Specific interaction of pancreatic elastase and leucocytes to produce oxygen radicals and its implication in pancreatitis

Circulating Biomarkers Involved in the Development of and Progression to Chronic Pancreatitis-A Literature Review

Chronic pancreatitis (CP) is the end-stage of continuous inflammation and fibrosis in the pancreas evolving from acute- to recurrent acute-, early, and, finally, end-stage CP. Currently, prevention is the only way to reduce disease burden. In this setting, early detection is of great importance. Due to the anatomy and risks associated with direct sampling from pancreatic tissue, most of our information on the human pancreas arises from circulating biomarkers thought to be involved in pancreatic pathophysiology or injury. The present review provides the status of circulating biomarkers involved in the development of and progression to CP.

Circulating monocytes in acute pancreatitis

Acute pancreatitis is a common gastrointestinal disease characterized by inflammation of the exocrine pancreas and manifesting itself through acute onset of abdominal pain. It is frequently associated with organ failure, pancreatic necrosis, and death. Mounting evidence describes monocytes - phagocytic, antigen presenting, and regulatory cells of the innate immune system - as key contributors and regulators of the inflammatory response and subsequent organ failure in acute pancreatitis. This review highlights the recent advances of dynamic change of numbers, phenotypes, and functions of circulating monocytes as well as their underling regulatory mechanisms with a special focus on the role of lipid modulation during acute pancreatitis.

Single-Cell Transcriptome Analysis Reveals the Role of Pancreatic Secretome in COVID-19 Associated Multi-organ Dysfunctions

The SARS-CoV-2 infection affects the lungs, heart, kidney, intestine, olfactory epithelia, liver, and pancreas and brings forward multi-organ dysfunctions (MODs). However, mechanistic details of SARS-CoV-2-induced MODs are unclear. Here, we have investigated the role of pancreatic secretory proteins to mechanistically link COVID-19 with MODs using single-cell transcriptome analysis. Secretory proteins were identified using the Human Protein Atlas. Gene ontology, pathway, and disease enrichment analyses were used to highlight the role of upregulated pancreatic secretory proteins (secretome). We show that SARS-CoV-2 infection shifts the expression profile of pancreatic endocrine cells to acinar and ductal cell-specific profiles, resulting in increased expression of acinar and ductal cell-specific genes. Among all the secretory proteins, the upregulated expression of IL1B, AGT, ALB, SPP1, CRP, SERPINA1, C3, TFRC, TNFSF10, and MIF was mainly associated with disease of diverse organs. Extensive literature and experimental evidence are used to validate the association of the upregulated pancreatic secretome with the coagulation cascade, complement activation, renin-angiotensinogen system dysregulation, endothelial cell injury and thrombosis, immune system dysregulation, and fibrosis. Our finding suggests the influence of an upregulated secretome on multi-organ systems such as nervous, cardiovascular, immune, digestive, and urogenital systems. Our study provides evidence that an upregulated pancreatic secretome is a possible cause of SARS-CoV-2-induced MODs. This finding may have a significant impact on the clinical setting regarding the prevention of SARS-CoV-2-induced MODs.

Significance of radiology in the diagnosis and management of ruptured left gastric artery aneurysm associated with acute pancreatitis: Case report

RATIONALE

Left gastric artery aneurysms are very rare which progresses into hemorrhagic shock and diagnosis is very challenging particularly in patients with acute pancreatitis and cholecystitis whose vitals become unstable suddenly.

PATIENT CONCERNS

A 72-year-old female has presented with severe progressing abdominal pain was treated with total parenteral nutrition for acute pancreatitis based on preliminary work up, but suddenly became unstable with dropping vitals over the ensuing 48 hours. Physical examination has a positive Murphy sign and appeared lethargic. She has no past history of any chronic systemic illness or malignancy.

DIAGNOSES

Ruptured left gastric artery aneurysm and left hepatic artery aneurysm with intraperitoneal hemorrhage associated with acute pancreatitis and cholecystitis.

INTERVENTIONS

Emergency interventional surgery was performed to embolize both the aneurysms and the giant aneurysmal sac of the left gastric artery was secured with a micrometallic occluding coil which eventually controlled the active hemorrhage.

OUTCOMES

The patient became stable and was discharged after 15 days without any recurrence or complications during the 6-month follow-up.

LESSONS

This case is a peculiar example of a missed diagnosis of left gastric artery aneurysm associated with acute pancreatitis and cholecystitis with deteriorating clinical condition. Exhaustive radiological investigations are necessary for early diagnosis correlating with presenting clinical situations. Radiologists should be familiar with the challenges in diagnosis and management.

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

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

Tempol, a Membrane-Permeable Radical Scavenger, Exhibits Anti-Inflammatory and Cardioprotective Effects in the Cerulein-Induced Pancreatitis Rat Model

To date, it remains unclear whether mild form of acute pancreatitis (AP) may cause myocardial damage which may be asymptomatic for a long time. Pathogenesis of AP-related cardiac injury may be attributed in part to ROS/RNS overproduction. The aim of the present study was to evaluate the oxidative stress changes in both the pancreas and the heart and to estimate the protective effects of 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine (tempol) at the early phase of AP. Cerulein-induced AP led to the development of acute edematous pancreatitis with a significant decrease in the level of sulfhydryl (–SH) groups (oxidation marker) both in heart and in pancreatic tissues as well as a substantial increase in plasma creatine kinase isoenzyme (CK-MB) activity (marker of the heart muscle lesion) which confirmed the role of oxidative stress in the pathogenesis of cardiac damage. The tempol treatment significantly reduced the intensity of inflammation and oxidative damage and decreased the morphological evidence of pancreas injury at early AP stages. Moreover, it markedly attenuated AP-induced cardiac damage revealed by normalization of the –SH group levels and CK-MB activity. On the basis of these studies, it is possible to conclude that tempol has a profound protective effect against cardiac and pancreatic damage induced by AP.

Oxidative stress and inflammatory signaling in cerulein pancreatitis

Oxidative stress is considered to be an important regulator of the pathogenesis of acute pancreatitis. Reactive oxygen species (ROS) regulate the activation of inflammatory cascades, the recruitment of inflammatory cells and tissue damage in acute pancreatitis. A hallmark of the inflammatory response in pancreatitis is the induction of cytokine expression, which is regulated by a number of signaling molecules including oxidant-sensitive transcription factors such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), signal transducer and activator of transcription 3 (STAT3), and mitogen-activated protein kinases (MAPKs). Cross-talk between ROS and pro-inflammatory cytokines is mediated by NF-κB, AP-1, STAT3, and MAPKs; this crosstalk amplifies the inflammatory cascade in acute pancreatitis. Therapeutic studies have shown that antioxidants and natural compounds can have beneficial effects for patients with pancreatitis and can also influence the expression of proinflammatory cytokines in cerulein-induced pancreatitis. Since oxidative stress may activate inflammatory signaling pathways and contribute to the development of pancreatitis, antioxidant therapy may alleviate the symptoms or prevent the development of pancreatitis. Since chronic administration of high doses of antioxidants may have deleterious effects, dosage levels and duration of antioxidant treatment should be carefully determined.

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.

Admission levels of soluble CD137 are increased in patients with acute pancreatitis and are associated with subsequent complications

The progression of acute pancreatitis to necrotizing pancreatitis which often results in high morbidity and mortality is difficult to predict. Here we report that serum concentrations of sCD137 are increased in patients with acute pancreatitis. Admission levels and 10-day median sCD137 levels positively correlate with markers of biliary pancreatitis and the 10-day sCD137 median is significantly higher in metabolic than in alcoholic pancreatitis. Serum concentrations of sCD137 at time of admission and the 10-day median of sCD137 correlate with the Ranson and APACHE II disease scores but not with the radiological Balthazar and Schroeder scores that reflect pancreatic and peripancreatic necrosis. Further, sCD137 levels correlate with the probability of complications and lethality. The association of sCD137, a product of activated T cells, with the severity of acute pancreatitis suggests that T cells contribute to the pathogenesis of acute pancreatitis.

Reactive oxygen species induced by bile acid induce apoptosis and protect against necrosis in pancreatic acinar cells

BACKGROUND & AIMS

Oxidative stress is implicated in the pathogenesis of pancreatitis, but clinical trials of antioxidants have produced conflicting results. We examined the role of intracellular reactive oxygen species (ROS) in pancreatic acinar cell injury.

METHODS

Freshly isolated murine and human pancreatic acinar cells were studied using confocal microscopy to measure changes in intracellular and mitochondrial ROS concentrations ([ROS]I and [ROS]M), cytosolic and mitochondrial calcium concentrations ([Ca2+]C and [Ca2+]M), reduced nicotinamide adenine dinucleotide phosphate levels, and death pathways in response to taurolithocholate acid sulfate (TLC-S) or the oxidant menadione. Ca2+-activated Cl- currents were measured using whole-cell patch clamp, with or without adenosine triphosphate (ATP).

RESULTS

TLC-S induced prolonged increases in [Ca2+]C and [Ca2+]M, which led to dose-dependent increases in [ROS]I and [ROS]M, impaired production of ATP, apoptosis, and necrosis. Inhibition of the antioxidant reduced nicotinamide adenine dinucleotide phosphate quinine oxidoreductase by 2,4-dimethoxy-2-methylnaphthalene potentiated the increases in [ROS]I and apoptosis but reduced necrosis, whereas the antioxidant N-acetyl-L-cysteine reduced [ROS]I and apoptosis but increased necrosis. Inhibition of mitochondrial ROS production prevented apoptosis but did not alter necrosis; autophagy had no detectable role. Patched ATP prevented sustained increases in [Ca2+]C and necrosis.

CONCLUSIONS

Increases in [ROS]M and [ROS]I during bile acid injury of pancreatic acinar cells promote apoptosis but not necrosis. These results indicate that alternative strategies to antioxidants are required for oxidative stress in acute pancreatitis.

Probiotics enhance pancreatic glutathione biosynthesis and reduce oxidative stress in experimental acute pancreatitis

Factors determining severity of acute pancreatitis (AP) are poorly understood. Oxidative stress causes acinar cell injury and contributes to the severity, whereas prophylactic probiotics ameliorate experimental pancreatitis. Our objective was to study how probiotics affect oxidative stress, inflammation, and acinar cell injury during the early phase of AP. Fifty-three male Sprague-Dawley rats were randomly allocated into groups: 1) control, 2) sham procedure, 3) AP with no treatment, 4) AP with probiotics, and 5) AP with placebo. AP was induced under general anesthesia by intraductal glycodeoxycholate infusion (15 mM) and intravenous cerulein (5 microg.kg(-1).h(-1), for 6 h). Daily probiotics or placebo were administered intragastrically, starting 5 days prior to AP. After cerulein infusion, pancreas samples were collected for analysis including lipid peroxidation, glutathione, glutamate-cysteine-ligase activity, histological grading of pancreatic injury, and NF-kappaB activation. The severity of pancreatic injury correlated to oxidative damage (r = 0.9) and was ameliorated by probiotics (1.5 vs. placebo 5.5; P = 0.014). AP-induced NF-kappaB activation was reduced by probiotics (0.20 vs. placebo 0.53 OD(450nm)/mg nuclear protein; P < 0.001). Probiotics attenuated AP-induced lipid peroxidation (0.25 vs. placebo 0.51 pmol malondialdehyde/mg protein; P < 0.001). Not only was AP-induced glutathione depletion prevented (8.81 vs. placebo 4.1 micromol/mg protein, P < 0.001), probiotic pretreatment even increased glutathione compared with sham rats (8.81 vs. sham 6.18 miccromol/mg protein, P < 0.001). Biosynthesis of glutathione (glutamate-cysteine-ligase activity) was enhanced in probiotic-pretreated animals. Probiotics enhanced the biosynthesis of glutathione, which may have reduced activation of inflammation and acinar cell injury and ameliorated experimental AP, via a reduction in oxidative stress.

Severe acute pancreatitis: Pathogenetic aspects and prognostic factors

Approximately 20% of patients with acute pancreatitis develop a severe disease associated with complications and high risk of mortality. The purpose of this study is to review pathogenesis and prognostic factors of severe acute pancreatitis (SAP). An extensive medline search was undertaken with focusing on pathogenesis, complications and prognostic evaluation of SAP. Cytokines and other inflammatory markers play a major role in the pathogenesis and course of SAP and can be used as prognostic markers in its early phase. Other markers such as simple prognostic scores have been found to be as effective as multifactorial scoring systems (MFSS) at 48 h with the advantage of simplicity, efficacy, low cost, accuracy and early prediction of SAP. Recently, several laboratory markers including hematocrit, blood urea nitrogen (BUN), creatinine, matrix metalloproteinase-9 (MMP-9) and serum amyloid A (SAA) have been used as early predictors of severity within the first 24 h. The last few years have witnessed a tremendous progress in understanding the pathogenesis and predicting the outcome of SAP. In this review we classified the prognostic markers into predictors of severity, pancreatic necrosis (PN), infected PN (IPN) and mortality.

Hyperbaric oxygen therapy for severe acute pancreatitis

Despite improvements in the supportive management of severe acute pancreatitis over the last decade, the morbidity and mortality rate remains high. The main feature of this condition is pancreatic necrosis leading to sepsis, with both localized and systemic inflammatory response syndromes. Early pathophysiological changes of the pancreas include alterations in microcirculation, ischemia reperfusion injury, and leukocyte and cytokine activation. The efficacy of hyperbaric oxygen (HBO) therapy in improving these pathophysiological disturbances is documented for various conditions. However, its effect in the treatment of severe acute pancreatitis is undetermined. This report documents the case of a 56-year-old woman presenting with severe acute pancreatitis treated by HBO therapy. The severity of disease was based on an Acute Physiology and Chronic Health Evaluation (APACHE II) illness grading score of 11 and a Baltazar based computed tomography severity index (CTSI) score of 9. Administration of 100% oxygen was commenced within 72 h of presentation at a pressure of 2.5 atmospheres for 90 min and given twice daily for a total of 5 days. Therapy was well tolerated with improvements in APACHE II and CTSI grading scores. HBO therapy for severe acute pancreatitis appeared to be safe and may have a role in improving treatment outcomes. Further study is required.

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.

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.

Oxidative stress in blood of patients with alcohol-related pancreatitis

To determine the possible role of oxidative stress in alcoholic pancreatitis, the authors measured the ability of blood neutrophils of 22 patients with acute and 20 patients with chronic alcoholic pancreatitis to produce superoxide anion (O2-) and hydrogen peroxide (H2O2), spontaneously and after in vitro stimulation with phorbol ester and compared it with that of neutrophils isolated from the blood of 16 healthy controls. In addition, they measured serum activities of superoxide dismutase, catalase, and the serum concentration of glutathione peroxidase (GPx). Phorbol ester-induced O2- and H2O2 production in neutrophils of patients with acute and chronic pancreatitis was greater than in controls, but these differences, except of superoxide anion production by neutrophils of patients with chronic pancreatitis, were not statistically significant because of large individual differences. Spontaneous resting production of O2- and H2O2 by neutrophils of patients with chronic pancreatitis was significantly greater than in the controls. Superoxide dismutase and catalase activity was greater in sera of both groups of patients with acute and chronic alcoholic pancreatitis than in controls, but GPx concentration was significantly less in the sera of patients with chronic pancreatitis. Impaired GPx production and increased production of O2- and H2O2 by neutrophils may result in increased lipid peroxidation and could play a role in the pathogenesis of chronic alcoholic pancreatitis.

Differential upregulation of cellular adhesion molecules at the sites of oxidative stress in experimental acute pancreatitis

BACKGROUND

Severe acute pancreatitis (AP)(2) is associated with exaggerated leukocyte adherence and activation. Endothelial cellular adhesion molecules (CAMs) can be induced by cytokines, but also directly by oxygen free radicals (OFRs), mediated by nuclear factor kappa-B (NF-kappa B). We investigated the behavior of inducible CAMs in relation to pancreatic oxidative stress. Our novel modification of cerium capture histochemistry (reaction of OFRs with cerium produces laser reflective Ce perhydroxide precipitates) combined with reflectance confocal laser scanning microscopy (CLSM) allows the histological codemonstration of in vivo OFR production and immunolabeled CAMs, or NF-kappa B.

METHODS

Taurocholate AP was induced in rats; sham operated and normal animals served as controls. To achieve in situ, in vivo reaction of cerium with OFRs, animals were perfused with CeCl(3) solution at different time points (1, 2, 8, 24 h) and then sacrificed. E-selectin, P-selectin, ICAM-1, VCAM, and NF-kappa B p65 were labeled by immunofluorescence (IF) on frozen sections of cerium perfused pancreata. IF and Ce perhydroxide reflectance were simultaneously detected by CLSM. Pancreatic gene expression of the same CAMs was quantified by competitive RT-PCR (MIMIC internal control).

RESULTS

Control pancreata showed negligible reflectance and minimal CAM expression. Early (1, 2 h) AP samples were characterized by intense, heterogeneous acinar OFR production, strong P-selectin, and increasing ICAM expression, with nuclear translocation of p65, histologically all colocalizing with the areas of acinar oxidative stress. Adherent polymorphonuclear leukocytes (PMNs) displayed weak OFR formation. Later (8, 24 h), a slowly declining P-selectin, but persisting ICAM-1 expression, was paralleled by widespread adherence of PMNs producing surprisingly large amounts of OFRs. VCAM and E-selectin showed a mild increase at 24 h. CAM gene activation was in good correlation with the protein expression.

CONCLUSIONS

The early acinar oxidative stress is colocalized with NF-kappa B activation, preferential P-selectin, and ICAM upregulation in this AP model. Subsequently, adherent, activated PMNs become the major source of OFRs, thereby contributing to tissue damage.

Alcohol intake, cigarette smoking, and body mass index in patients with alcohol-associated pancreatitis

The differential diagnosis between acute and chronic alcohol-associated pancreatitis is often difficult or impossible at onset of the disease. A study was conducted to determine possible relationships between patients suffering from a first episode of acute alcoholic pancreatitis and patients with unequivocal chronic alcoholic pancreatitis, comparing age, drinking and smoking habits, and body mass index (BMI). Two groups of men were considered. The first group consisted of 67 patients with a diagnosis of acute alcohol-associated pancreatitis in the absence of other potential pathogenic factors; in this group, 48 of the 56 patients surviving the acute attack were submitted to imaging studies for a median period of 9 years. The second group consisted of 396 patients with chronic alcoholic pancreatitis with a median follow-up period of 12 years. The variables that differed significantly in the two groups were BMI (p < 0.009) and number of smokers (p < 0.001). Logistic regression analysis selected only BMI with an odds ratio of 1.19 (95% CI, 1.07-1.33; p < 0.00015) in favor of acute alcoholic pancreatitis. In male patients, from an epidemiologic standpoint, only smoking habits and BMI are significant differences at clinical onset between the two types of pancreatitis.

Suppression of NF-kappaB activation and cytokine production by N-acetylcysteine in pancreatic acinar cells

Reactive oxygen species (ROS), generated by infiltrating neutrophils, are considered as an important regulator in the pathogenesis and development of pancreatitis. A hallmark of the inflammatory response is the induction of cytokine gene expression, which may be regulated by oxidant-sensitive transcription factor, nuclear factor-kappaB (NF-kappaB). Present study aims to investigate whether neutrophils primed by 4beta-phorbol 12beta-myristate 13alpha-acetate (PMA) affect the productions of H(2)O(2) and lipid peroxide (LPO), NF-kappaB activation and cytokine production in pancreatic acinar cells, and whether these alterations were inhibited by N-acetylcysteine (NAC) and superoxide dismutase (SOD). Neutrophils generated ROS by stimulation with PMA, which was inhibited by NAC and SOD. In acinar cells, PMA-primed neutrophils increased the productions of H(2)O(2), LPO, and cytokines both time and dose dependently. PMA-primed neutrophils resulted in the activation of two species of NF-kappaB dimers (a p50/p65 heterodimer and a p50 homodimer) in acinar cells. Both NAC and SOD inhibited neutrophil-induced, oxidant-mediated alterations in acinar cells. In conclusion, ROS, generated by neutrophils, activates NF-kappaB, resulting in upregulation of inflammatory cytokines in acinar cells. Antioxidants such as NAC might be useful antiinflammatory agents by inhibiting oxidant-mediated activation of NF-kappaB and decreasing cytokine production.

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

Using a retrograde infusion sodium taurocholate pancreatitis model in the rat treatment with oxygen radical scavengers or monoclonal anti-ICAM-1 antibody decreased tissue damage and polymorphonuclear leukocytes (PMN) infiltration. Scavengers or anti-ICAM-1 treatment attenuated the activating capacity of blood PMNs following zymosan stimulation. The local production of oxygen free radicals in the pancreas by systemic infusion of hypoxanthine and regional infusion of xanthine oxidase did not induce acute pancreatitis, although an increase of infiltrating PMNs was observed. Our data suggest that oxygen free radicals and infiltrating PMNs aggravate acute pancreatitis and that both are important mediators of local destruction and systemic activation of PMNs.

Cerium-based histochemical demonstration of oxidative stress in taurocholate-induced acute pancreatitis in rats. A confocal laser scanning microscopic study

Direct in vivo histological detection of oxygen-derived free radicals (OFRs) in inflammatory conditions is not fully resolved. We report an application of cerium histochemistry (in which capture of OFRs by Ce atoms results in laser-reflectant cerium-perhydroxide precipitates) combined with reflectance confocal laser scanning microscopy (CLSM) to demonstrate the evolution of oxidative stress in taurocholate-induced acute pancreatitis (AP) in rats. Animals were perfused with CeCl(3) in vivo and cryostat sections of pancreata were studied by CLSM. Vascular endothelium was immunolabeled for PECAM-1. OFR production by isolated polymorphonuclear leukocytes (PMNs) incubated in vitro with CeCl(3) was quantified by image analysis. In the pancreas, strong OFR-derived cerium reflectance signals were seen in acinar cells at 1-2 hr, capillaries and small venules were frequently engorged by cerium precipitates, and adherent PMNs presented weak intracellular reflectance signals. At 8-24 hr, acinar cell OFR production decreased, whereas adherent/transmigrated PMNs displayed abundant intra- and pericellular reflectance. PECAM-1 expression was unchanged. PMNs from ascites or blood showed significant (p<0.01) time-dependent OFR production, plateauing from 2 hr. The modified cerium capture/CLSM method allows the co-demonstration of in vivo oxidative stress and cellular structures labeled with fluorescent markers. In vivo oxidative stress was shown histologically for the first time in experimental AP.

Chronic ethanol administration causes oxidative stress in the rat pancreas

There is increasing evidence implicating oxidative stress in the pathogenesis of both acute and chronic pancreatitis. Because ethanol is a major cause of pancreatitis in Western society, the aim of this study was to determine whether chronic ethanol administration results in oxidative stress in the pancreas. Twelve pairs of rats were fed a diet containing ethanol as 36% of calories or an isocaloric control diet for 4 weeks. Ethanol feeding resulted in a 46% increase in pancreatic malondialdehyde (p=0.006). In addition, total pancreatic glutathione was increased by 22% (p=0.005). These biochemical changes occurred in the absence of histologic evidence of inflammation or necrosis, implying that the observed oxidative stress is a primary phenomenon rather than part of an inflammatory response.