Heightened free radical activity in pancreatitis

Medical Management of Chronic Pancreatitis in Children: A Position Paper by the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Pancreas Committee

ABSTRACT

This position paper summarizes the current understanding of the medical management of chronic pancreatitis (CP) in children in light of the existing medical literature, incorporating recent advances in understanding of nutrition, pain, lifestyle considerations, and sequelae of CP. This article complements and is intended to integrate with parallel position papers on endoscopic and surgical aspects of CP in children. Concepts and controversies related to pancreatic enzyme replacement therapy (PERT), the use of antioxidants and other CP medical therapies are also reviewed. Highlights include inclusion of tools for medical decision-making for PERT, CP-related diabetes, and multimodal pain management (including an analgesia ladder). Gaps in our understanding of CP in children and avenues for further investigations are also reviewed.

Oxidative stress induces apoptosis via calpain- and caspase-3-mediated cleavage of ATM in pancreatic acinar cells

Oxidative stress-induced DNA cleavage and apoptosis in pancreatic acinar cells has been implicated in the pathogenesis of acute pancreatitis. Thus, an efficient DNA repair process is key to prevention of apoptotic pancreatic acinar cell death. Ataxia telangiectasia mutated (ATM), a sensor of DNA breaks, functions by recruiting DNA repair proteins to initiate the DNA repair process. In the present study, we investigated whether H₂O₂ produced by the action of glucose oxidase on α-D-glucose (G/GO) induces apoptosis in pancreatic acinar AR42J cells through an alteration of the level of ATM. As a result, G/GO induced apoptosis by promoting a loss of cell viability, increase in Bax, decrease in Bcl-2, cleavage of poly (ADP-ribose) polymerase (PARP) and fragmentation of DNA. In addition, ATM cleavage along with elevated levels of calpain and caspase-3 activity was induced by G/GO. By using ATM siRNA, we demonstrated that reduction in ATM levels enhanced G/GO-induced apoptosis. Moreover, inhibition of calpain activity by calpeptin or calpastatin, or by inhibition of caspase-3 with z-DEVD, suppressed G/GO-induced apoptosis and ATM cleavage. Collectively, these findings suggest that proteolysis of ATM is the underlying mechanism of apoptosis of pancreatic acinar cells caused by exposure to oxidative stress.

A Mini-Review on the Effect of Docosahexaenoic Acid (DHA) on Cerulein-Induced and Hypertriglyceridemic Acute Pancreatitis

Acute pancreatitis refers to the sudden inflammation of the pancreas. It is associated with premature activation and release of digestive enzymes into the pancreatic interstitium and systemic circulation, resulting in pancreatic tissue autodigestion and multiple organ dysfunction, as well as with increased cytokine production, ultimately leading to deleterious local and systemic effects. Although mechanisms involved in pathogenesis of acute pancreatitis have not been completely elucidated, oxidative stress is regarded as a major risk factor. In human acute pancreatitis, lipid peroxide levels in pancreatic tissues increase. Docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid (C22:6n-3), exerts anti-inflammatory and antioxidant effects on various cells. Previous studies have shown that DHA activates peroxisome proliferator-activated receptor-γ and induces catalase, which inhibits oxidative stress-mediated inflammatory signaling required for cytokine expression in experimental acute pancreatitis using cerulein. Cerulein, a cholecystokinin analog, induces intra-acinar activation of trypsinogen in the pancreas, which results in human acute pancreatitis-like symptoms. Therefore, DHA supplementation may be beneficial for preventing or inhibiting acute pancreatitis development. Since DHA reduces serum triglyceride levels, addition of DHA to lipid-lowering drugs like statins has been investigated to reduce hypertriglyceridemic acute pancreatitis. However, high DHA concentrations increase cytosolic Ca²⁺, which activates protein kinase C and may induce hyperlipidemic acute pancreatitis. In this review, effect of DHA on cerulein-induced and hypertriglyceridemic acute pancreatitis has been discussed. The relation of high concentration of DHA to hyperlipidemic acute pancreatitis has been included.

Docosahexaenoic acid inhibits IL-6 expression via PPARγ-mediated expression of catalase in cerulein-stimulated pancreatic acinar cells

Cerulein pancreatitis mirrors human acute pancreatitis. In pancreatic acinar cells exposed to cerulein, reactive oxygen species (ROS) mediate inflammatory signaling by Janus kinase (JAK) 2/signal transducer and activator of transcription (STAT) 3, and cytokine induction. Docosahexaenoic acid (DHA) acts as an agonist of peroxisome proliferator activated receptor γ (PPARγ), which mediates the expression of some antioxidant enzymes. We hypothesized that DHA may induce PPARγ-target catalase expression and reduce ROS levels, leading to the inhibition of JAK2/STAT3 activation and IL-6 expression in cerulein-stimulated acinar cells. Pancreatic acinar AR42J cells were treated with DHA in the presence or absence of the PPARγ antagonist GW9662, or treated with the PPARγ agonist troglitazone, and then stimulated with cerulein. Expression of IL-6 and catalase, ROS levels, JAK2/STAT3 activation, and nuclear translocation of PPARγ were assessed. DHA suppressed the increase in ROS, JAK2/STAT3 activation, and IL-6 expression induced nuclear translocation of PPARγ and catalase expression in cerulein-stimulated AR42J cells. Troglitazone inhibited the cerulein-induced increase in ROS and IL-6 expression, but induced catalase expression similar to DHA in AR42J cells. GW9662 abolished the inhibitory effect of DHA on cerulein-induced increase in ROS and IL-6 expression in AR42J cells. DHA-induced expression of catalase was suppressed by GW9662 in cerulein-stimulated AR42J cells. Thus, DHA induces PPARγ activation and catalase expression, which inhibits ROS-mediated activation of JAK2/STAT3 and IL-6 expression in cerulein-stimulated pancreatic acinar cells.

Antioxidant therapy for pain reduction in patients with chronic pancreatitis: a systematic review and meta-analysis

OBJECTIVES

Oxidative stress is strongly implicated in the pathogenesis of chronic pancreatitis (CP); however, clinical studies evaluating antioxidant therapy (AOT) in the management of CP pain have yielded conflicting results. The aim of this meta-analysis was to evaluate the efficacy of AOT in pain reduction in CP patients.

METHODS

Two authors independently conducted a comprehensive literature search from inception to December 2013. Relative risk (RR) and 95% confidence intervals (CIs) were calculated using the Mantel-Haenszel and DerSimonian-Laird methods.

RESULTS

Eight studies involving 446 patients (234 in AOT and 212 in control group) were included. Overall, CP patients who received AOT had significant reduction in pain compared with the control group (RR, 0.73; 95% CI, 0.58-0.91; P = 0.006). In the subgroup analysis, studies with predominantly alcoholic CP patients (RR, 0.60; 95% CI, 0.47-0.77; P < 0.0001) and studies with mean age of patients 42 years or older (RR, 0.66; 95% CI, 0.49-0.89; P = 0.006) showed significant benefit of AOT over placebo.

CONCLUSIONS

This is the first meta-analysis to summarize all the available evidence and show benefit of AOT in pain reduction in CP patients. There is a pressing need for well-designed larger studies with longer follow-up to better define the patient and disease factors favoring response, the optimal formulation, and duration of AOT.

Antioxidants for pain in chronic pancreatitis

BACKGROUND

Reduced intake and absorption of antioxidants due to pain and malabsorption are probable causes of the lower levels of antioxidants observed in patients with chronic pancreatitis (CP). Improving the status of antioxidants might be effective in slowing the disease process and reducing pain in CP.

OBJECTIVES

To assess the benefits and harms of antioxidants for the treatment of pain in patients with CP.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Conference Proceedings Citation Index from inception to October 2012. Two review authors performed the selection of trials independently.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) evaluating antioxidants for treatment of pain in CP. All trials were included irrespective of blinding, numbers of participants randomly assigned and language of the article.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. The risk of bias of included trials was assessed. Study authors were asked for additional information in the case of missing data.

MAIN RESULTS

Twelve RCTs with a total of 585 participants were included. Six trials were double-blinded, placebo-controlled studies, and the other six trials were of less adequate methodology. Most trials were small and had high rates of dropout. Eleven of the 12 included trials described the effects of antioxidants on chronic abdominal pain in chronic pancreatitis. Pain as measured on a visual analogue scale (VAS, scale range 0 to 10) after one to six months was less in the antioxidant group than in the control group (mean difference (MD) -0.33, 95% confidence interval (CI) -0.64 to -0.02, P value 0.04, moderate-quality evidence). The number of pain-free participants was not statistically significantly different (risk ratio (RR) 1.73, 95% CI 0.95 to 3.15, P value 0.07, low-quality evidence). More adverse events were observed in the antioxidant group, both in the parallel trials (RR 4.43, 95% CI 1.60 to 12.29, P value 0.0004, moderate-quality evidence) and in the cross-over trials (RR 5.80, 95% CI 1.56 to 21.53, P value 0.0009, moderate-quality evidence). Adverse events occurred in 16% of participants and were mostly mild (e.g. headache, gastrointestinal complaints), but were sufficient to make participants stop antioxidant use. Other important outcomes such as use of analgesics, exacerbation of pancreatitis and quality of life were rarely reported. One trial from 1991 evaluated the effects of antioxidants on acute pain during exacerbation of chronic pancreatitis and found that a significantly higher proportion of participants in the antioxidant group experienced pain relief. This trial was conducted more than 25 years ago and has not been reproduced since that time. Therefore, additional trials are needed before reliable conclusions can be drawn.

AUTHORS' CONCLUSIONS

Current evidence shows that antioxidants can reduce pain slightly in patients with chronic pancreatitis. The clinical relevance of this small reduction is uncertain, and more evidence is needed. Adverse events in one of six patients may prevent the use of antioxidants. Effects of antioxidants on other outcome measures, such as use of analgesics, exacerbation of pancreatitis and quality of life remain uncertain because reliable data are not available.

Reappraisal of xenobiotic-induced, oxidative stress-mediated cellular injury in chronic pancreatitis: A systematic review

AIM: To reappraise the hypothesis of xenobiotic induced, cytochrome P450-mediated, micronutrient-deficient oxidative injury in chronic pancreatitis.

METHODS: Individual searches of the Medline and Embase databases were conducted for each component of the theory of oxidative-stress mediated cellular injury for the period from 1^st January 1990 to 31^st December 2012 using appropriate medical subject headings. Boolean operators were used. The individual components were drawn from a recent update on theory of oxidative stress-mediated cellular injury in chronic pancreatitis.

RESULTS: In relation to the association between exposure to volatile hydrocarbons and chronic pancreatitis the studies fail to adequately control for alcohol intake. Cytochrome P450 (CYP) induction occurs as a diffuse hepatic and extra-hepatic response to xenobiotic exposure rather than an acinar cell-specific process. GSH depletion is not consistently confirmed. There is good evidence of superoxide dismutase depletion in acute phases of injury but less to support a chronic intra-acinar depletion. Although the liver is the principal site of CYP induction there is no evidence to suggest that oxidative by-products are carried in bile and reflux into the pancreatic duct to cause injury.

CONCLUSION: Pancreatic acinar cell injury due to short-lived oxygen free radicals (generated by injury mediated by prematurely activated intra-acinar trypsin) is an important mechanism of cell damage in chronic pancreatitis. However, in contemporary paradigms of chronic pancreatitis this should be seen as one of a series of cell-injury mechanisms rather than a sole mediator.

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 chronic pancreatitis: pathophysiological relevance and management

SIGNIFICANCE

Chronic pancreatitis (CP) is a progressive, inflammatory disease of the pancreas leading to slow destruction of pancreatic parenchyma and progressive fibrosis. The pathophysiological mechanism of CP is not well understood.

RECENT ADVANCES

A pathophysiologic role of oxidative stress in CP has, however, been suggested in recent years. Pancreatic acinar cells contain phase I cytochrome P450 (CYP 450) biotransforming enzymes and phase II conjugation reactions for the metabolism of xenobiotics. The oxidative stress in the acinar cell may result from generation of free radicals through CYP induction, concurrent exposure to a chemical that undergoes bioactivation, and insufficiency of micronutrients that are required to sustain antioxidant (AO) capacity.

CRITICAL ISSUES

Studies have shown that there is indeed a state of oxidative stress as evidenced by increased levels of products of oxidative stress and reduced AO capacity in patients with CP. A recent randomized, controlled trial has shown beneficial effect of AO therapy in CP; a combination of AOs (0.54 g ascorbic acid, 9000 IU β-carotene, 270 IU α-tocopherol, 600 μg organic selenium, and 2 g methionine per day in divided doses) led to significant reductions in pain and oxidative stress in patients with CP.

FUTURE DIRECTIONS

Similar studies from other centers and multicenter studies should confirm that oxidative stress plays an important role in the pathophysiology of CP and supplementation with AOs leads to significant pain relief in patients with this disease.

Antioxidant therapy in the management of acute, chronic and post-ERCP pancreatitis: A systematic review

We systematically reviewed the clinical trials which recruited antioxidants in the therapy of pancreatitis and evaluated whether antioxidants improve the outcome of patients with pancreatitis. Electronic bibliographic databases were searched for any studies which investigated the use of antioxidants in the management of acute pancreatitis (AP) or chronic pancreatitis (CP) and in the prevention of post-endoscopic retrograde cholangio-pancreatography (post-ERCP) pancreatitis (PEP) up to February 2009. Twenty-two randomized, placebo-controlled, clinical trials met our criteria and were included in the review. Except for a cocktail of antioxidants which showed improvement in outcomes in three different clinical trials, the results of the administration of other antioxidants in both AP and CP clinical trials were incongruent and heterogeneous. Furthermore, antioxidant therapy including allopurinol and N-acetylcysteine failed to prevent the onset of PEP in almost all trials. In conclusion, the present data do not support a benefit of antioxidant therapy alone or in combination with conventional therapy in the management of AP, CP or PEP. Further double blind, randomized, placebo-controlled clinical trials with large sample size need to be conducted.

Allopurinol in rat chronic pancreatitis: effects on pancreatic stellate cell activation

OBJECTIVES

Activation of pancreatic stellate cells (PSCs) is a key event in pancreatic fibrosis. Xanthine oxidase-derived free radicals are involved in the mechanism of chronic pancreatitis (CP). We here searched the in vivo effects of allopurinol on PSC activation and its relation to tissue oxidative stress and histological findings in rat CP.

METHODS

Rat CP was induced with intraductal trinitrobenzene sulfonic acid in groups 1 (n = 16) and 2 (n = 10). Group 3 (n = 10) received intraductal saline. Four weeks after induction, group 1 received allopurinol (200 mg/kg, s.c.), and groups 2 and 3 received saline. After 4 weeks, oxidative stress parameters, histological evaluation, and immunostaining for alpha-smooth muscle actin (+) PSCs were performed in the pancreata.

RESULTS

Oxidative stress parameters improved significantly in group 1 compared with groups 2 and 3. Collagen deposition and lobular/sublobular atrophy were significantly lower in group 1 than in group 2. Alpha-smooth muscle actin (+) PSCs counts in group 1 were significantly lower than in group 2, and were in correlation with the degree of fibrosis and atrophy.

CONCLUSIONS

Allopurinol inhibits PSC activation in vivo. Pancreatic fibrosis can be prevented, at least in part, by antioxidant treatment through xanthine oxidase metabolism. Long-term use of allopurinol and its analogs may be considered in clinical trials with CP.

Pain in chronic pancreatitis and pancreatic cancer

Chronic, debilitating abdominal pain is arguably the most important component of chronic pancreatitis, leading to significant morbidity and disability. Attempting to treat this pain, which is too often unsuccessful, is a frustrating experience for physician and patient. Multiple studies to improve understanding of the pathophysiology that causes pain in some patients but not in others have been performed since the most recent reviews on this topic. In addition, new treatment modalities have been developed and evaluated in this population. This review discusses new advances in neuroscience and the study of visceral pain mechanisms, as well as genetic factors that may play a role. Updates of established therapies, as well as new techniques used in addressing pain from chronic pancreatitis, are reviewed. Lastly, outcome measures, which have been highly variable in this field over the years, are addressed.

Ethanol induces secretion of oxidized proteins by pancreatic acinar cells

The pancreas is vulnerable to ethanol toxicity, but the pathogenesis of alcoholic pancreatitis is not fully defined. The intracellular oxidative balance and the characteristics of the secretion of isolated rat pancreatic acinar cells stimulated with the cholecystokinin analogue cerulein were assayed after acute oral ethanol (4 g/kg) load. Pancreatic acinar cells from ethanol-treated rats showed a significant (p < 0.02) lower content of total glutathione and protein sulfhydryls, and higher levels of oxidized glutathione (p < 0.03), malondialdehyde, and protein carbonyls (p < 0.05). Ethanol-intoxicated acinar cells showed a lower baseline amylase output compared to controls, with the difference being significantly exacerbated by cerulein stimulation. After cerulein, the release of protein carbonyls by ethanol-treated cells was significantly increased, whereas that of protein sulfhydryls was significantly decreased. In conclusion, ethanol oxidatively damages pancreatic acinar cells; cerulein stimulation is followed by a lower output of amylase and by a higher release of oxidized proteins by pancreatic acinar cells from ethanol-treated rats. These findings may account for the decreased exocrine function, intraductular plug formation, and protein precipitation in alcoholic pancreatitis.

Assessment of oxidative stress in chronic pancreatitis patients

AIM: To assess the levels of antioxidant capacity and oxidative damage in blood of chronic pancreatitis (CP) patients in comparison with those in healthy control subjects, by using several different analytical techniques.

METHODS: Thirty-five CP patients and 35 healthy control subjects were investigated prospectively with respect to plasma levels of thiols, ferric reducing ability of plasma (FRAP, i.e. antioxidant capacity), levels of protein carbonyls and thiobarbituric acid reactive substances (TBARS). Additionally, we evaluated the production of reactive oxygen species (ROS) in whole blood.

RESULTS: The antioxidative thiols including cysteine, cysteinylglycine and glutathione were significantly lower in CP patients. In addition, the non-enzymatic antioxidant capacity was significantly lower in CP patients, which correlated with the amount of oxidative protein (protein carbonyls) and the extent of lipid damage (TBARS), both were significantly higher in CP patients. The ROS production in whole blood after stimulation with phorbol 12-myritate 13-acetaat, demonstrated a strong tendency to produce more ROS in CP patients.

CONCLUSION: Oxidative stress may contribute to the pathogenesis of chronic pancreatitis by decreasing antioxidant capacity and increasing oxidative damage in CP patients may be a rationale for intervention with antioxidant therapy.

Free radicals and the pancreatic acinar cells: role in physiology and pathology

Reactive oxygen and nitrogen species (ROS and RNS) play an important role in signal transduction and cell injury processes. Nitric oxide synthase (NOS)-the key enzyme producing nitric oxide (NO)-is found in neuronal structures, vascular endothelium and, possibly, in acinar and ductal epithelial cells in the pancreas. NO is known to regulate cell homeostasis, and its effects on the acinar cells are reviewed here. ROS are implicated in the early events within the acinar cells, leading to the development of acute pancreatitis. The available data on ROS/RNS involvement in the apoptotic and necrotic death of pancreatic acinar cells will be discussed.

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

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

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

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

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

NADPH oxidase mediates interleukin-6 expression in cerulein-stimulated pancreatic acinar cells

NADPH oxidase produces a large amount of reactive oxygen species (ROS) mainly in phagocytic cells. ROS are involved in NF-kappaB activation, cytokine expression and thus, pathogenesis of pancreatitis. However, the source of ROS in pancreatic acinar cells has not been clarified. Cerulein rapidly induces acute and edematous form of pancreatitis. We investigated whether pancreatic acinar cells contain NADPH oxidase, and whether NADPH oxidase mediates interleukin-6 (IL-6) in pancreatic acinar AR42J cells stimulated with cerulein. Expression of NADPH oxidase subunits and NADPH oxidase activity were determined in the cells by immunofluorescence staining and lucigenin luminescence, respectively. Oxidant-sensitive nuclear transcription factor NF-kappaB activation was monitored by electrophoretic mobility shift assay. IL-6 expression was determined by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbant assay. NADPH oxidase inhibitor diphenylene iodonium (DPI), antioxidant rebamipide, and antisense oligonucleotides (AS ODNs) for NADPH oxidase subunits p22phox and p47phox were used to determine the involvement of NADPH oxidase in NF-kappaB activation and IL-6 expression in AR42J cells. As a result, pancreatic acinar AR42J cells constitutively express NADPH oxidase subunits p67phox and p47phox in the cytosol and Nox1 and p22phox in the membrane. Cerulein-stimulated NADPH oxidase activity and induced NF-kappaB activation and IL-6 expression in AR42J cells. Treatment of DPI or rebamipide and transfection of AS ODNs for NADPH oxidase subunits suppressed cerulein-induced NF-kappaB activation and IL-6 expression compared to S ODNs. In conclusion, NADPH oxidase may mediate the expression of inflammatory cytokines by stimulating NF-kappaB activation in pancreatic acinar cells during the course of pancreatitis.

Molecular mechanisms of alcoholic pancreatitis

Alcoholic pancreatitis is a major complication of alcohol abuse. Since only a minority of alcoholics develop pancreatitis, there has been a keen interest in identifying the factors that may confer individual susceptibility to the disease. Numerous possibilities have been evaluated including diet, drinking patterns and a range of inherited factors. However, at the present time, no susceptibility factor has been unequivocally identified. In contrast, considerable progress has been made with respect to the constant effects of alcohol on the pancreas. The molecular mechanisms of alcohol-induced pancreatic injury are being increasingly defined with an emphasis, in recent years, on the acinar cell itself as the principal site on ethanol-related damage. It has now been established that the acinar cell is capable of metabolizing alcohol and that the direct toxic effects of alcohol and/or its metabolites on acinar cells may predispose the gland to autodigestive injury in the presence of an appropriate triggering factor. A significant recent development relates to the characterization of pancreatic stellate cells, increasingly implicated in alcoholic pancreatic fibrosis. Here the current concepts regarding the mechanisms/pathways mediating alcohol-induced pancreatic injury are outlined.

Pathogenesis of chronic pancreatitis: an evidence-based review of past theories and recent developments

In the past several decades, four prominent theories of chronic pancreatitis pathogenesis have emerged: the toxic-metabolic theory, the oxidative stress hypothesis, the stone and duct obstruction theory, and the necrosis-fibrosis hypothesis. Although these traditional theories are formulated based on compelling scientific observations, substantial contradictory data also exist for each. Furthermore, the basic premises of some of these theories are directly contradictory. Because of the recent scientific progress in the underlying genetic, cellular, and molecular pathophysiology, there have been substantial advances in the understanding of chronic pancreatitis pathogenesis. This paper will provide an evidence-based review and critique of the traditional pathogenic theories, followed by a discussion of the new advances in pancreatic fibrogenesis. Moreover, we will discuss plausible pathogenic sequences applied to each of the known etiologies.

The dynamics of the oxidant-antioxidant balance in the early phase of human acute biliary pancreatitis

BACKGROUND/AIM

Reactive oxygen species play an important role in the pathogenesis of acute pancreatitis (AP) in animal models. Data on the oxidant-antioxidant balance in humans are scanty. The present study was undertaken to evaluate the dynamics of changes in the oxidant-antioxidant balance in the early phase of human AP.

METHODS

74 consecutive patients with acute biliary pancreatitis (16 with severe, 58 with mild pancreatitis), treated endoscopically, were included in the study. Serum concentrations of sulfhydryl groups (SH; main nonenzymatic antioxidant; 73 patients) and thiobarbituric acid reactive substances (TBARS; markers of reactive oxygen species-mediated tissue damage; 56 patients) were determined on admission and on each of 10 successive days. The analysis comprised the comparison of results in patients with mild and severe outcome of pancreatitis.

RESULTS

Serum SH dropped by 27%, reaching the trough level on day 4 of hospitalization, whereas serum TBARS rose by 28%, reaching a peak 1 day later. Neither SH nor TBARS returned to initial values at the end of observation. The most dynamic changes in both SH and TBARS concentrations occurred in the first 3 days of hospitalization. The changes were significantly greater in patients with complicated pancreatitis in comparison to patients with mild disease, and were most pronounced in patients who developed infected pancreatic necrosis and who subsequently died.

CONCLUSIONS

The oxidant-antioxidant balance changes rapidly in the early phase of human AP, confirming the role of oxidative stress in the pathogenesis of AP. The degree of changes correlates with the clinical severity of pancreatitis.

Nutritional supplements and alternative medicine

PURPOSE OF REVIEW

A major health care trend in the last decade has been the increased use of complementary and alternative medicine and nutritional supplements. Indeed, we now have Physician's Desk References for both herbal therapies and dietary supplements. A large amount of out-of-pocket dollars are spent on complementary and alternative medicine each year in the United States, and complementary and alternative medicine users believe strongly in the efficacy of their treatments.

RECENT FINDINGS

In the area of inflammatory bowel disease, probiotics appear to be a highly promising form of therapy. In acute pancreatitis, enteral nutrition has been shown to be safe and effective. Peppermint oil is one of the most widely used complementary and alternative medicine therapies for irritable bowel syndrome. Antioxidants are increasingly used in liver disease, especially agents involved in methionine metabolism. Both S-adenosylmethionine and betaine have shown efficacy in animal models of alcoholic liver disease, and "knockout" mice that develop S-adenosylmethionine deficiency also develop steatohepatitis. Thus, there is great interest in these complementary and alternative medicine agents in both alcoholic liver disease and nonalcoholic steatohepatitis. There are also important safety issues related to complementary and alternative medicine. Deaths of well-known athletes have highlighted the risks of ephedra, and some research suggests that complementary and alternative medicine agents are a major cause of fulminant liver failure necessitating liver transplantation.

SUMMARY

Thus, physicians must be aware not only of the potential therapeutic benefits of complementary and alternative medicine agents and nutritional supplements, but also their potential risks, including toxicity and drug interactions.

Role of alcohol metabolism in alcoholic pancreatitis

Metabolism of ethanol by acinar and other pancreatic cells and the consequent generation of toxic metabolites are postulated to play an important role in the development of alcohol-related acute and chronic pancreatic injury. Studies using cultured pancreatic acinar cells and isolated pancreatic acini have established that (i) the pancreas can metabolize ethanol via the oxidative pathway involving the enzymes alcohol dehydrogenase (ADH) and possibly cytochrome P4502E1 (although the role of the latter remains to be fully delineated) as well as the nonoxidative pathway [involving fatty acid ethyl ester (FAEE) synthases] and (ii) the oxidative pathway (which generates acetaldehyde) is quantitatively greater than the nonoxidative pathway, which yields FAEEs. Most recently, pancreatic stellate cells (PSCs) (implicated in pancreatic fibrogenesis) have been reported to exhibit ADH activity, suggesting that the capacity of the pancreas to metabolize ethanol may reside not only in parenchymal (acinar) cells but also in nonparenchymal cells. Polymorphisms/mutations of ethanol metabolizing enzymes have been examined to determine whether they may confer individual susceptibility to alcoholic pancreatitis. However, no association has been demonstrated between ADH and CYP2E1 polymorphisms and the predisposition to alcoholic pancreatitis. Other candidate factors that remain to be studied include polymorphisms of FAEE synthetic enzymes and proteins relevant to antioxidant pathways in the cell. Injury to the pancreas due to its capacity to metabolize ethanol may be mediated by direct effects of both acetaldehyde and FAEEs and by alterations induced within the cells during ethanol metabolism, such as changes in the intracellular redox state and the generation of oxidant stress.

Oxidative stress induces nuclear loss of DNA repair proteins Ku70 and Ku80 and apoptosis in pancreatic acinar AR42J cells

Cell death linked to oxidative DNA damage has been implicated in acute pancreatitis. The severe DNA damage, which is beyond the capacity of the DNA repair proteins, triggers apoptosis. It has been hypothesized that oxidative stress may induce a decrease in the Ku70 and Ku80 levels and apoptosis in pancreatic acinar cells. In this study, it was found that oxidative stress caused by glucose oxidase (GO) acting on beta-d-glucose, glucose/glucose oxidase (G/GO), induced slight changes in cytoplasmic Ku70 and Ku80 but drastically induced a decrease in nuclear Ku70 and Ku80 both time- and concentration-dependently in AR42J cells. G/GO induced apoptosis determined by poly(ADP-ribose) polymerase cleavage, an increase in expression of p53 and Bax, and a decrease in Bcl-2 expression. G/GO-induced apoptosis was in parallel with the loss of nuclear Ku proteins in AR42J cells. Caspase-3 inhibitor prevented G/GO-induced nuclear Ku loss and cell death. G/GO did not induce apoptosis in the cells transfected with either the Ku70 or Ku80 expression gene but increased apoptosis in those transfected with the Ku dominant negative mutant. Pulse and pulse-chase results show that G/GO induced Ku70 and Ku80 syntheses, even though Ku70 and Ku80 were degraded both in cytoplasm and nucleus. G/GO-induced decrease in Ku binding to importin alpha and importin beta reflects possible modification of nuclear import of Ku proteins. The importin beta level was not changed by G/GO. These results demonstrate that nuclear decrease in Ku70 and Ku80 may result from the decrease in Ku binding to nuclear transporter importins and the degradation of Ku proteins. The nuclear loss of Ku proteins may underlie the mechanism of apoptosis in pancreatic acinar cells after oxidative stress.

Effects of ethanol and folic acid consumption during pregnancy and lactation on basal enzymatic secretion in the duodenal juice of offspring rats

OBJECTIVES

Studies on duodenal juice enzyme activities were carried out on suckling Wistar rats born to dams given ethanol during gestation and suckling. The results were compared with offspring of dams given diets containing no ethanol. Comparisons were also made with offspring of dams given ethanol and folic acid supplementation to observe whether a folate supplement could sufficiently reverse the negative effect of ethanol consumption.

METHODS

The dams were fed increased amounts of ethanol (5% to 20%, vol/vol) in tap water for 4 wk. The maximum quantity, 20% ethanol, was given to the dams during pregnancy and lactation. Offspring animals were randomized into three groups: control (CG), ethanol treated (EG), and ethanol plus folic acid (EFG).

RESULTS

Body weight at birth and at 21 d after birth and pancreatic weight were lower in offspring after ethanol treatment. Folic acid supplement increased these parameters in the EFG. Under basal conditions, decreases in amylase, lipase, and chymotrypsin activities in the duodenal juice after ethanol treatment were detected. Serum and urine amylase activities also decreased in the EG and EFG. These changes were different in the ethanol-treated progenitors. In these progenitors, ethanol treatment increased serum amylase levels. In the offspring, amylase activities in the EFG decreased with respect to the CG; however, an increase in the EG was observed. In dams the folic acid supplement did not significantly alter the serum amylase activities. Lipase and chymotrypsin activities in the EFG were similar to those in the EG. An increase of serum and urine amylase in the EFG with respect to the EG was found.

CONCLUSIONS

Our findings indicated that, under basal conditions, ethanol treatment during gestation and lactation negatively affects the digestive function in offspring. The effects of ethanol were slightly attenuated in rats supplemented with folic acid for amylase activities. Although extrapolation from animal studies can be tenuous, the present findings may explain the use of folic acid in the prevention of damage induced by ethanol to increase the amylase levels to physiologic concentrations.

Suppression of cerulein-induced cytokine expression by antioxidants in pancreatic acinar cells

Reactive oxygen species (ROS) has been considered to be an important regulator in the development and pathogenesis of pancreatitis and an activator of the transcription factor, nuclear factor-kappaB (NF-kappaB), regulating inflammatory cytokine gene expression. NF-kappaB activation was demonstrated in cerulein pancreatitis, which rapidly induces an acute, edematous form of pancreatitis. This study aimed to investigate whether cerulein induced ROS generation, lipid peroxide and hydrogen peroxide production, NF-kappaB activation, and expression of cytokines (IL-1beta, IL-6) in pancreatic acinar cells. An additional aim was to establish whether these alterations were inhibited by antioxidants such as glutathione, superoxide dismutase, and catalase and an inhibitor of NF-kappaB activation, pyrrolidine dithiocarbamate (PDTC). To determine the possible interactions of the antioxidants and PDTC with cerulein-induced signaling, Ca2+ signal and amylase release were monitored in the pancreatic acinar cells treated with cerulein in the presence or absence of either the antioxidants or PDTC. The results showed that cerulein generated ROS and increased lipid peroxide and hydrogen peroxide production in the acinar cells, as determined by dichlorofluorescein diacetate dye. This resulted in NF-kappaB activation and the induction of cytokine gene expression in the cells. The cerulein-induced NF-kappaB activation was in parallel to IkappaBalpha degradation. Cerulein also induced Ca2+ signals and amylase release in acinar cells. Both antioxidants (glutathione, superoxide dismutase, catalase) and PDTC inhibited the cerulein-induced, oxidant-mediated alterations but did not affect the cerulein-evoked Ca2+ signals and amylase release in acinar cells. In conclusion, ROS, generated by cerulein, activates NF-kappaB, resulting in the up-regulation of inflammatory cytokine gene expression in acinar cells. NF-kappaB inhibition by scavenging ROS might alleviate the inflammatory response in pancreatic acinar cells by suppressing cytokine gene expression.

Xanthine oxidase-derived oxygen radicals play significant roles in the development of chronic pancreatitis in WBN/Kob rats

BACKGROUND

Although oxygen-derived free radicals are known to play a role in cell injury and DNA alterations, the role of active oxidants in chronic pancreatitis has not been fully elucidated. Using WBN/Kob rats, which spontaneously develop chronic pancreatitis-like lesions, we investigated whether xanthine oxidase (XOD)-derived oxygen radicals are involved in pancreatic tissue injury.

METHODS

WBN/Kob rats were fed a control or a tungsten diet. The latter depletes XOD activity. Histologic al changes, glutathione (GSH) content and XOD and superoxide dismutase (SOD) activities were determined in pancreatic tissue. Pancreatic 8-hydroxy-deoxyguanosine (8-OH-dG) levels and lithostathine mRNA were also examined.

RESULTS

In WBN/Kob rats, parenchymal destruction and fibrosis developed at approximately 12 weeks of age and progressed with each month. The activity of XOD was significantly higher in the early period (8-12 weeks), whereas the levels of GSH and SOD decreased after 16 weeks. Levels of 8-OH-dG in WBN/Kob rats were significantly elevated at 16 weeks. Lithostathine mRNA levels started to increase at 8 weeks, but were suppressed at 16 weeks. The tungsten diet significantly attenuated the histological changes in WBN/Kob rats. The increase in pancreatic XOD activity and 8-OH-dG content in WBN/Kob rats was significantly inhibited by the tungsten diet and lithostathine mRNA levels remained high at 16 weeks.

CONCLUSION

These results suggest that oxygen radicals generated by XOD play an important role in oxidative DNA damage and the development of chronic pancreatic injury.

Linkage of oxidative and nonoxidative ethanol metabolism in the pancreas and toxicity of nonoxidative ethanol metabolites for pancreatic acinar cells

BACKGROUND

Alcohol abuse is a major cause of pancreatic damage. Recent experimental evidence suggests that fatty acid ethyl esters (FAEE), nonoxidative ethanol metabolites, injure pancreatic acinar cells. Linkage between oxidative and nonoxidative metabolism of ethanol in the pancreas may contribute to increased FAEE levels.

METHODS

To study the association between oxidative and nonoxidative ethanol metabolism, FAEE concentration and FAEE synthase activity in rat pancreatic and liver homogenates incubated with ethanol were evaluated with and without inhibitors of oxidative ethanol metabolism. For toxicity studies, trypsinogen activation peptide synthesis as a measure of pancreatic cell injury was quantitated in unstimulated and cerulein-stimulated isolated pancreatic acinar cells incubated with ethanol or FAEE.

RESULTS

Inhibition of oxidative ethanol metabolism results in a 2- to 3-fold increase in nonoxidative ethanol metabolism to FAEE in pancreas and in liver. Both ethanol and FAEE induce increased intracellular trypsinogen activation by more than 50% in the presence of physiologic concentrations of cerulein in vitro.

CONCLUSIONS

These findings demonstrate that the inhibition of oxidative ethanol metabolism results in an increase in flux through the nonoxidative pathway and support the proposition that alcohol-induced pancreatic injury is mediated at least in part by FAEE, which are important products of pancreatic ethanol metabolism.

Antifibrotic effect of the herbal medicine Saiko-keishi-to (TJ-10) on chronic pancreatitis in the WBN/Kob rat

Chronic pancreatitis is characterized by fibrosis. We reported an anti-inflammatory effect of the herbal medicine Saiko-keishi-to (TJ-10) on chronic pancreatitis. This study aimed to elucidate the antifibrotic effect of TJ-10. Four-week-old male WBN/Kob rats were fed a special pellet diet (MB-3) with or without TJ-10 (80 mg/100 g body weight) for 20 weeks. Pancreata were histopathologically examined at every 4 weeks, and the expression of fibrosis-related factors such as transforming growth factor beta1 (TGF-beta1), fibronectin (FN), alpha-smooth muscle actin (alpha-SMA), and type III collagen was analyzed. In untreated WBN/Kob rats, chronic pancreatitis developed at 12 weeks and progressed with marked fibrosis at 16 weeks, and the expression of TGF-beta1 and FN peaked at 12 weeks. However, in the TJ-10-treated rats, the rate of pancreatic fibrosis and the expression of TGF-beta1, FN, alpha-SMA, and type III collagen at 12 and 16 weeks decreased significantly compared to those in the untreated rats. These results suggest that TJ-10 inhibits the pancreatic fibrosis by the suppression of TGF-beta1 expression.

Xenobiotic metabolism, oxidant stress and chronic pancreatitis. Focus on glutathione

Chronic pancreatitis, although relatively rare in the Western World, is common in certain tropical zones where staple crops such as cassava are rich in cyanogenic glycosides. This paper reviews the evidence for a cyanide connection, with reference to experimental studies using another plant nitrile, crambene; and then examines the hypothesis that chronic pancreatitis represents a manifestation of uncoordinated detoxification reactions between pancreatic cytochrome P450 mono-oxygenases and phase II conjugating enzymes, resulting in the irreversible consumption of glutathione in the acinar cell. The conclusion is that the central role of disrupted pancreatic glutathione status, as a result of 'xenobiotic stress', in the evolution of chronic pancreatitis cannot be overestimated. This position contrasts with that in acute pancreatitis, in which glutathione depletion has a pivotal role too, but occurs as a result of 'stress' from reactive oxygen species.

A framework for the aetiogenesis of chronic pancreatitis

The traditional ductal model for the development of chronic pancreatitis leaves many questions unanswered and it has not facilitated management. An alternate philosophy centres on the acinar cell as the site of mounting oxidant stress, usually as a result of steady exposure to xenobiotics that induce cytochrome P450 mono-oxygenases while depleting glutathione: ductal changes are regarded as secondary, disease-compounding manifestations of the oxidant environment. Within this framework each burst of oxidant stress jeopardises exocytosis, to trigger an attack of pancreatitis by interfering with the methionine-to-glutathione transsulphuration pathway, which interacts closely with ascorbate and selenium. The resulting diversion of free radical oxidation products into the pancreatic interstitium causes mast cells to degranulate, thereby provoking inflammation, the activation of nociceptive axon reflexes, and profibrotic interactions.

Pancreatitis in Soweto, South Africa. Focus on alcohol-related disease

Both acute pancreatitis and chronic pancreatitis now appear to be endemic at Soweto, South Africa, and they carry a substantial toll in terms of morbidity and mortality. Case-control studies identified the same three environmental factors in each disease, namely, heavy alcohol consumption, marked exposure to occupational chemicals and low intake of fruit (a major source of vitamin C). This congruity, and parallel trends on blood biochemical analysis indicating heightened free radical activity coupled with poor antioxidant status, suggest that the two diseases may be part of a pathobiological spectrum that is linked by pancreatic oxidant stress. Further, asymptomatic chronic alcoholics had plasma glutathione concentrations that were midway between the values in non-alcoholic controls and patients with chronic pancreatitis, being significantly different from each. And, finally, apparently healthy Sowetans were actually in a state of oxidant stress that was tied in with their very poor vitamin C status, and lower serum selenium concentrations than in the UK. These data, and evidence that both antioxidants mitigate against alcoholic toxicity in experimental studies, may offer scope for disease prophylaxis in this unprivileged community.

Chronic pancreatitis at Manchester, UK. Focus on antioxidant therapy

The Manchester 'oxidant stress' hypothesis for the development of pancreatitis accommodates published information on both chronic pancreatitis and acute pancreatitis. Oxidant stress, mainly from reactive xenobiotic metabolites, is perceived as the pivotal pre-morbid problem in chronic pancreatitis and, by depleting glutathione, targets the exocytosis mechanism of the pancreatic acinar cell. Inhalation exposure to petrochemical products is identified as an independent risk factor in patients at Manchester Royal Infirmary, where some 50% of patients referred have non-alcoholic disease. This paper describes the development of antioxidant therapy, using supplements of methionine, vitamin C and selenium, and its validation in a placebo-controlled trial, followed by a retrospective cross-sectional study in 94 consecutive patients for an average of 30 months. Antioxidant therapy emerges as a safe and effective medical alternative to surgery for painful chronic pancreatitis.

Chronic ethanol administration induces oxidative alterations and functional impairment of pancreatic mitochondria in the rat

Pancreas is known to be vulnerable to ethanol (ETOH) at high doses, but little is known about the effect of lower doses. Therefore, in this study, the levels of glutathione (GSH), sulfhydryl proteins (P-SH), carbonyl proteins, malondialdehyde (MDA), and adenosine triphosphate (ATP) production were determined in the pancreatic tissue and mitochondria of rats fed for 8 weeks with 3% ETOH. ETOH decreased the pancreatic pool of ATP, while GSH and P-SH also decreased in mitochondria. MDA concentrations increased both in the pancreas and mitochondria, while carbonyl proteins increased only in mitochondria. Pancreatic cells of ETOH-treated rats were frequently affected by cytoplasmic vacuolization and swelling; these alterations were often associated with ductular dilatation. In conclusion, ETOH produces oxidative and morphologic alterations in the pancreas of the rat, including impairment of mitochondria. These effects may represent basic mechanisms of ETOH-induced pancreatic injury.

The antioxidant profiles of patients with recurrent acute and chronic pancreatitis

OBJECTIVE

It has been suggested that patients with chronic pancreatitis have antioxidant deficiencies. It is unclear whether these antioxidant deficiencies also occur in patients with recurrent acute pancreatitis and whether this condition represents an intermediate state between normality and chronic pancreatitis. The aim of this study was to determine the antioxidant profiles of patients with pancreatitis (recurrent acute and chronic) and to compare their profiles with a control population.

METHODS

The antioxidant profiles of patients with chronic pancreatitis (n = 27) and recurrent acute pancreatitis (n = 11) were determined and compared with the antioxidant profiles of control subjects (n = 19). The following parameters were measured in blood: trace elements (selenium, copper, zinc), vitamins A and E, and carotenoids (alpha-carotene, beta-carotene, xanthine, beta-cryptoxanthine, lycopene).

RESULTS

Patients with chronic pancreatitis had significantly lower plasma concentrations of selenium, vitamin A, vitamin E, beta-carotene, xanthine, beta-cryptoxanthine, and lycopene compared with both control subjects and patients with recurrent acute pancreatitis (p < 0.05). There were no significant differences between the antioxidant profiles of patients with chronic pancreatitis due to alcohol excess and patients with idiopathic chronic pancreatitis, or between the antioxidant profiles of patients with recurrent acute pancreatitis and control subjects.

CONCLUSIONS

Patients with chronic pancreatitis had evidence of multiple antioxidant deficiencies. The antioxidant profiles of patients with recurrent acute pancreatitis did not differ from those of control subjects, discounting the hypothesis that recurrent acute pancreatitis represents an intermediate state between normality and chronic pancreatitis.

Alcohol-induced pancreatic oxidative stress: protection by phospholipid repletion

Oxidative stress is considered to be a forerunner of pancreatitis. Since we had found polyenylphosphatidylcholine, a mixture of polyunsaturated phosphatidylcholines extracted from soybeans, to protect against hepatic oxidative stress, we now tested its effects on the pancreas. Sprague-Dawley rats were pair-fed for two months nutritionally adequate liquid diet containing ethanol (36% of energy) or isocaloric carbohydrate, with either polyenylphosphatidylcholine (3 g/1000 kcal) or safflower oil, with or without 5 g/1000 kcal carbonyl iron. Parameters of oxidative stress (F2-isoprostanes, 4-hydroxynonenal, reduced glutathione), ubiquinol-10, ubiquinol-9 and vitamin E, as well as phosphatidylcholine species, were assessed by GC/MS and/or HPLC. Alcohol feeding increased pancreatic 4-hydroxynonenal three-fold, F2-isoprostanes and ubiquinol-9 by more than 70%, whereas it decreased total phospholipids, several phosphatidylcholine species, ubiquinol-10 and glutathione, especially in iron fed rats. Polyenylphosphatidylcholine prevented the rise in 4-hydroxynonenal and F2-isoprostanes, the decrease in dilinoleoylphosphatidylcholine and oleoyllinoleoylphosphatidylcholine and opposed the alcohol-induced decrease of glutathione; alpha-tocopherol remained unchanged. Iron had no significant effect except for decreasing ubiquinol-10 in the pancreas and increasing aminotransferases in the plasma. Thus, the alcohol-induced oxidative stress in the pancreas was shown to be prevented by polyenylphosphatidylcholine which may act, in part, by correcting the depletion of several phosphatidylcholine species.

Alcohol and the pancreas

Alcoholic pancreatitis is a major, often lethal complication of alcohol abuse. Until recently it was generally accepted that alcoholic pancreatitis was a chronic disease from the outset. However, there is now emerging evidence in favour of the necrosis-fibrosis hypothesis that alcoholic pancreatitis begins as an acute process and that repeated acute attacks lead to chronic pancreatitis, resulting in exocrine and endocrine failure. Over the past 10-15 years, the focus of research into the pathogenesis of alcoholic pancreatitis has shifted from possible sphincteric and ductular abnormalities to the acinar cell itself which has increasingly been implicated as the initial site of injury. Recent studies have shown that the acinar cell can metabolize alcohol at rates comparable to those observed in hepatocytes. In addition, it has been demonstrated that alcohol and its metabolites exert direct effects on the pancreatic acinar cell which may promote premature digestive enzyme activation and oxidant stress. The challenge remains to identify predisposing and triggering factors in this disease.

Cu/Zn-SOD in human pancreatic tissue and pancreatic juice

CONCLUSION

Cu/Zn-SOD is present in pancreatic juice and tissue. Immunohistochemical studies reveal a localization of this enzyme in islet, duct, and centroacinar cells, but to a much lower extent in pancreatic acinar cells.

BACKGROUND

It is generally accepted that oxygen radicals are involved in the pathogenesis of acute and chronic pancreatitis. An imbalance of radical-generating and radical-scavenging processes is thought to lead to the damage of pancreatic acinar cells that initiate the autodigestion of the whole organ.

METHODS

We investigated the distribution pattern of the cytosolic radical-scavenging enzyme, copper/zinc-superoxide dismutase (Cu/Zn-SOD), in pancreatic juice and tissue. In patients with chronic pancreatitis or pancreatic malignancies, Cu-Zn-SOD was quantitated in different fractions of pancreatic juice by means of an enzyme immunoassay using two Cu/Zn-SOD-specific monoclonal antibodies. Cryostat or paraffin sections of pancreatic tissue were analyzed by immunohistochemical techniques.

RESULTS

We found this enzyme to be present in the first secretin-triggered fraction of endoscopically obtained pancreatic juice in concentrations similar to serum. In contrast, after cholecystokinin stimulation, only low levels could be found in pancreatic juice, indicating that this enzyme is not actively secreted. Interestingly, pancreatic juice of patients with chronic pancreatitis or pancreas tumor contained higher levels (25-29 ng/mL) of Cu/Zn-SOD than juice of controls without pancreatic diseases (15 ng/mL). Immunohistochemical studies of Cu/Zn-SOD in pancreatic tissue revealed a more intense staining of duct cells, islet cells, and centroacinar cells, whereas acinar cells showed almost no staining for Cu/Zn-SOD.

A pilot study of antioxidant intake in patients with cholesterol gallstones

Whereas macronutrient intake has been extensively investigated in an attempt to unravel the pathogenesis of human cholesterol gallstones, theoretical considerations and animal models suggest that deficits in micronutrient antioxidants may be more relevant. We report a pilot study of this aspect. The plan was to obtain 7-d weighed food inventories over a 6-mo period from equal numbers of patients who had not consciously changed their diets, patients who were on low-fat diets and age- and gender-matched controls. Food tables would be used to derive daily intakes of 16 known antioxidants, essential amino acids, and essential fatty acids. Under-reporting of food intake, a recognized drawback of this dietary method, would be sought retrospectively by reference to a key publication giving minimum cut-off limits for ratios of energy intakes to basal metabolic rates. There were 18 pairs for study. Analysis of data for the 9 pairs involving patients on their normal diets showed no differences in the intakes of energy macronutrients, and cholesterol, but the patients ingested lower amounts of 10 among 16 antioxidants (P < 0.05 for methionine, alpha-tocopherol, manganese, and vitamin D; 0.05 < P < 0.10 for cysteine, beta-carotene, vitamin C, selenium, zinc, and phosphorus). Both subsets of patients ingested lower amounts of linoleic acid (diet unchanged P = 0.009, changed P = 0.026) and several essential amino acids than did matched controls. Institution of a low-fat diet caused the expected fall in intakes of energy and saturated fatty acids such that the deficit in alpha-tocopherol was amplified, but substitution of fruit and vegetables by the patients resulted in a fortuitous increase in vitamin C, beta-carotene, and manganese intake. Retrospective analysis confirmed under-reporting of food intake by all four subsets of subjects but there was no significant difference in the mean ratio of energy intake to estimated basal metabolic rate in the subset of patients who had not consciously altered their diets and the subset of matched controls. Furthermore, the lower daily intake of alpha-tocopherol and linoleic acid by these patients persisted when results were expressed relative to total fat consumption. The results support the hypothesis that insufficiency of dietary antioxidants, particularly alpha-tocopherol, may be germane to human gallstone disease; they also suggest that low intakes of linoleic acid and essential amino acids may be relevant. Because of the small sample sizes, however, these deductions should be regarded as tentative, pending confirmation by biochemical analysis of blood and especially of hepatic bile.

A pilot study of blood antioxidant and free radical marker profiles in patients awaiting coronary artery bypass grafting

Coronary artery bypass grafting (CABG) carries a high risk of acute pancreatitis. We report a pilot study to investigate whether pre-existing oxidative stress might underlie this susceptibility, in that a burst of free radical activity not only accompanies the reperfusion stage of CABG but seems to be a pivotal step in the pathogenesis of pancreatitis. Samples of peripheral venous blood were obtained on the morning of surgery from 8 consecutive patients (age, median and range, 62, 35-70 years) with > 75% stenosis in at least three coronary vessels and a further 8 (64, 49-70 years) who had received 1200 mg allopurinol in divided doses in the previous 48 h: the results were compared with profiles of 8 healthy controls (56, 50-60 years) with normal exercise ECG. None of the patients or controls currently smoked cigarettes and the majority drank alcohol on a social basis. Compared with controls, untreated patients had lower levels of glutathione (P < 0.001) and ascorbate (P < 0.05) in plasma, alpha-tocopherol (vitamin E as molar ratio of cholesterol, P < 0.025 and beta-carotene (P < 0.05) in serum. There was no difference in serum selenium levels, but values in patients and controls were lower than in younger controls from this area (P < 0.02). Samples from the patients contained higher concentrations of lipid peroxides than control samples (P < 0.25) but there was no evidence of excessive isomerisation of linoleic acid or oxidation of ascorbate and erythrocytes showed normal ATP and energy charge with no increase in membrane lipid peroxidisability. Treatment with allopurinol did not alter this pattern, such that the ratio of oxidised to total glutathione in plasma was higher among the 16 patients than 8 controls (P < 0.025). Habitually inadequate intakes are the best explanation for the patients' deficits in aqueous phase antioxidants; prescribed low cholesterol diets would exacerbate any prior insufficiency of lipid-phase antioxidants. Correction of these deficits during the months leading up to surgery should reduce the risk of CABG-induced acute pancreatitis.

Acute ethanol administration induces oxidative changes in rat pancreatic tissue

BACKGROUND

There is mounting clinical evidence that ethanol toxicity to the pancreas is linked with glutathione depletion from oxidative stress but there is not experimental proof that this occurs.

AIMS AND METHODS

The effect of acute ethanol ingestion (4 g/kg) on the pancreatic content of reduced (GSH) and oxidised (GSSG) glutathione, malondialdehyde (MDA), and carbonyl proteins were therefore studied in the rat.

RESULTS

Ethanol caused a significant reduction in GSH (p < 0.02) and an increase in GSSG (p < 0.005), MDA (p < 0.05), and carbonyl proteins (p < 0.05) in the rat pancreas. The GSH/GSSG ratios were significantly decreased after ethanol, especially in rats pretreated with diethylmaleate (DEM), a GSH blocker. Administration of ethanol after DEM further increased the rate of lipid and protein oxidation. Pretreatment with cyanamide (an inhibitor of aldehyde dehydrogenase) but not with 4-methylpyrazole (an alcohol dehydrogenase inhibitor) caused higher production of GSSG and MDA.

CONCLUSIONS

These findings indicate that acute ethanol reduces the pancreatic content of GSH, which seems to be protective against ethanol toxicity, since its depletion is accompanied by increased oxidative damage to cell structures. The further increase of lipid peroxidation and GSSG production in the presence of cyanamide suggests that acetaldehyde might be responsible for the oxidative changes that occur in pancreatic cells after ethanol administration.

Oxidative stress in rodent closed duodenal loop pancreatitis

CONCLUSION

Production of excited oxygen species is earlier in the liver than in the pancreas and could contribute to damage in a reflux model. Treatment with SOD could attenuate 59% light emission in pancreas, but did not modify serum enzyme levels or pancreatic edema, resulting as an insufficient isolated therapy. Unexpectedly, it was found an increased plasma antioxidant capacity that was related to total bilirubin levels, and declined at late stages probably denoting other circulating antioxidant consumption.

BACKGROUND

Oxidative stress has been shown to play a role in different models of acute pancreatitis, although it has not been studied in the severe necrohemorrhagic model produced by closed duodenal loop pancreatitis.

METHODS

We studied Sprague Dawley female rats in two groups: a closed duodenal loop pancreatitis group and a control, sham-operated group. In order to evidence the oxygen excited species production, in situ spontaneous chemiluminescence from living and naturally perfused pancreas and liver was measured at 0, 0.5, 1.5, 3, 6, 12, and 24 h after the duodenal ligature. Blood pancreatic amylase and aminotransferases levels were determined as expression of tissue damage in pancreas and liver. At the same time, plasma antioxidant capacity was measured by the peroxyl radical trapping capability of plasma samples compared to that of Trolox (synthetic analog of vitamin E), and results are expressed as Trolox equivalence. Bovine superoxide dismutase (SOD) was administered to attenuate oxygen free radicals activity at the beginning of the peroxidation chain and also as a therapeutic tool.

RESULTS

The experimental procedure induced a severe pancreatitis, as evidenced by pancreatic enzymes that rose markedly in the early hours of disease and remained heightened throughout the experiment. The results show early light emission from the liver at 3 h and peak levels at 12 h, whereas in the pancreas, luminescence increased at 6 h and doubled later at 12 h, both returning to control levels at 24 h.

A radical view of gallstone aetiogenesis

It is proposed that gallstones stem from insufficiency of micronutrient antioxidants relative to the load of oxidants and/or oxidation-prone substrates within hepatocytes in such a way that ancillary hepatobiliary resources, including bilirubin with lactoferrin and mucin, are mobilized to combat oxidative stress but inadvertently promote lithogenesis. Aberrant activities of hepatic cytochrome P450 mono-oxygenases and of haem oxygenase are integral to this template, because differential inhibition or activation of these enzymes would help to rationalize the spectrum of human gallstone composition and also the different outcomes when animals are fed the same lithogenic diets. The hypothesis is based on a decade of work on another lithogenic disease, chronic pancreatitis. It accommodates observations on human and experimental gallstones, it is testable and, as shown by studies of chronic pancreatitis, has implications for primary disease prevention.