was to investigate the effect of N-acetyl-l-cysteine (NAC) on adhesion formation and the expression of inflammatory markers when a mesh was used in a clean or a potentially contaminated environment.

METHODS

Sixty male Wistar rats were randomly and equally allocated in 3 groups: A, B and C. Animals in all groups underwent laparotomy, a prosthetic mesh was placed and chemoprophylaxis with ciprofloxacin was administered. In groups B and C an enterectomy was also performed. NAC was injected intraperitoneally in group C. Adhesion formation, IL-1a, IL-6, TNF-a and histological data including fibrosis, neutrophils' infiltration and neovascularization were assessed. Mesh samples were sent for cultivation.

RESULTS

Adhesion formation was significantly less and inflammation markers were also lower in group C compared to group B (p<0.05). Histological findings were significant for greater fibrosis, neutrophils' infiltration and neovascularization in group B compared to both group A and C. Regarding mesh cultures, more specimens were tested positive in group B (p <0.05). Outcomes between group A and C did not differ.

CONCLUSION

NAC effectively ameliorated adhesion formation and inflammation in a potentially septic environment where a prosthetic mesh was placed.

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.

Size and ligand effects of gold nanoclusters in alteration of organellar state and translocation of transcription factors in human primary astrocytes

Ultra-small gold nanoclusters (AuNCs) with designed sizes and ligands are gaining popularity for biomedical purposes and ultimately for human imaging and therapeutic applications. Human non-tumor brain cells, astrocytes, are of particular interest because they are abundant and play a role in functional regulation of neurons under physiological and pathological conditions. Human primary astrocytes were treated with AuNCs of varying sizes (Au10, Au15, Au18, Au25) and ligand composition (glutathione, polyethylene glycol, N-acetyl cysteine). Concentration and time-dependent studies showed no significant cell loss with AuNC concentrations <10 μM. AuNC treatment caused marked differential astrocytic responses at the organellar and transcription factor level. The effects were exacerbated under severe oxidative stress induced by menadione. Size-dependent effects were most remarkable with the smallest and largest AuNCs (10, 15 Au atoms versus 25 Au atoms) and might be related to the accessibility of biological targets toward the AuNC core, as demonstrated by QM/MM simulations. In summary, these findings suggest that AuNCs are not inert in primary human astrocytes, and that their sizes play a critical role in modulation of organellar and redox-responsive transcription factor homeostasis.

The Remedial Potential of Lycopene in Pancreatitis through Regulation of Autophagy

Autophagy is an evolutionarily conserved process that degrades damaged organelles and recycles macromolecules to support cell survival. However, in certain disease states, dysregulated autophagy can play an important role in cell death. In pancreatitis, the accumulation of autophagic vacuoles and damaged mitochondria and premature activation of trypsinogen are shown in pancreatic acinar cells (PACs), which are the hallmarks of impaired autophagy. Oxidative stress mediates inflammatory signaling and cytokine expression in PACs, and it also causes mitochondrial dysfunction and dysregulated autophagy. Thus, oxidative stress may be a mediator for autophagic impairment in pancreatitis. Lycopene is a natural pigment that contributes to the red color of fruits and vegetables. Due to its antioxidant activity, it inhibited oxidative stress-induced expression of cytokines in experimental models of acute pancreatitis. Lycopene reduces cell death through the activation of 5′-AMP-activated protein kinase-dependent autophagy in certain cells. Therefore, lycopene may ameliorate pancreatitis by preventing oxidative stress-induced impairment of autophagy and/or by directly activating autophagy in PACs.

The interplay between oxidative stress and bioenergetic failure in neuropsychiatric illnesses: can we explain it and can we treat it?

Nitro-oxidative stress and lowered antioxidant defences play a key role in neuropsychiatric disorders such as major depression, bipolar disorder and schizophrenia. The first part of this paper details mitochondrial antioxidant mechanisms and their importance in reactive oxygen species (ROS) detoxification, including details of NO networks, the roles of H₂O₂ and the thioredoxin/peroxiredoxin system, and the relationship between mitochondrial respiration and NADPH production. The second part highlights and identifies the causes of the multiple pathological sequelae arising from self-amplifying increases in mitochondrial ROS production and bioenergetic failure. Particular attention is paid to NAD⁺ depletion as a core cause of pathology; detrimental effects of raised ROS and reactive nitrogen species on ATP and NADPH generation; detrimental effects of oxidative and nitrosative stress on the glutathione and thioredoxin systems; and the NAD⁺-induced signalling cascade, including the roles of SIRT1, SIRT3, PGC-1α, the FOXO family of transcription factors, Nrf1 and Nrf2. The third part discusses proposed therapeutic interventions aimed at mitigating such pathology, including the use of the NAD⁺ precursors nicotinamide mononucleotide and nicotinamide riboside, both of which rapidly elevate levels of NAD⁺ in the brain and periphery following oral administration; coenzyme Q₁₀ which, when given with the aim of improving mitochondrial function and reducing nitro-oxidative stress in the brain, may be administered via the use of mitoquinone, which is in essence ubiquinone with an attached triphenylphosphonium cation; and N-acetylcysteine, which is associated with improved mitochondrial function in the brain and produces significant decreases in oxidative and nitrosative stress in a dose-dependent manner.

The compensatory antioxidant response system with a focus on neuroprogressive disorders

Major antioxidant responses to increased levels of inflammatory, oxidative and nitrosative stress (ONS) are detailed. In response to increasing levels of nitric oxide, S-nitrosylation of cysteine thiol groups leads to post-transcriptional modification of many cellular proteins and thereby regulates their activity and allows cellular adaptation to increased levels of ONS. S-nitrosylation inhibits the function of nuclear factor kappa-light-chain-enhancer of activated B cells, toll-like receptor-mediated signalling and the activity of several mitogen-activated protein kinases, while activating nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2 or NFE2L2); in turn, the redox-regulated activation of Nrf2 leads to increased levels and/or activity of key enzymes and transporter systems involved in the glutathione system. The Nrf2/Kelch-like ECH-associated protein-1 axis is associated with upregulation of NAD(P)H:quinone oxidoreductase 1, which in turn has anti-inflammatory effects. Increased Nrf2 transcriptional activity also leads to activation of haem oxygenase-1, which is associated with upregulation of bilirubin, biliverdin and biliverdin reductase as well as increased carbon monoxide signalling, anti-inflammatory and antioxidant activity. Associated transcriptional responses, which may be mediated by retrograde signalling owing to elevated hydrogen peroxide, include the unfolded protein response (UPR), mitohormesis and the mitochondrial UPR; the UPR also results from increasing levels of mitochondrial and cytosolic reactive oxygen species and reactive nitrogen species leading to nitrosylation, glutathionylation, oxidation and nitration of crucial cysteine and tyrosine causing protein misfolding and the development of endoplasmic reticulum stress. It is shown how these mechanisms co-operate in forming a co-ordinated rapid and prolonged compensatory antioxidant response system.

Myalgic encephalomyelitis/chronic fatigue syndrome: From pathophysiological insights to novel therapeutic opportunities

Myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS) is a common and disabling condition with a paucity of effective and evidence-based therapies, reflecting a major unmet need. Cognitive behavioural therapy and graded exercise are of modest benefit for only some ME/CFS patients, and many sufferers report aggravation of symptoms of fatigue with exercise. The presence of a multiplicity of pathophysiological abnormalities in at least the subgroup of people with ME/CFS diagnosed with the current international consensus "Fukuda" criteria, points to numerous potential therapeutic targets. Such abnormalities include extensive data showing that at least a subgroup has a pro-inflammatory state, increased oxidative and nitrosative stress, disruption of gut mucosal barriers and mitochondrial dysfunction together with dysregulated bioenergetics. In this paper, these pathways are summarised, and data regarding promising therapeutic options that target these pathways are highlighted; they include coenzyme Q₁₀, melatonin, curcumin, molecular hydrogen and N-acetylcysteine. These data are promising yet preliminary, suggesting hopeful avenues to address this major unmet burden of illness.

N-Acetylcysteine enhances the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation in rats with severe acute pancreatitis

BACKGROUND

Severe acute pancreatitis (SAP) is a high mortality disease, for which there is a lack of effective therapies. Previous research has demonstrated that bone marrow-derived mesenchymal stem cells (BMSCs), which have immunomodulatory and antioxidant properties, have potential for the treatment of SAP. It remains unclear, however, whether the free radical scavenger N-acetylcysteine (NAC) can enhance the therapeutic efficacy of BMSC transplantation in SAP. In this study, we investigated the effect of combining treatment with NAC and BMSCs in a rat model of SAP.

METHODS

SAP was induced by injection of sodium taurocholate into the pancreatic duct and, after successful induction of SAP, the rats were treated with BMSCs and NAC, either singly or in combination.

RESULTS

After 3 days, serum levels of amylase, proinflammatory factors, malondialdehyde, and reactive oxygen species were significantly decreased in animals treated with BMSCs or NAC, compared with vehicle-treated animals. In contrast, total glutathione, superoxide dismutase and catalase were markedly increased after treatment with BMSCs or NAC. However, oxidative stress markers and inflammatory factors were significantly improved in the SAP + BMSCs + NAC group compared with those in the SAP + NAC group and the SAP + BMSCs group.

CONCLUSIONS

Combined NAC and BMSC therapy was found to alleviate oxidative stress damage to the pancreas and to inhibit the inflammatory response to a significantly greater extent than single therapy with either BMSCs or NAC. Because NAC enhances the therapeutic efficacy of BMSC transplantation in a rat model of SAP, combined therapy may provide a promising new approach for the treatment of SAP.

Oxidative stress and pesticide disease: a challenge for toxicology

Introducción. En los últimos decenios, la síntesis de compuestos químicos ha producido un alto número de sustancias utilizadas para proteger los cultivos y las cosechas de las plagas. La mayoría de pesticidas han sido usados en grandes cantidades para fines agrícolas y la exposición tóxica a estos compuestos es un problema de gran envergadura para la toxicología, pues tiene impacto en la salud pública por su importante morbilidad y discapacidad. Así, las intoxicaciones agudas y crónicas pueden ser comunes entre trabajadores agrícolas y población general. Estos compuestos desencadenan mecanismos moleculares relacionados con la peroxidación lipídica, donde las especies reactivas de oxigeno pueden incrementar procesos oxidativos intracelulares.Objetivo. Realizar una revisión de la literatura científica relacionada con enfermedades por estrés oxidativo producido por pesticidas.Materiales y métodos. Revisión de artículos que utilizó las palabras clave Estrés oxidativo; Pesticidas; Peroxidación de lípido; Toxicidad. Se eligieron los artículos relacionados con las enfermedades por estrés oxidativo producido por pesticidas.Resultados. Se encontró que algunas enfermedades hematológicas, neurológicas, metabólicas y genotóxicas pueden estar relacionadas con la peroxidación lipídica que producen los pesticidas.Conclusión. Se presenta una revisión de la literatura científica sobre el estrés oxidativo, la peroxidación lipídica inducida por pesticidas y las diferentes enfermedades que pueden afectar a la población en general.

Influence of daily oral prophylactic selenium treatment on the dibutyltin dichloride (DBTC)-induced pancreatitis in rats

Dibutyltin dichloride (DBTC) is an organotin compound used as model for acute and chronic pancreatitis. Oxidative stress is one of the mechanisms of propagation of acinar cell injury in acute pancreatitis. Selenium is an essential cofactor in the antioxidant glutathione peroxidase pathway. Selenium levels are described to be subnormal in patients with acute and chronic pancreatitis. The aim of our studies was to determine the prophylactic effect of Na-selenite [5 mg kg^-1 body weight (b.w.) per os (p.o.) 7 days] on the pathogenesis and course of DBTC- induced pancreatitis. Male inbred rats (LEW-1W Charles River) of 150 g body weight were used in this study. Experimental pancreatitis was induced by intravenous administration of 6 mg kg^-1 b.w. DBTC in rats. Na-selenite was administered as daily oral dose of 5 mg kg^-1 b.w. 7 days before induction of DBTC-pancreatitis. Malondialdehyde (MDA) was measured for monitoring levels of oxidative stress. Elimination of DBTC was reflected as tin concentration in bile and urine. Organ changes were indicated by serum parameters as well as histology. A prophylactic Na-selenite application significantly diminished MDA- and bilirubin concentration in serum, activities of lipase and transaminases as well as organ injuries compared to DBTC- treated rats in the absence of Na-selenite. The prophylactic oral treatment with Na-selenite in the scope of DBTC-induced pancreatitis points to a reduced oxidative stress characterized by diminished MDA serum levels and a milder course of pancreatitis suggesting prophylactic substitution with Na-selenite to probably elicit beneficial effect on the clinical outcome in patients with endoscopic retrograde cholangiopancreatography (ERCP).

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.

Redox signaling in acute pancreatitis

Acute pancreatitis is an inflammatory process of the pancreatic gland that eventually may lead to a severe systemic inflammatory response. A key event in pancreatic damage is the intracellular activation of NF-κB and zymogens, involving also calcium, cathepsins, pH disorders, autophagy, and cell death, particularly necrosis. This review focuses on the new role of redox signaling in acute pancreatitis. Oxidative stress and redox status are involved in the onset of acute pancreatitis and also in the development of the systemic inflammatory response, being glutathione depletion, xanthine oxidase activation, and thiol oxidation in proteins critical features of the disease in the pancreas. On the other hand, the release of extracellular hemoglobin into the circulation from the ascitic fluid in severe necrotizing pancreatitis enhances lipid peroxidation in plasma and the inflammatory infiltrate into the lung and up-regulates the HIF-VEGF pathway, contributing to the systemic inflammatory response. Therefore, redox signaling and oxidative stress contribute to the local and systemic inflammatory response during acute pancreatitis.

The protective effects of Shen-Fu injection on experimental acute pancreatitis in a rat model

Objectives. In the present study, we investigated the protective effects of Shen-Fu injection (SFI) on a caerulein-induced rat pancreatitis (AP) model. Methods. SFI was given to rats in the SFI treated group through intraperitoneal injection. Blood and pancreas samples were collected for serological and histopathological studies. Results. Our results showed that AP caused significant decrease in tissue glutathione (GSH) and serum IL-4 and IL-10, while pancreatic malondialdehyde (MDA) and myeloperoxidase (MPO) were increased. Furthermore, TNF-α, IL-1β, amylase, and lipase levels were also significantly increased. On the other hand, SFI treatment reserved all these biochemical indices as well as histopathologic alterations that were induced by caerulein. Conclusion. Our findings suggest that the SFI protects against caerulein-induced AP in rats via modulation of cytokines, oxidative stress, and Nuclear Factor-kappa B (NF-κB) activity.

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.

Beneficial effects of the ethanol extract of Caesalpinia pyramidalis on the inflammatory response and abdominal hyperalgesia in rats with acute pancreatitis

ETHNOPHARMACOLOGICAL RELEVANCE

Caesalpinia pyramidalis Tul. (Fabaceae) is a plant found in the Northeast of Brazil that is popularly used to treat inflammation. Acute pancreatitis (AP) is an inflammatory disease for which abdominal pain is a relevant symptom. As there is no specific therapy for AP, we investigated the effect of the ethanol extract from the inner bark of C. pyramidalis (EECp) on the AP induced by common bile duct obstruction (CBDO) in rats.

MATERIAL AND METHODS

AP was induced in male Wistar rats (200-250 g, n=6-8) through laparotomy and subsequent CBDO. Animals were euthanized after 6 (G6h) or 24 h (G24h) of induction. In the G6h protocol, animals were pretreated with EECp (100-400 mg/kg, p.o.) or vehicle (Tween 80; 0.2%) 1h before CBDO or sham surgery. For the G24h protocol, rats were pretreated with EECp (400mg/kg, 1h before CBDO or 1 h before and 12 h after CBDO) or vehicle. The following parameters were measured: inflammatory/oxidative (myeloperoxidase activity and malondialdehyde formation in the pancreas and lung, leukocyte counts in the blood and serum nitrate/nitrite), enzymatic (serum amylase and lipase levels) and nociceptive (abdominal hyperalgesia).

RESULTS

Induction of AP by CBDO significantly increased all the parameters evaluated in both G6h and G24h protocols when compared with the respective sham group. In the G6h protocol, the EECp pretreatment (400 mg/kg) significantly reduced all these parameters, besides completely inhibiting abdominal hyperalgesia. The same profile of reduction was observed from two administrations of EECp in the G24h protocol, while one single dose of EECp was able to significantly reduce pancreatic MDA, serum lipase levels, leukocyte counts in the blood and abdominal hyperalgesia without affecting the other parameters in the G24h protocol. Furthermore, rutin was found in the EECp.

CONCLUSIONS

Our results demonstrated that EECp decreases inflammation, lipoperoxidation and hyperalgesia in CBDO-induced AP, making it of interest in future approaches to treat this condition.

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.

Calcium and reactive oxygen species in acute pancreatitis: friend or foe?

SIGNIFICANCE

Acute pancreatitis (AP) is a debilitating and, at times, lethal inflammatory disease, the causes and progression of which are incompletely understood. Disruption of Ca(2+) homeostasis in response to precipitants of AP leads to loss of mitochondrial integrity and cellular necrosis.

RECENT ADVANCES

While oxidative stress has been implicated as a major player in the pathogenesis of this disease, its precise roles remain to be defined. Recent developments are challenging the perception of reactive oxygen species (ROS) as nonspecific cytotoxic agents, suggesting that ROS promote apoptosis that may play a vital protective role in cellular stress since necrosis is avoided.

CRITICAL ISSUES

Fresh clinical findings have indicated that antioxidant treatment does not ameliorate AP and may actually worsen the outcome. This review explores the complex links between cellular Ca(2+) signaling and the intracellular redox environment, with particular relevance to AP.

FUTURE DIRECTIONS

Recent publications have underlined the importance of both Ca(2+) and ROS within the pathogenesis of AP, particularly in the determination of cell fate. Future research should elucidate the subtle interplay between Ca(2+) and redox mechanisms that operate to modulate mitochondrial function, with a view to devising strategies for the preservation of organellar function.

Montelukast, a selective cysteinyl leukotriene receptor 1 antagonist, reduces cerulein-induced pancreatic injury in rats

OBJECTIVES

This study was designed to evaluate the protective effect of the cysteinyl leukotriene receptor antagonist montelukast against pancreatic injury during acute pancreatitis.

METHODS

Acute pancreatitis was induced in rats by 20-μg/kg (intraperitoneal) cerulein given at 1-hour intervals within 4 hours. Montelukast was administered intraperitoneally at a dose of 10 mg/kg 15 minutes before the first cerulein injection. Six hours after the cerulein or saline injections, the animals were killed by decapitation. Blood samples were collected to analyze amylase, lipase, and the proinflammatory cytokines tumor necrosis factor α and interleukin 1β. Pancreas tissues were taken for the determination of tissue glutathione and malondialdehyde levels and Na,K-adenosine triphosphatase and myeloperoxidase activities. The extent of tissue injury was analyzed microscopically.

RESULTS

Acute pancreatitis caused significant decreases in tissue glutathione level and Na,K-adenosine triphosphatase activity, which were accompanied with significant increases in the pancreatic malondialdehyde level, myeloperoxidase activity, and plasma cytokine level. On the other hand, montelukast treatment reversed all these biochemical indices and histopathological alterations that were induced by cerulein.

CONCLUSIONS

These results suggest that cysteinyl leukotrienes may be involved in the pathogenesis of acute pancreatitis and that the cysteinyl leukotriene receptor antagonist, montelukast, might be of therapeutic value for treatment of acute pancreatitis.

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.

Correlation of nitric oxide and other free radicals with the severity of acute pancreatitis and complicated systemic inflammatory response syndrome

OBJECTIVES

To investigate the correlation of nitric oxide (NO) and other free radicals with the severity of acute pancreatitis (AP) and complicated systemic inflammatory response syndrome (SIRS).

METHODS

Fifty AP patients (24 simple AP patients and 26 patients with AP complicated by SIRS) were involved in the study. Fifty healthy volunteers were included as controls. Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were evaluated, and plasma NO, plasma lipid peroxides, plasma vitamin E, plasma beta-carotene, whole-blood glutathione (GSH), and the activity of plasma GSH peroxidase were measured.

RESULTS

Compared with the control group, the APACHE II scores heightened in the AP group, and the SIRS group had the highest APACHE II scores (P < 0.005, P < 0.001, respectively). Plasma NO and plasma lipid peroxides increased with the heightening APACHE II scores, demonstrating a significant linear positive correlation (r = 0.618, r = 0.577, respectively; P < 0.001). Plasma vitamin E, plasma beta-carotene, whole-blood GSH, and the activity of plasma GSH peroxidase decreased with the heightening APACHE II scores, demonstrating a significant linear negative correlation (r = -0.600, r = -0.609, r = -0.559, r = -0.592, respectively; P < 0.001).

CONCLUSIONS

Nitric oxide and other free radicals take part in the aggravation of oxidative stress and oxidative injury and may play important roles in the pathogenesis of AP and SIRS. It may be valuable to measure free radicals to predict the severity of AP.

Liver lipid peroxidation and antioxidant capacity in cerulein-induced acute pancreatitis

The aim of this study was to evaluate the role of oxidative damage in pancreatitis-induced hepatic injury. Thirty-five rats were divided into five groups (each of 7 rats): control, cerulein (100 microg/kg body weight), cerulein and pentoxifylline (12 mg/kg body weight), cerulein plus L-NAME (10 mg/kg body weight) and cerulein plus L-arginine (160 mg/kg body weight). The degree of hepatic cell degeneration differed significantly between groups. Mean malondialdehyde levels were 7.00 +/- 2.29, 20.89 +/- 10.13, 11.52 +/- 4.60, 18.69 +/- 8.56, and 8.58 +/- 3.68 nmol/mg protein for the control, cerulein, pentoxifylline, L-NAME, and L-arginine groups, respectively. Mean catalase activity was 3.20 +/- 0.83, 1.09 +/- 0.35, 2.05 +/- 0.91, 1.70 +/- 0.60, and 2.85 +/- 0.47 U/mg protein for the control, cerulein, pentoxifylline, L-NAME, and L-arginine groups, respectively, and mean glutathione peroxidase activity was 0.72 +/- 0.25, 0.33 +/- 0.09, 0.37 +/- 0.04, 0.34 +/- 0.07 and 0.42 +/- 0.1 U/mg protein for the control, cerulein, pentoxifylline, L-NAME, and L-arginine groups, respectively. Cerulein-induced liver damage was accompanied by a significant increase in tissue malondialdehyde levels (P < 0.05) and a significant decrease in catalase (P < 0.05) and GPx activities (P < 0.05). L-arginine and pentoxifylline, but not L-NAME, protected against this damage. Oxidative injury plays an important role not only in the pathogenesis of AP but also in pancreatitis-induced hepatic damage.

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.

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.

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.

From acute pancreatitis to end-organ injury: mechanisms of acute lung injury

BACKGROUND

Multi-organ dysfunction, and in particular lung injury, is often responsible for the unfavorable outcome of patients with severe acute pancreatitis. Understanding of the mechanisms by which local inflammation in the pancreas leads to end-organ injury is crucial for the development of new therapeutic strategies.

METHODS

A MEDLINE search was performed with the terms "acute pancreatitis," "lung injury," "inflammatory response," "SIRS," and "multi-organ dysfunction." Pertinent articles were selected for analysis.

RESULTS

Modulation of the inflammatory response using a combination of immunomodulatory agents may decrease the incidence of severe pancreatitis-related acute lung injury and acute respiratory distress syndrome.

CONCLUSION

Clinical trials are of utmost importance to establish the validity of such strategies.

Redox-sensitive modulation of CD45 expression in pancreatic acinar cells during acute pancreatitis

CD45, a transmembrane protein tyrosine phosphatase required for signal transduction in leukocytes, has recently been found in pancreatic acinar cells. We have investigated the relationship between kinetic expression of CD45 on acinar cells during acute pancreatitis (AP) and the ability of these cells to produce tumour necrosis factor-alpha (TNF-alpha) through mechanisms sensitive to the cellular redox state. Flow cytometric analysis showed a significant decrease in the constitutive expression of CD45 in acinar cells from six hours onwards after inducing AP by bile-pancreatic duct obstruction (BPDO) in parallel with a significant increase in acinar TNF-alpha production. Changes in protein expression on the acinar cell surface preceded CD45 mRNA down-regulation, which was not found until 12 hours after BPDO. N-Acetylcysteine treatment delayed and reduced the down-regulation of CD45 expression induced by AP and prevented acinar cells from producing TNF-alpha. Our results show that CD45 expression is down-regulated in acinar cells during acute pancreatitis by redox-sensitive mechanisms, and they support the notion that CD45 negatively controls the production of cytokines in pancreatic acinar cells.

Beneficial effect of N-acetylcysteine against organophosphate toxicity in mice

Recent studies showed that oxidative stress could be an important component of the mechanism of organophosphate (OP) compounds toxicity. The aim of present study was to investigate either prophylactic and therapeutic effects of N-acetylcysteine (NAC) against fenthion-induced oxidative stress in mice. Additionally, the effects on survival rates were investigated. Therefore, we determined the changes of the blood levels of glutathione (GSH), malondialdehyde (MDA), nitrite, and nitrate in blood or serum. Additionally, all animals were observed for 6 h and the survival rates were recorded. It was found that fenthion administration increased the levels of MDA, and decreased the levels of GSH, nitrite and nitrate. On the other hand, both prophylactic and therapeutic NAC treatment decreased the levels of MDA, and increased the levels of GSH, nitrite, and nitrate. The results showed that NAC is able to attenuate the fenthion-induced oxidative stress whereby NAC has not only prophylactic but also therapeutic activity in fenthion poisoning. On the other hand, we found that NAC can clearly improve survival rates in mice administered with an acute high dose of fenthion poisoning. In conclusion, NAC can decrease OP-induced oxidative stress and mortality rate, but the exact mechanism of its NAC protective effect needs to be explored further.

Acute pancreatitis: animal models and recent advances in basic research

Acute pancreatitis (AP) is characterized by edema, acinar cell necrosis, hemorrhage, and severe inflammation of the pancreas. Patients with AP present with elevated blood and urine levels of pancreatic digestive enzymes, such as amylase and lipase. Severe AP may lead to systemic inflammatory response syndrome and multiorgan dysfunction syndrome, which account for the high mortality rate of AP. Although most (>80%) cases of AP are associated with gallstones and alcoholism, some are idiopathic. Although the pathogenesis of AP has not yet been elucidated, a common feature is the premature activation of trypsinogen within pancreatic tissues, which triggers autodigestion of the gland. Recent advances in basic research suggest that etiologic factors including cyclooxygenase-2, substance P, and angiotensin II may have novel roles in this disease. Basic research data obtained thus far have been based on animal models of AP ranging from mild edematous pancreatitis to severe necrotizing pancreatitis. In view of this, an adequate selection of experimental animal models is of paramount importance. Notwithstanding these animal models, it should be emphasized that none of these models mimic the clinical situation where varying degrees of severity usually occur. In this review, commonly used animal models of AP will be critically evaluated. A discussion of recent advances in our knowledge about AP risk factors is also included.

Menadione-induced reactive oxygen species generation via redox cycling promotes apoptosis of murine pancreatic acinar cells

Oxidative stress may be an important determinant of the severity of acute pancreatitis. One-electron reduction of oxidants generates reactive oxygen species (ROS) via redox cycling, whereas two-electron detoxification, e.g. by NAD(P)H:quinone oxidoreductase, does not. The actions of menadione on ROS production and cell fate were compared with those of a non-cycling analogue (2,4-dimethoxy-2-methylnaphthalene (DMN)) using real-time confocal microscopy of isolated perfused murine pancreatic acinar cells. Menadione generated ROS with a concomitant decrease of NAD(P)H, consistent with redox cycling. The elevation of ROS was prevented by the antioxidant N-acetyl-l-cysteine but not by the NADPH oxidase inhibitor diphenyliodonium. DMN produced no change in reactive oxygen species per se but significantly potentiated menadione-induced effects, probably via enhancement of one-electron reduction, since DMN was found to inhibit NAD(P)H:quinone oxidoreductase detoxification. Menadione caused apoptosis of pancreatic acinar cells that was significantly potentiated by DMN, whereas DMN alone had no effect. Furthermore, bile acid (taurolithocholic acid 3-sulfate)-induced caspase activation was also greatly increased by DMN, whereas DMN had no effect per se. These results suggest that acute generation of ROS by menadione occurs via redox cycling, the net effect of which is induction of apoptotic pancreatic acinar cell death. Two-electron detoxifying enzymes such as NAD(P)H:quinone oxidoreductase, which are elevated in pancreatitis, may provide protection against excessive ROS and exert an important role in determining acinar cell fate.

Antioxidant N-acetylcysteine blocks nerve growth factor-induced H2O2/ERK signaling in PC12 cells

We investigated whether H2O2, superoxide, and ERK participate in nerve growth factor (NGF)-induced signaling cascades and whether antioxidant N-acetylcysteine (NAC) regulates these NGF-induced responses. PC12 cells were cultured in medium containing NGF or vehicle with or without NAC pretreatment, and the intracellular H2O2 and superoxide levels and the amount of phosphorylated ERK were evaluated by flow cytometry and Western blotting, respectively. We found that NGF increased intracellular H2O2 concentration and activated ERK but failed to affect intracellular superoxide level. Moreover, NAC counteracted these NGF-induced responses. These findings demonstrate that NAC blocks the NGF-induced H2O2/ERK signaling in PC12 cells.

Glutathione peroxidase and glutathione reductase activities are partially responsible for determining the susceptibility of cells to oxidative stress

Different cell types response differently to toxic insult. In a previous study, it was demonstrated that the C6 glioma cell is more sensitive to Cd induced oxidative stress than the HepG2 cells. To explain the difference between the two cell lines in their response to oxidative stress, it was hypothesized that the activity of glutathione metabolizing enzymes may be different. The objective of this study is to determine the activities of glutathione peroxidase (GPx) and glutathione reductase (GR) in the two cell lines and to explain how these differences may affect the susceptibility of the two cells to oxidative stress. In the HepG2 cells, the activity of GPx was 2.24+/-0.18 micromol/mg protein/min and that for GR was 5.63+/-0.58 micromol/mg protein/min. For the C6 glioma cells, GPx and GR activities were 1.29+/-0.14 and 1.07+/-0.11 micromol/mg protein/min, respectively. Using the kinetic equilibrium: K(eq)=([GSSG]x[NADPH]x[H(+)])/([GSH](2)x[NADP(+)]), and the GSH/GSSG previously published (HepG2: 2.6 and C6 glioma: 3.6), resting NADPH/NADP(+) for the cell lines were calculated. The results showed that NADPH/NADP(+) for HepG2 cells (17.8) is higher than that in the C6 glioma cells (10.8). These data supported the notion that the reducing power (NADPH/NADP(+)) in the HepG2 cells is higher than that in the C6 glioma cell and thus, the later would be more susceptible to oxidative stress. The results also suggested that besides GSH/GSSG, the activities of GPx and GR are important in predicting tissue redox state. Applying this hypothesis to animal tissues, the ratio of the activities of the two enzymes in mouse liver, cerebral cortex, hippocampus and cerebellum were measured. It was demonstrated that the activities of GPx and GR were different in the different tissues studied. The possible correlation between enzymatic activities and the redox state in the different tissues were discussed.

Influence of selenium treatment on the acute toxicity of dibutyltin dichloride in rats

BACKGROUND/AIMS

Dibutyltin dichloride (DBTC) is an organotin compound used as a model for acute pancreatitis. The aim was to determine the effect of various doses of Na-selenite on the pathogenesis and course of DBTC-induced toxic changes in organs and serum of rats.

METHODS

Experimental pancreatitis was induced by intravenous administration of 6 mg kg(-1) BW DBTC. Na-selenite was applied as a single intravenous dose of 5 mg kg(-1) BW and as daily oral dose of 1 mg kg(-1) BW. Malondialdehyde (MDA) was detected to observe the level of oxidative stress. The tin concentration in bile and urine shows the elimination of DBTC. Organ changes were indicated by serum parameters as well as histology.

RESULTS

DBTC causes an acute pancreatitis, cholestasis and liver lesions determined by specific elevated serum parameters and several histological lesions. Na-selenite significantly diminished MDA concentration, lipase, bilirubin and transaminases as well as organ injuries compared to only DBTC-treated rats.

CONCLUSIONS

The treatment with Na-selenite in the scope of DBTC-induced pancreatitis points to a reduced oxidative stress characterized by diminished MDA serum levels and a milder course of pancreatitis. The generation of DBTC-Na-selenite complexes could also be a mechanism to decrease the toxicity of organotin compounds like DBTC.

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.

AT1 receptor antagonism ameliorates acute pancreatitis-associated pulmonary injury

Acute pancreatitis (AP) is an inflammatory disease characterized by tissue edema, necrosis and hemorrhage. The mortality rate associated with this disease is particularly high when the inflammation has become systemic. Recently, activation of the pancreatic renin-angiotensin system (RAS) was shown to play a role in AP. The present study investigated whether administering an AT1 receptor antagonist decreases the severity of AP and pancreatitis-induced systemic inflammation, particularly pulmonary injury. Rats with AP-associated lung injury were induced by multiple doses of caerulein, which was demonstrated in the previous studies. Three injections of losartan (200 microg/ kg/h) were given 30 min prior to the first injection of caerulein. The results demonstrated that caerulein injections resulted in significant increases in pancreatic and pulmonary myeloperoxidase (MPO) activities, and losartan treatment attenuates these effects. Lung microvascular permeability was also significantly improved by losartan treatment. Losartan prevented caerulein-induced pancreatic and pulmonary morphological alterations, but not elevations in serum alpha-amylase or pancreas/body weight ratio. These data indicate that losartan treatment can attenuate pancreatic and lung injury. Thus, the implication is that a blockade of AT1 receptors may have a clinical application for the treatment of AP and, perhaps more importantly, subsequent pulmonary complications.

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.

Especies reactivas de oxígeno en las enfermedades inflamatorias del páncreas: ¿una posible diana terapéutica?

Chronic and acute pancreatitis can be understood as distinct stages of an inflammatory spectrum in the pancreas. Although its pathogenesis is not well defined, oxidative stress seems to be clearly involved in its development. During acute pancreatitis, there is an extraordinary and rapid formation of reactive oxygen species that leads to the extinction of pancreatic antioxidant reserves, causes direct tissue damage and activates oxidative cellular mediators, giving rise to the lesion. However, classical antioxidants have not been shown to have clear benefits in patients with acute pancreatitis. Chronic pancreatitis seems to be the result of a recurrent lesion and defective repair, leading to pancreatic atrophy and fibrosis. In this process, oxidative stress is an efficient stimulus to maintain pancreatic stellar cells active, the fibrogenic motor of chronic pancreatitis. Although antioxidant supplements relieve abdominal pain in these patients, the direction of future antioxidant therapies lies in identifying oxidative mechanisms with the potential for intervention.

Erythrocyte Adaptation to Oxidative Stress in Endurance Training

BACKGROUND

We tested the hypothesis that endurance training may reduce exercise oxidative stress damage on erythrocytes.

METHODS

Fifteen subjects performed a standardized endurance exercise at 75% of maximal oxygen consumption weekly during a 19-week training period. Blood samples taken before and after exercise were analyzed by Fourier transform-infrared (FT-IR) spectrometry to determine exercise-induced change in plasma concentrations and erythrocyte IR absorptions.

RESULTS

Training first induced a stabilization of plasma concentration changes during exercise (unchanged for glucose, increased for lactate, triglycerides, glycerol, and fatty acids), whereas erythrocyte phospholipid alterations remained elevated (p <0.05). Further, training reduced the exercise-induced erythrocyte lactate content increase (nuC-O; p <0.05) and phospholipid alterations (nuC-H(n) and nuP=O; p <0.05) during exercise. These changes paralleled the decrease of exercise-induced hemoconcentration (p <0.05) and plasma lactate increase (p <0.05).

CONCLUSIONS

These correlated changes between plasma and erythrocyte parameters suggest that endurance training reduces erythrocyte susceptibility to oxidative stress.

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.