Role of oxidative stress in the pathogenesis of acute pancreatitis

Pyroptosis in acute pancreatitis and its therapeutic regulation

Pyroptosis defines a new type of GSDMs-mediated programmed cell death, distinguishes from the classical concepts of apoptosis and necrosis-mediated cell death and is prescribed by cell swelling and membrane denaturation, leading to the extensive secretion of cellular components and low-grade inflammatory response. However, NLRP3 inflammasome activation can trigger its downstream inflammatory cytokines, leading to the activation of pyroptosis-regulated cell death. Current studies reveal that activation of caspase-4/5/11-driven non-canonical inflammasome signaling pathways facilitates the pathogenesis and progression of acute pancreatitis (AP). In addition, a large number of studies have reported that NLRP3 inflammasome-dependent pyroptosis is a crucial player in driving the course of the pathogenesis of AP. Excessive uncontrolled GSDMD-mediated pyroptosis has been implicated in AP. Therefore, the pyroptosis-related molecule GSDMD may be an independent prognostic biomarker for AP. The present review paper summarizes the molecular mechanisms of pyroptotic signaling pathways and their pathophysiological impacts on the progress of AP. Moreover, we briefly present some experimental compounds targeting pyroptosis-regulated cell death for exploring novel therapeutic directions for the treatment and management of AP. Our review investigations strongly suggest that targeting pyroptosis could be an ideal therapeutic approach in AP.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Viral-Attributed Acute Pancreatitis: A Systematic Review

Infectious etiologies are rare cause of acute pancreatitis (AP). We sought to investigate the frequency of viral-attributed AP (VIAP) and describe its natural course and clinical features. Comprehensive review of PubMed and EMBASE in English until December 31, 2019, was performed. AP diagnosis and severity were defined per the Revised Atlanta Classification. Viral infections were diagnosed by serology and/or histology. A diagnosis of viral infection, with a concurrent AP diagnosis, a temporal resolution of both entities, and the attempt to exclude the most common etiologies of AP defined VIAP. Two independent reviewers reviewed eligible publications. Bias risk was assessed with the Murad tool. A total of 209 cases identified in 128 publications met inclusion criteria. Mean age was 38.9 ± 1.28 years. Male-to-female ratio was 2.2:1, and 28% of patients were immunocompromised. Viral hepatitis (A, B, C, D and E) was the most common virus and accounted for 34.4% of cases, followed by coxsackie and echoviruses (14.8%), hemorrhagic fever viruses (12.4%), CMV (12.0%), VZV (10.5%), mumps and measles (3.8%), primary HIV infection (3.8%), HSV (1.9%), EBV (1.9%), and the remainder of cases (2.9%) attributed to adenovirus, influenza H1N1, and multiple viruses. Severity of AP was: 43.1% mild, 11.7% moderately severe, 32.4% severe. Death occurred in 42 (20.1%) patients. A significant portion of VIAP patients were immunocompromised (28.0%) and accounted for 71.4% of mortality cases. Mortality was higher than that reported for AP from other etiologies in the literature.

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

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

Infectious causes of acute pancreatitis: A systematic review

BACKGROUND

Infectious etiologies of acute pancreatitis (AP) are rare and include viruses, bacteria, mycobacteria, parasites, and fungi. We aimed to conduct a comprehensive review on infectious etiologies of AP analyzing the frequency, clinical features, and outcomes of individuals presenting with this condition.

METHODS

Eligible articles reporting on AP attributed to infectious etiologies were included. A comprehensive literature search of PubMed from time of inception and until September 6,2019 was performed using all relevant MeSH (medical subject heading) keywords. Articles were assessed for eligibility and independently reviewed by two reviewers for clinical features of AP, local complications, and mortality. Methodological quality of included studies was evaluated using the Murad tool.

RESULTS

A total of 212 articles were included, of which 168 (79.2%) were at high risk of bias. 320 cases of AP were identified. Viruses were the leading etiology of infection attributed AP (65.3%) followed by helminths (19.1%), and bacteria (12.5%). Protozoa, mycobacteria, and fungi accounted for the remaining 3.1% of cases. Mean age was 40.5 ± 18.4 years and M:F ratio was 1.94:1. Mortality occurred in 50 patients. Mortality rate was higher in the virus attributed AP patients than AP from other infectious etiologies (21.8% vs. 7.0%, p < 0.0005).

INTERPRETATION

Literature quality on infection attributed AP is limited. Virus attributed AP appears to carry a higher mortality than other etiologies of infection attributed AP.

Impairment of PGC-1 Alpha Up-Regulation Enhances Nitrosative Stress in the Liver during Acute Pancreatitis in Obese Mice

Acute pancreatitis is an inflammatory process of the pancreatic tissue that often leads to distant organ dysfunction. Although liver injury is uncommon in acute pancreatitis, obesity is a risk factor for the development of hepatic complications. The aim of this work was to evaluate the role of PGC-1α in inflammatory response regulation in the liver and its contribution to the detrimental effect of obesity on the liver during acute pancreatitis. For this purpose, we induced acute pancreatitis by cerulein in not only wild-type (WT) and PGC-1α knockout (KO) mice, but also in lean and obese mice. PGC-1α levels were up-regulated in the mice livers with pancreatitis. The increased PGC-1α levels were bound to p65 to restrain its transcriptional activity toward Nos2. Lack of PGC-1α favored the assembly of the p65/phospho-STAT3 complex, which promoted Nos2 expression during acute pancreatitis. The increased transcript Nos2 levels and the pro-oxidant liver status caused by the down-regulated expression of the PGC-1α-dependent antioxidant genes enhanced nitrosative stress and decreased energy charge in the livers of the PGC-1α KO mice with pancreatitis. It is noteworthy that the PGC-1α levels lowered in the obese mice livers, which increased the Nos2 mRNA expression and protein nitration levels and decreased energy charge during pancreatitis. In conclusion, obesity impairs PGC-1α up-regulation in the liver to cause nitrosative stress during acute pancreatitis.

8α-Hydroxypinoresinol isolated from Nardostachys jatamansi ameliorates cerulein-induced acute pancreatitis through inhibition of NF-κB activation

Acute pancreatitis (AP) is a severe inflammatory condition of the pancreas, with no specific treatment available. We have previously reported that Nardostachys jatamansi (NJ) ameliorates cerulein-induced AP. However, the specific compound responsible for this inhibitory effect has not been identified. Therefore, in the present study, we focused on a single compound, 8α-hydroxypinoresinol (HP), from NJ. The aim of this study was to determine the effect of HP on the development of pancreatitis in mice and to explore the underlying mechanism(s). AP was induced by the injection of cerulein (50 μg/kg/h) for 6 h. HP (0.5, 5 or 10 mg/kg, i.p.) was administered 1 h prior to and 1, 3 or 5 h after the first cerulein injection, with vehicle- and DMSO-treated groups as controls. Blood samples were collected to determine serum levels of amylase, lipase, and cytokines. The pancreas was removed for morphological examination, myeloperoxidase (MPO) assays, cytokine assays, and assessment of nuclear factor (NF)-κB activation. The lungs were removed for morphological examination and MPO assays. Administration of HP dramatically improved pancreatic damage and pancreatitis-associated lung damage and also reduced amylase and lipase activities in serum. Moreover, administration of HP reduced the production of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in the pancreas and serum during AP. In addition, the administration of HP inhibited degradation of inhibitory κ-Bα (Iκ-Bα), NF-κB p65 translocation into nucleus and NF-κB binding activity in the pancreas. Our results suggest that HP exerted therapeutic effects on pancreatitis and these beneficial effects may be due to the inhibition of NF-κB activation.

Histone deacetylase inhibitor MGCD0103 protects the pancreas from streptozotocin-induced oxidative stress and β-cell death

Inhibition of histone deacetylase (HDAC) suppresses inflammation of pancreatic islets and apoptosis of β-cells. However, the underlying molecular mechanism is unclear. In the present study, we demonstrate that MGCD0103 (MGCD), an HDAC inhibitor, protects the pancreas from streptozotocin (STZ)-induced oxidative stress and cell death. Sprague-Dawley rats were intraperitoneally injected with STZ (40 mg/kg) to induce type I diabetes. MGCD (10 μg/day) was infused with osmotic mini-pump for 4 weeks. Pancreatic insulin and macrophage infiltration were analyzed by immunohistochemistry. Cellular level of reactive oxygen species (ROS) was evaluated with fluorescence-activated cell sorting. Tetramethylrhodamine ethyl ester was used to analyze mitochondrial membrane potential. Activation of caspase-3 was analyzed by western blotting. Chromatin immunoprecipitation was performed to investigate the binding affinity of specificity protein 1 (SP1) on the promoters of target genes. mRNA expression was analyzed by quantitative real-time polymerase chain reaction. As a result, we found that MGCD infusion ameliorated STZ-induced hyperglycemia, islet deformation, decreased insulin level, and macrophage infiltration. STZ injection promoted the production of ROS, which induced caspase activity and β-cell death. 4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL), a mimetic of superoxide dismutase (SOD), reduced STZ-induced caspase activity and β-cell death. MGCD treatment increased SOD expression and histone acetylation level on promoters. Infusion of MGCD promoted acetylation of SP1 and its enrichment on SOD promoters. Thus, MGCD protects pancreatic β-cells from STZ-induced oxidative stress and cell death through the induction of antioxidant enzymes such as SODs.

SRT1720 ameliorates sodium taurocholate-induced severe acute pancreatitis in rats by suppressing NF-κB signalling

Severe acute pancreatitis (SAP) is a medical emergency that is often associated with multiple organ failure and high mortality. Although an SAP diagnosis requires prompt treatment, therapeutic options remain limited. SRT1720 is a newly formulatedSIRT1 activator that exerts multiple pharmacological activities with beneficial health effects. However, its potential as an SAP treatment has not been explored. The current study assessed the effect of SRT1720 on a rat model of sodium taurocholate-induced SAP and explored the underlying mechanism. SAP was induced in rats by retrograde injection of a 3.5% sodium taurocholate solution (1 ml/kg) in the biliopancreatic duct. SRT1720 (5 mg/kg) was administered intraperitoneally after sodium taurocholate exposure. Serum samples were analysed for inflammatory cytokine levels and select enzymatic activities using the enzyme-linked immunosorbent assay and commercial enzyme activity assay kits, respectively; protein expression levels were evaluated by western blotting; mRNA levels of biomarkers were determined by quantitative real-time PCR; histopathological changes were analysed by haematoxylin and eosin staining and immunohistochemistry.SRT1720 treatment significantly reduced serum amylase, lipase, pancreatic histological scores, proinflammatory cytokine (TNF-α and IL-6) levels, and expression of NF-κB and p65 in sodium taurocholate-induced SAP rats. Importantly, the treatment stimulated SIRT1 and IκBα levels in pancreatic tissue. Our data suggest that SRT1720 protects rats from sodium taurocholate-induced SAP by suppressing the NF-κB signalling pathway.

Single Nucleotide Polymorphisms in the Vitamin D Receptor Gene (VDR) May Have an Impact on Acute Pancreatitis (AP) Development: A Prospective Study in Populations of AP Patients and Alcohol-Abuse Controls

Vitamin D imbalance is suggested to be associated with the development of pancreatitis. Single nucleotide polymorphisms (SNPs), Apa-1, Bsm-1, Fok-1, and Taq-1, in the vitamin D receptor gene (VDR) are known in various diseases, but not yet in pancreatitis. The aim of this study was to explore possible associations of the four SNPs in the VDR receptor gene in a population of acute pancreatitis patients and alcohol-abuse controls, and to investigate the association with acute pancreatitis (AP) susceptibility. The study population (n = 239) included acute pancreatitis patients (n = 129) and an alcohol-abuse control group (n = 110). All patients met the Diagnostic and Statistical Manual of Mental Disorders (DSM IV) criteria for alcohol dependence. DNA was extracted from peripheral leukocytes and analyzed for VDR polymorphisms using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Odd ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression analysis. To date, we have found allele T in Taq-1 (OR = 2.61; 95% CI: 1.68⁻4.03; p < 0.0001) to be almost three times more frequent in the AP group compared to the alcohol-abuse control patients. Polymorphism Taq-1 occurring in the vitamin D receptor may have an impact on the development of acute pancreatitis due to the lack of the protective role of vitamin D.

Fentanyl Ameliorates Severe Acute Pancreatitis-Induced Myocardial Injury in Rats by Regulating NF-κB Signaling Pathway

Background

Acute pancreatitis (AP) is a sudden inflammation of the pancreas. It results in multiple, severe complications, and 15–20% of patients develop severe acute pancreatitis (SAP) with mortality as high as 30%. Consequently, it is imperative to develop an effective therapy for SAP.

Material/Methods

We used 30 adult male Sprague Dawley (SD) rats. Rats were randomly divided into 3 groups – sham, SAP, and fentanyl+SAP – with 10 rats in each group. An automatic biochemical analyzer was used to analyze the concentration of creatine kinase isoenzyme (CK-MB) and lactate dehydrogenase (LDH). Terminal-deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL) assay was applied to assess the cell apoptosis rate. Pathological changes in pancreas/heart were detected with hematoxylin and eosin (HE) staining. Western immunoblot assay was used to analyze protein levels of interleukin (IL)-1β, IL-6, and IκB.

Results

Fentanyl pre-treatment inhibits SAP-induced elevation of CK-MB/LDH concentrations in serum. Compared with the sham group, SAP generates a higher brown/yellow staining rate, which is abated by fentanyl. In the pancreas, SAP generated more serious interstitial edema/hemorrhage and fat necrosis than in the sham group, which are attenuated by fentanyl. Likewise, compared to the sham group, SAP generates swelled/disordered myocardial fibers and congested blood vessels in myocardium, which are ameliorated by fentanyl. In the sham group, there was little IL-1β/IL-6, and fentanyl significantly inhibited SAP-induced up-regulation of IL-1β/IL-6 levels. Compared with the sham group, SAP significantly reduced IκB level, which was rescued by fentanyl.

Conclusions

Fentanyl effectively alleviates SAP-induced pancreas and heart injuries through regulating the nuclear factor-κB (NF-κB) signaling pathway.

Pathophysiological mechanisms in acute pancreatitis: Current understanding

The precise mechanisms involved in the pathophysiology of acute pancreatitis (AP) are still far from clear. Several earlier studies have focused mainly on pancreatic enzyme activation as the key intracellular perturbation in the pancreatic acinar cells. For decades, the trypsin-centered hypothesis has remained the focus of the intra-acinar events in acute pancreatitis. Recent advances in basic science research have lead to the better understanding of various other mechanisms such as oxidative and endoplasmic stress, impaired autophagy, mitochondrial dysfunction, etc. in causing acinar cell injury. Despite all efforts, the clinical outcome of patients with AP has not changed significantly over the years. This suggests that the knowledge of the critical molecular pathways in the pathophysiology of AP is still limited. The mechanisms through which the acinar cell injury leads to local and systemic inflammation are not well understood. The role of inflammatory markers and immune system activation is an area of much relevance from the point of view of finding a target for therapeutic intervention. Some data are available from experimental animal models but not much is known in human pancreatitis. This review intends to highlight the current understanding in this area.

Virus-inhibiting activity of dihydroquercetin, a flavonoid from Larix sibirica, against coxsackievirus B4 in a model of viral pancreatitis

Members of the family Picornaviridae, in particular, enteroviruses, represent a serious threat to human health. They are responsible for numerous pathologies ranging from mild disease to fatal outcome. Due to the limited number of safe and effective antivirals against enteroviruses, there is a need for search and development of novel drugs with various mechanisms of activity against enteroviruses-induced pathologies. We studied the effect of dihydroquercetin (DHQ), a flavonoid from larch wood, on the course of pancreatitis of white mice caused by coxsackievirus B4 (CVB4). DHQ was applied intraperitoneally at doses of 75 or 150 mg/kg/day once a day for 5 days postinfection (p.i.) starting on day 1 p.i., and its effect was compared to that of the reference compound ribavirin. The application of DHQ resulted in a dose-dependent decrease in the virus titer in pancreatic tissue, reaching, at the highest dose, 2.4 logs on day 5 p.i. Also, the application of DHQ led to restoration of antioxidant activity of pancreatic tissue that was impaired in the course of pancreatitis. Morphologically, pancreatic tissue of DHQ-treated animals demonstrated less infiltration with inflammatory cells and no signs of tissue destruction compared to placebo-treated mice. Both ribavirin- and DHQ-treated animals developed fewer foci of pancreatic inflammation per mouse, and these foci contained fewer infiltrating cells than those in placebo-treated mice. The effect of DHQ was comparable to or exceeded that of ribavirin. Taken together, our results suggest high antiviral activity of DHQ and its promising potential in complex treatment of viral pancreatitis.

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

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

Acute Pancreatitis and Splenic Vein Thrombosis due to Hypertriglyceridemia

Acute pancreatitis (AP) is a condition characterised by the activation of the normally inactive digestive enzymes due to an etiological factor and digestion of the pancreatic tissues, resulting in extensive inflammation and leading to local, regional, and systemic complications in the organism. It may vary from the mild edematous to the hemorrhagic and severely necrotising form. The most common causes are biliary stones and alcohol abuse. In this case study, we would like to present a patient with AP due to hypertriglyceridemia (HPTG), which is a rare cause of pancreatitis, and splenic vein thrombosis, which is a rare complication of pancreatitis.

Trimetazidine significantly reduces cerulein-induced pancreatic apoptosis

OBJECTIVE

Acute pancreatitis continues to be associated with significant rates of mortality and morbidity, and therapeutic options are still very limited. We aimed to investigate the efficacy of trimetazidine on cerulein-induced pancreatic apoptosis and histopathological and biochemistrical consequences of acute pancreatitis.

METHODS

Thirty-two Wistar albino rats were randomized into four groups (group 1: control group; group 2: acute pancreatitis group; group 3: acute pancreatitis and trimetazidine treatment group; group 4: placebo group). Acute edematous pancreatitis was induced by subcutaneous cerulein injection (20 μg/kg) four times at one-hour intervals. Trimetazidine was prepared in suspension form. In group 3, after gas anesthesia, trimetazidine was administrated to rats via a catheter. Serum interleukin (IL)-1β, tumor necrosis factor (TNF)-α, amylase, lipase and leukocyte levels, pancreatic apoptotic status and pancreatic Schoenberg scores were determined for all groups. Results are given as the mean ± SD. A value of P<0.05 was accepted as statistically significant. SPSS for Windows v15.0 was used for statistical analyses.

RESULTS

In the acute pancreatitis group IL-1β, amylase, lipase and leukocyte levels were elevated and pancreatic histopathological evaluation revealed a diagnosis of acute pancreatitis IL-1β amylase and lipase levels and pancreatic inflammation were decreased significantly in the trimetazidine group (P<0.01). White blood cell counts and TNF-α concentrations for the trimetazidine group and the acute pancreatitis group were not significantly different. Trimetazidine significantly reduced apoptosis in pancreatic tissues and Schoenberg scores were also significantly reduced (P<0.05).

CONCLUSION

In this study, we showed that trimetazidine treatment significantly decreases the levels of IL-1β, amylase and lipase reduces pancreatic apoptosis and ameliorates the histopathological findings of cerulein-induced acute pancreatitis. Trimetazidine could be a new therapeutic option in the early treatment of acute pancreatitis.

Redox signaling in acute pancreatitis

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

Astragaloside IV ameliorates acute pancreatitis in rats by inhibiting the activation of nuclear factor-κB

This study aimed to investigate the effects of astragaloside IV (AS-IV; 3-O-β-D-xylopyranosyl-6-O-β-D-glucopyranosylcycloastragenol), which has been reported to have comprehensive pharmacological functions, on sodium taurocholate (NaTc)/L-arginine (L-Arg)-induced acute pancreatitis (AP) in rats in vivo and in rat pancreatic acinar cells in vitro. NaTc-induced experimental AP was induced in rats by injecting 4% NaTc (0.1 ml/100 g) in the retrograde direction of the biliopancreatic duct. L-Arg-induced experimental AP was induced in rats by 2 intraperitoneal injections of 20% L-arg (3 g/kg), with an interval of 1 h between the injections. The rats were pre-treated AS-IV (50 mg/kg) or the vehicle (DMSO) 2 h prior to the induction of AP. Enzyme-linked immunosorbent assay, H&E staining, myeloperoxidase (MPO) activity, reverse transcription-quantitative PCR, western blot analysis and immunohistochemistry were used to evaluate the effects of AS-IV on AP. The results revealed that treatment with AS-IV significantly reduced serum amylase and lipase levels, pancreatic pathological alterations, the secretion of pro-inflammatory cytokines, MPO activity, and the protein expression of nuclear factor-κB (NF-κB) in vivo. Moreover, pre-treatment with AS-IV significantly increased the expression levels of manganese superoxide dismutase and cuprum/zinc superoxide dismutase. In the in vitro experiment, treatment of the cells with AS-IV aslo reduced rat pancreatic acinar cell necrosis and nuclear NF-κB activity, and enhanced the protein expression of superoxide dismutase. In conclusion, this study indicates that the protective effects of AS-IV on experimental AP in rats may be closely related to the inhibition of NF-κB. In addition, our results indicate that AS-IV may exert potential antioxidant effects on AP. Therefore, AS-IV may be an effective therapeutic agent for AP.

Evidence for a role of mitogen-activated protein kinases in the treatment of experimental acute pancreatitis

Acute pancreatitis (AP) is an inflammatory disease characterized by acute inflammation and necrosis of the pancreatic parenchyma. AP is often associated with organ failure, sepsis, and high mortality. The pathogenesis of AP is still not well understood. In recent years several papers have highlighted the cellular and molecular events of acute pancreatitis. Pancreatitis is initiated by activation of digestive enzymes within the acinar cells that are involved in autodigestion of the gland, followed by a massive infiltration of neutrophils and macrophages and release of inflammatory mediators, responsible for the local and systemic inflammatory response. The hallmark of AP is parenchymal cell necrosis that represents the cause of the high morbidity and mortality, so that new potential therapeutic approaches are indispensable for the treatment of patients at high risk of complications. However, not all factors that determine the onset and course of the disease have been explained. Aim of this article is to review the role of mitogen-activated protein kinases in pathogenesis of acute pancreatitis.

Effectiveness of interleukin-1 receptor antagonist (Anakinra) on cerulein-induced experimental acute pancreatitis in rats

AIM

Acute pancreatitis (AP) is defined as an inflammatory disease of the pancreas. The purpose of this study was to examine the effectiveness of Anakinra on cerulein-induced experimental pancreatitis rat model by using the results of biochemical and histopathological findings.

MATERIALS AND METHODS

Cerulein was administered to induce AP in rats. Group 1 was the sham group. Subcutancerulein was injected to the rats in group 2 for experimental pancreatitis group. In groups 3 and 4, 100 and 50 mg/kg intraperitoneal Anakinra were injected after the induction of experimental pancreatitis by subcutaneous cerulein in rats, respectively. Lastly, in group 5, rats were injected with intraperitoneal saline and subcutan cerulean for placebo group. The following parameters were evaluated: histopathological score of pancreatitis, apoptotic index, amylase, lipase, TNF-α levels, IL-1β and the leukocyte count.

RESULTS

When the results of serum amylase, lipase, TNF-α and IL-1β levels, the leukocyte count, histopathologic scores and apoptotic indices of control group compared to the results of other groups, the differences exhibited statistical significance (all p < 0.05). On the other hand, when the results of fourth group compared with the results of third group, the data demonstrated statistical insignificance (p > 0.05). However, no any significant differences were found between the results of fourth and fifth groups (p > 0.05).

CONCLUSION

In the light of these results, cerulein is an appropriate agent for experimental AP rat model and Anakinra has a favorable therapeutic effect on acute experimental pancreatitis model. Moreover, Anakinra significantly decreases cerulein-related pancreatic tissue injury and pancreatic apoptosis.

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

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

Redox signaling and histone acetylation in acute pancreatitis

Histone acetylation via CBP/p300 coordinates the expression of proinflammatory cytokines in the activation phase of inflammation, particularly through mitogen-activated protein kinases (MAPKs), nuclear factor-κB (NF-κB), and signal transducers and activators of transcription (STAT) pathways. In contrast, histone deacetylases (HDACs) and protein phosphatases are mainly involved in the attenuation phase of inflammation. The role of reactive oxygen species (ROS) in the inflammatory cascade is much more important than expected. Mitochondrial ROS act as signal-transducing molecules that trigger proinflammatory cytokine production via inflammasome-independent and inflammasome-dependent pathways. The major source of ROS in acute inflammation seems to be NADPH oxidases, whereas NF-κB, protein phosphatases, and HDACs are the major targets of ROS and redox signaling in this process. There is a cross-talk between oxidative stress and proinflammatory cytokines through serine/threonine protein phosphatases, tyrosine protein phosphatases, and MAPKs that greatly contributes to amplification of the uncontrolled inflammatory cascade and tissue injury in acute pancreatitis. Chromatin remodeling during induction of proinflammatory genes would depend primarily on phosphorylation of transcription factors and their binding to gene promoters together with recruitment of histone acetyltransferases. PP2A should be considered a key modulator of the inflammatory cascade in acute pancreatitis through the ERK/NF-κB pathway and histone acetylation.

Lung injury in acute pancreatitis: mechanisms underlying augmented secondary injury

Acute lung injury (ALI) and its more severe form, the acute respiratory distress syndrome (ARDS), are common complications of acute pancreatitis (AP). ALI/ARDS contribute to the majority of AP-associated deaths, particularly in the setting of secondary infection. Following secondary pulmonary infection there can be an exacerbation of AP-associated lung injury, greater than the sum of the individual injuries alone. The precise mechanisms underlying this synergism, however, are not known. In this review we discuss the main factors contributing to the development of augmented lung injury following secondary infection during AP and review the established models of AP in regard to the development of associated ALI.

Laparoscopic preconditioning protects against oxidative injury in cerulein-induced pancreatitis rats (an experimental study)

BACKGROUND

Laparoscopic cholecystectomy, particularly in the same hospital stay, has been widely recommended to treat gallstone-pancreatitis over the last decade. Although pancreatitis produces severe oxidative injury, laparoscopy exerts an additional effect over that is produced by pancreatitis. The preconditioning phenomenon previously reported as protective in open surgery is a beneficial maneuver also in laparoscopic surgery. So in the present study we have tried to find out the effect of laparoscopic preconditioning over the pancreatitis in cerulein-induced pancreatitis rats.

METHODS

Acute pancreatitis was induced in 24 rats weighing between 280 and 350 g by three subcutaneous injection of 80 μg/kg of body weight cerulein. A 1-cm midline laparotomy was performed for all rats, and then they were randomly assigned to one of the following three groups (n=8 for each): Group I (control), Group II (laparoscopy), and Group III (laparoscopic preconditioning [L-Pre]). After that, a catheter was placed into the peritoneum for the creation of the pneumoperitoneum (Pp) in all the animals except the control group. The rats of Groups II and III were subjected to 60 minutes of Pp with 15 mm Hg intraabdominal pressure followed by 30 minutes of deflation. The L-Pre procedure was applied to Group III immediately before the laparoscopic procedure. Blood samples were taken for biochemical assays. Pancreas tissue samples were taken for light microscope analysis.

RESULTS

The light microscopy of the pancreas tissues revealed that cerulein injection caused edema and sparse inflammatory cell infiltration mimicking the edematous pancreatitis. However, the application of laparoscopy over the pancreatitis produced significant inflammatory cell infiltration, acinus vacuolization, and necrosis (in one case) in addition to edema. But, the laparoscopic preconditioning maneuver applied before the laparoscopy significantly decreased in particular acinary vacuolization and cell infiltration. Therefore the total sum of the histopathological score of the L-Pre group was significantly less than that of the laparoscopy group. The biochemical analysis of the groups revealed that laparoscopy caused significant elevation of malondialdehyde levels and decrease of reduced glutathione values. However, the addition of preceding preconditioning produced significant amelioration of these parameters.

CONCLUSION

Laparoscopic preconditioning may be a useful method to decrease the oxidative injury in cases undergoing cholecystectomy for biliary pancreatitis. But, it should be emphasized that this was a restricted experimental study, and further clinical studies are needed to adopt these results into clinical settings.

Oxidative and nitrosative stress in acute pancreatitis. Modulation by pentoxifylline and oxypurinol

Reactive oxygen species are considered mediators of the inflammatory response and tissue damage in acute pancreatitis. We previously found that the combined treatment with oxypurinol - as inhibitor of xanthine oxidase- and pentoxifylline - as inhibitor of TNF-α production-restrained local and systemic inflammatory response and decreased mortality in experimental acute pancreatitis. Our aims were (1) to determine the time-course of glutathione depletion and oxidation in necrotizing pancreatitis in rats and its modulation by oxypurinol and pentoxifylline; (2) to determine whether TNF-α is responsible for glutathione depletion in acute pancreatitis; and (3) to elucidate the role of oxidative stress in the inflammatory cascade in pancreatic AR42J acinar cells. We report here that oxidative stress and nitrosative stress occur in pancreas and lung in acute pancreatitis and the co-treatment with oxypurinol and pentoxifylline prevents oxidative stress in both tissues. Oxypurinol was effective in preventing glutathione oxidation, whereas pentoxifylline abrogated glutathione depletion. This latter effect was independent of TNF-α since glutathione depletion occurred in mice deficient in TNF-α or its receptors after induction of pancreatitis. The beneficial effects of oxypurinol in the inflammatory response may also be ascribed to a partial inhibition of MEK1/2 activity. Pentoxifylline markedly reduced the expression of Icam1 and iNos induced by TNF-α in vitro in AR42J cells. Oxidative stress significantly contributes to the TNF-α-induced up-regulation of Icam and iNos in AR42J cells. These results provide new insights into the mechanism of action of oxypurinol and pentoxifylline as anti-inflammatory agents in acute pancreatitis.

Carotenoid deficiency in chronic pancreatitis: the effect of an increase in tomato consumption

BACKGROUND/OBJECTIVES

Carotenoids are potentially malabsorbed in patients with chronic pancreatitis (CP). The aims of this study were: (1) to determine the prevalence of low levels of each of the major carotenoids in subjects with CP; (2) to compare carotenoids in CP subjects with or without vascular disease and (3) to test the effect of an increase in dietary lycopene intake in patients with low plasma lycopene concentration.

SUBJECTS/METHODS

Simultaneous determination of carotenoids was done in 80 patients with CP and 20 healthy subjects, using high-performance liquid chromatography. Of the CP patients who had low lycopene concentration, 22 (<120 μg/l) had to consume daily 40 g tomato paste (approximately 24 mg lycopene).

RESULTS

Of these patients, 84.7% had at least one carotenoid deficiency and 27.5% had more than four carotenoid deficiencies. Low plasma concentrations in β-carotene and lycopene were correlated, in CP group, with a low body mass index (BMI), a low low-density lipoprotein (LDL) cholesterol concentration, alcohol consumption and current smoking status, whereas low plasma concentration in β-cryptoxanthine was correlated with a low BMI, a low LDL cholesterol concentration and alcohol consumption. Lycopene concentration was decreased in patients with vascular disease (171±197 vs 99±72 μg/l; P=0.02). After an intervention period of 8±2 months, lycopene concentration increased from 67.5±30 to 121.8±102 μg/l (P=0.025).

CONCLUSION

Carotenoid concentrations are dramatically decreased in CP, especially lycopene in CP patients with vascular disease. Despite malabsorption, it is possible to increase lycopene plasma concentration by increasing heated tomato consumption.

Heme oxygenase-1 as a therapeutic target in inflammatory disorders of the gastrointestinal tract

Heme oxygenase (HO)-1 is the inducible isoform of the first and rate-limiting enzyme of heme degradation. HO-1 not only protects against oxidative stress and apoptosis, but has received a great deal of attention in recent years because of its potent anti-inflammatory functions. Studies with HO-1 knockout animal models have led to major advances in the understanding of how HO-1 might regulate inflammatory immune responses, although little is known on the underlying mechanisms. Due to its beneficial effects the targeted induction of this enzyme is considered to have major therapeutic potential for the treatment of inflammatory disorders. This review discusses current knowledge on the mechanisms that mediate anti-inflammatory protection by HO-1. More specifically, the article deals with the role of HO-1 in the pathophysiology of viral hepatitis, inflammatory bowel disease, and pancreatitis. The effects of specific HO-1 modulation as a potential therapeutic strategy in experimental cell culture and animal models of these gastrointestinal disorders are summarized. In conclusion, targeted regulation of HO-1 holds major promise for future clinical interventions in inflammatory diseases of the gastrointestinal tract.

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

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

Melatonin ameliorates cerulein-induced pancreatitis by the modulation of nuclear erythroid 2-related factor 2 and nuclear factor-kappaB in rats

Melatonin exhibits a wide variety of biological effects, including antioxidant and anti-inflammatory functions. Its antioxidant role impedes the etiopathogenesis of pancreatitis, but little is known about the signaling pathway of melatonin in the induction of antioxidant enzymes in acute pancreatitis (AP). The aim of this study was to determine whether melatonin could prevent cerulein-induced AP through nuclear factor erythroid 2-related factor 2 (Nrf2) and curtail inflammation by inhibition of NF-kappaB. AP was induced by two intraperitoneal (i.p.) injections of cerulein at 2 h intervals (50 microg/kg) in Sprague-Dawley rats. Melatonin (10 or 50 mg/kg/daily, i.p.) was administered 24 h before each injection of cerulein. The rats were killed 12 h after the last injection. Acinar cell degeneration, pancreatic edema, and inflammatory infiltration were significantly different in cerulein- and melatonin-treated rats. Melatonin significantly reduced amylase, lipase, MPO, and MDA levels, and increased antioxidant enzyme activities including SOD and GPx, which were decreased in AP (P < 0.05). Melatonin increased the expression of NQO1, HO-1, and SOD2 when compared with the cerulein-induced AP group (P < 0.05). In addition, melatonin increased Nrf2 expression, and reduced expressions of tumor necrosis factor-alpha, IL-1beta, IL-6, IL-8, and iNOS. The elevated nuclear binding of NF-kappaB in the cerulein-induced pancreatitis group was inhibited by melatonin. These results show that melatonin increases antioxidant enzymes and Nrf2 expression, and limits inflammatory mediators in cerulein-induced AP. It is proposed that melatonin may play an important role in oxidative stress via the Nrf2 pathway in parallel with reduction of inflammation by NF-kappaB inhibition.

Melatonin modulates the severity of taurocholate-induced acute pancreatitis in the rat

The aim of this study was to investigate the effects of melatonin on serum amylase, tumor necrosis factor-alpha (TNF-alpha) and histological changes in rats with taurocholate-induced acute pancreatitis. Thirty male Wistar rats were randomly divided into three groups; group 1, group 2 and group 3 were enrolled as melatonin, control and sham groups, respectively (n = 10 per group). Acute pancreatitis was induced by 1 ml/kg body weight using 5% taurocholate injection into the biliopancreatic duct in groups 1 and 2 after clamping the hepatic duct. Those in group 1 received 50 mg/kg body weight melatonin by intraperitoneal (i.p.) injection. Group 2 received physiological saline i.p. at the same dose. Group 3 solely underwent laparotomy with cannulation of the biliopancreatic duct. Twenty-four hours after the intervention, the rats were killed, and serum samples were collected to measure amylase and TNF-alpha levels. Simultaneously, pancreatic tissues were removed, stained with hematoxylin-eosin and examined under a light microscope. Serum amylase and TNF-alpha levels were significantly lower in the melatonin group compared to the controls (P < 0.001). The total histological score, including edema, inflammation, perivascular infiltrate, acinar necrosis, fat necrosis and hemorrhage, was also significantly lower in the melatonin group as compared to the control (P < 0.0001). In conclusion, melatonin is potentially capable of reducing pancreatic damage by decreasing serum TNF-alpha levels in taurocholate-induced acute pancreatitis in rats. This result supports the idea that melatonin might be beneficial in ameliorating the severity of acute pancreatitis.

Therapeutic effect of caffeic acid phenethyl ester on cerulein-induced acute pancreatitis

AIM: To evaluate the therapeutic role of caffeic acid phenethyl ester (CAPE) in a rat model of cerulean-induced acute pancreatitis (AP).

METHODS: Seventy male Wistar albino rats were divided into seven groups. Acute edematous pancreatitis was induced by subcutaneous cerulein injection (20 μg/kg) four times at 1-h intervals. CAPE (30 mg/kg) was given by subcutaneous injection at the beginning (CAPE 1 group) and 12 h after the last cerulein injection (CAPE 2 group). Serum amylase, lipase, white blood cell count, and tumor necrosis factor (TNF)-α levels were measured, and pancreatic histopathology was assessed.

RESULTS: In the AP group, amylase and lipase levels were found to be elevated and the histopathological evaluation showed massive edema and inflammation of the pancreas, with less fatty necrosis when compared with sham and control groups. Amylase and lipase levels and edema formation decreased significantly in the CAPE therapy groups (P < 0001); especially in the CAPE 2 group, edema was improved nearly completely (P = 0001). Inflammation and fatty necrosis were partially recovered by CAPE treatment. The pathological results and amylase level in the placebo groups were similar to those in the AP group. White blood cell count and TNF-α concentration was nearly the same in the CAPE and placebo groups.

CONCLUSION: CAPE may be useful agent in treatment of AP but more experimental and clinical studies are needed to support our observation of beneficial effects of CAPE before clinical usage of this agent.

Antithrombin III prevents cerulein-induced acute pancreatitis in rats

OBJECTIVES

Systemic inflammatory mediators, including the protein high-mobility group box 1 (HMGB1), play an important role in the development of acute pancreatitis. Anticoagulants, such as antithrombin III (AT III), inhibit inflammation resulting from various causes, but their mechanism of action is not well understood. Because acute pancreatitis is a severe inflammatory disease, we hypothesized that AT III would inhibit inflammation and prevent cerulein-induced acute pancreatitis.

METHODS

Experimental animals received or were saline injected with a bolus of 250 IU/kg of AT III followed by intraperitoneal injections of 50 mg/kg of cerulein. Levels of cytokines (interleukin 6 and tumor necrosis factor alpha), nitric oxide (NO), and HMGB1 were measured in serum and pancreatic tissue at regular intervals for 12 hours after the cerulein injection.

RESULTS

Pancreas histopathology and wet-dry ratio significantly improved in the AT III-injected (250 IU/kg) animals compared with the saline-injected rats. Serum and pancreas HMGB1 levels decreased over time in AT III-treated animals. Antithrombin III also decreased cytokine, NO, and HMGB1 levels during cerulein-induced inflammation. As a result, AT III ameliorated the pathologic pancreas in the rat model of cerulein-induced acute pancreatitis.

CONCLUSIONS

Antithrombin III treatment inhibited the secretion of cytokines, NO, and HMGB1 and prevented cerulein-induced acute pancreatitis in the rat model.

Acute pancreatitis, bacterial translocation, and different octreotide regimens: an experimental study

PURPOSE

To determine the effect of octreotide, octreotide with zinc, levamisole, and misoprostol on the bacterial translocation that develops in rats with acute pancreatitis (AP).

METHODS

A total of 36 rats were divided into six groups, each consisting of six rats. Only laparotomy was performed on the first group. Acute pancreatitis was performed on the second group. Octreotide was given to the third, fourth, fifth, and sixth groups. Octreotide, octreotide with zinc, levamisole, and misoprostol were given to groups III, IV, V, VI, respectively. Rats were euthanized 48 h after the occurrence of AP. Blood and mesenteric lymph node samples were collected for polymerase chain reaction (PCR). Pancreatic tissue and terminal ileum were obtained for histopathological examinations.

RESULTS

The severity of pancreatitis and mucosal damage of the terminal ileum was higher in group II than groups I, III, IV, V, and VI, histopathologically (P < 0.05). There wasn't a significant difference with respect to OA with Zn or L or M and OA group (P > 0.05). A significant difference was found in PCR positivity in blood and mesenteric lymph node between groups I and II (P < 0.05).

CONCLUSIONS

In AP, administering octreotide alone significantly prevented the bacterial translocation by preventing mucosal damage. The zinc, levamisole, or misoprostol with octreotide did not influence the results.

Change of zinc, copper, and metallothionein concentrations and the copper-zinc superoxide dismutase activity in patients with pancreatitis

OBJECTIVES

The aims of the present studies were to measure the concentrations of zinc (Zn), copper (Cu), and metallothionein and the Cu/Zn superoxide dismutase activity as elements engaged in an essential manner in the prooxidative and antioxidative balance of organism and to demonstrate the degree to which metallothionein and Cu/Zn superoxide dismutase are involved in the inflammatory processes occurring in the pancreas.

METHODS

The concentration of metallothionein was measured by immunoenzymatic method. Serum Cu/Zn superoxide dismutase activity was determined using a commercial test. The measurements of Zn and Cu concentrations in serum were assessed with the use of flame atomic absorption spectrometry.

RESULTS

Lowered serum Zn concentration and higher Cu level were observed in the serum of patients with chronic exacerbated pancreatitis and chronic pancreatitis. The significant increase of metallothionein concentration and Cu/Zn superoxide dismutase activity was observed in the blood of patients with chronic exacerbated pancreatitis and chronic pancreatitis. In slices of the pancreas during pancreatitis, we observed in immunohistochemical reaction the variable involvement of Cu/Zn superoxide dismutase and metallothionein.

CONCLUSIONS

The results presented in these studies indicate an essential and variable involvement of antioxidants such Cu/Zn superoxide dismutase and metallothionein and disordered Cu and Zn homeostasis depending on the progression of inflammatory processes in patients with pancreatitis.

Effect of Korean red ginseng on superoxide dismutase inhibitor-induced pancreatitis in rats: a histopathologic and immunohistochemical study

OBJECTIVES

Korean red ginseng (KRG) is a representative herbal remedy in Korea. We examined the effects of KRG treatment on superoxide dismutase inhibitor-induced experimental pancreatitis.

METHODS

Sprague-Dawley rats and KRG from the roots of a 6-year-old fresh Panax ginseng C. A. Meyer plant were used in this study. Pancreatitis was induced by intraperitoneal injection of diethyldithiocarbamate for 4 weeks. Korean red ginseng was fed orally to rats for the next 3 weeks. At week 7, all rats were killed, and pancreatic tissues were analyzed.

RESULTS

No histological alterations were detected in the pancreata of normal and KRG control groups. Tissues from the non-KRG-treated pancreatitis group exhibited marked pancreatic damage including changes in histological architecture, acinar cell necrosis and degeneration, and cytoplasmic vacuolization. However, tissues from the KRG-treated pancreatitis group exhibited no cellular damage and had normal histological pancreatic architecture. Immunohistochemical examination revealed that the expressions of nuclear factor kappaB, tumor necrosis factor alpha, inducible nitric oxide synthase, and the oxidant stress markers, malondialdehyde and 4-hydroxynonenal, were significantly decreased in the KRG-treated pancreatitis group as compared with the non-KRG-treated pancreatitis group.

CONCLUSIONS

Our results suggest that KRG has antioxidant therapeutic effects on superoxide dismutase inhibitor-induced pancreatitis by inhibition of nuclear factor kappaB.

Calcium elevation in mitochondria is the main Ca2+ requirement for mitochondrial permeability transition pore (mPTP) opening

We have investigated in detail the role of intra-organelle Ca2+ content during induction of apoptosis by the oxidant menadione while changing and monitoring the Ca2+ load of endoplasmic reticulum (ER), mitochondria, and acidic organelles. Menadione causes production of reactive oxygen species, induction of oxidative stress, and subsequently apoptosis. In both pancreatic acinar and pancreatic tumor AR42J cells, menadione was found to induce repetitive cytosolic Ca2+ responses because of the release of Ca2+ from both ER and acidic stores. Ca2+ responses to menadione were accompanied by elevation of Ca2+ in mitochondria, mitochondrial depolarization, and mitochondrial permeability transition pore (mPTP) opening. Emptying of both the ER and acidic Ca2+ stores did not necessarily prevent menadione-induced apoptosis. High mitochondrial Ca2+ at the time of menadione application was the major factor determining cell fate. However, if mitochondria were prevented from loading with Ca2+ with 10 mum RU360, then caspase-9 activation did not occur irrespective of the content of other Ca2+ stores. These results were confirmed by ratiometric measurements of intramitochondrial Ca2+ with pericam. We conclude that elevated Ca2+ in mitochondria is the crucial factor in determining whether cells undergo oxidative stress-induced apoptosis.

Melatonin modulates the severity of taurocholate-induced acute pancreatitis in the rat

The aim of this study was to investigate the effects of melatonin on serum amylase, tumor necrosis factor-alpha (TNF-alpha) and histological changes in rats with taurocholate-induced acute pancreatitis. Thirty male Wistar rats were randomly divided into three groups; group 1, group 2 and group 3 were enrolled as melatonin, control and sham groups, respectively (n = 10 per group). Acute pancreatitis was induced by 1 ml/kg body weight using 5% taurocholate injection into the biliopancreatic duct in groups 1 and 2 after clamping the hepatic duct. Those in group 1 received 50 mg/kg body weight melatonin by intraperitoneal (i.p.) injection. Group 2 received physiological saline i.p. at the same dose. Group 3 solely underwent laparotomy with cannulation of the biliopancreatic duct. Twenty-four hours after the intervention, the rats were killed, and serum samples were collected to measure amylase and TNF-alpha levels. Simultaneously, pancreatic tissues were removed, stained with hematoxylin-eosin and examined under a light microscope. Serum amylase and TNF-alpha levels were significantly lower in the melatonin group compared to the controls (P < 0.001). The total histological score, including edema, inflammation, perivascular infiltrate, acinar necrosis, fat necrosis and hemorrhage, was also significantly lower in the melatonin group as compared to the control (P < 0.0001). In conclusion, melatonin is potentially capable of reducing pancreatic damage by decreasing serum TNF-alpha levels in taurocholate-induced acute pancreatitis in rats. This result supports the idea that melatonin might be beneficial in ameliorating the severity of acute pancreatitis.

Influence of acute pancreatitis on the in vitro responsiveness of rat mesenteric and pulmonary arteries

Background

Acute pancreatitis is an inflammatory disease characterized by local tissue injury and systemic inflammatory response leading to massive nitric oxide (NO) production and haemodynamic disturbances. Therefore, the aim of this work was to evaluate the vascular reactivity of pulmonary and mesenteric artery rings from rats submitted to experimental pancreatitis.

Male Wistar rats were divided into three groups: saline (SAL); tauracholate (TAU) and phospholipase A₂ (PLA₂). Pancreatitis was induced by administration of TAU or PLA₂ from Naja mocambique mocambique into the common bile duct of rats, and after 4 h of duct injection the animals were sacrificed. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP) and phenylephrine (PHE) in isolated mesenteric and pulmonary arteries were obtained. Potency (pEC₅₀) and maximal responses (E_MAX) were determined. Blood samples were collected for biochemical analysis.

Results

In mesenteric rings, the potency for ACh was significantly decreased from animals treated with TAU (about 4.2-fold) or PLA₂ (about 6.9-fold) compared to saline group without changes in the maximal responses. Neither pEC₅₀ nor E_MAX values for Ach were altered in pulmonary rings in any group. Similarly, the pEC₅₀ and the E_MAX values for SNP were not changed in both preparations in any group. The potency for PHE was significantly decreased in rat mesenteric and pulmonary rings from TAU group compared to SAL group (about 2.2- and 2.69-fold, for mesenteric and pulmonary rings, respectively). No changes were seen in the E_MAX for PHE. The nitrite/nitrate (NO_x^-) levels were markedly increased in animals submitted to acute pancreatitis as compared to SAL group, approximately 76 and 68% in TAU and PLA₂ protocol, respectively.

Conclusion

Acute pancreatitis provoked deleterious effects in endothelium-dependent relaxing response for ACh in mesenteric rings that were strongly associated with high plasma NO_x^- levels as consequence of intense inflammatory responses. Furthermore, the subsensitivity of contractile response to PHE in both mesenteric and pulmonary rings might be due to the complications of this pathological condition in the early stage of pancreatitis.

Pharmacological approach to acute pancreatitis

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

Comparative effects of several therapatic agents on hepatic damage induced by acute experimental pancreatitis

PURPOSE

The prognosis of acute pancreatitis (AP) depends upon the degree of pancreatic necrosis and the intensity of multisystem organ failure. The liver contributes to the systemic manifestations of AP by releasing some cytokines. This study was undertaken to examine comparative effects of melatonin, antioxidant mixture containing L(+)-ascorbic acid and N-acetyl cysteine, pentoxifylline and L-arginine on hepatic damage induced by caerulein-pancreatitis.

RESULTS

The liver specimens of all groups showed histopathological alterations such as hepatocyte necrosis, intracellular vacuolization, vascular congestion, sinusoidal dilatation and inflammatory infiltration. TEM studies revealed vacuole formation, mitochondrial degeneration, lysosome accumulation and necrosis. The mean histopathological score of the caerulein group was significantly different from that of each treatment group.

CONCLUSION

L-Arginine and antioxidant administration be important for reducing hepatic damage induced by AP. Improvement of hepatic damage, in turn, might be beneficial for the prognosis of AP.

Protective effect of inducible nitric oxide synthase inhibitor on pancreas transplantation in rats

AIM

To investigate the effect of inducible nitric oxide synthase inhibitor, aminoguanidine, on pancreas transplantation in rats.

METHODS

A model of pancreas transplantation was established in rats. Streptozotocin-induced diabetic male Wistar rats were randomly assigned to sham-operation control group (n = 6), transplant control group (n = 6), and aminoguanidine (AG) treatment group (n = 18). In the AG group, aminoguanidine was added to intravascular infusion as the onset of reperfusion at the dose of 60 mg/kg, 80 mg/kg, 100 mg/kg body weight, respectively. Serum nitric oxide (NO) level, blood sugar and amylase activity were detected. Nitric oxide synthase (NOS) test kit was used to detect the pancreas cNOS and inducible NOS (iNOS) activity. Pancreas sections stained with HE and immunohistochemistry were evaluated under a light microscope.

RESULTS

As compared with the transplant control group, the serum NO level and amylase activity decreased obviously and the evidence for pancreas injury was much less in the AG group. The AG (80 mg/kg body weight) group showed the most significant difference in NO and amylase (NO: 66.0 +/- 16.6 vs 192.3 +/- 60.0, P < 0.01 and amylase: 1426 +/- 177 vs 4477 +/- 630, P < 0.01). The expression and activity of tissue iNOS, and blood sugar in the AG (80 mg/kg body weight) group were much lower than those in the transplant control group (iNOS: 2.01 +/- 0.23 vs 26.59 +/- 5.78, P < 0.01 and blood sugar: 14.2 +/- 0.9 vs 16.8 +/- 1.1, P < 0.01).

CONCLUSION

Selective iNOS inhibitor, aminoguanidine as a free radical, has a protective effect on pancreas transplantation in rats by inhibiting NO and reducing its toxicity.

A cell-based approach to study changes in the pancreas following nicotine exposure in an animal model of injury

BACKGROUND

Cigarette smoking is a recognized risk factor for the induction of pancreatic diseases and is suspected to play a major role in the development of pancreatic cancer in smokers.

MATERIALS AND METHODS

This study was designed to characterize the mechanisms of nicotine-induced injury to the pancreas. AR42Jcells, a stable mutant pancreatic tumor cell line, was chosen for the study because of its stability in culture media and also because of its known secretory capacity, which is like that of a normal pancreatic acinar cell. It is hypothesized that nicotine-induced effects on the pancreas are triggered by oxidative stress induced in pancreatic acinar cell via oxidative stress signaling pathways.

RESULTS

The results from our study showed that, in vitro, nicotine induced generation of oxygen free radicals measured as malondialdehyde, an end product of lipid peroxidation. Treatment of AR42J cells with nicotine induced p-ERK 1/2 activation as confirmed by Western blot and immunofluorescence imaging of cytoplasmic localization of mitogen-activated protein kinase (MAPK) signals. Nicotine enhanced AR42J cell proliferation and cholecystokinin-stimulated amylase release in AR42J cells. These effects of nicotine were confirmed by simultaneous studies conducted on the same cells by hydrogen peroxide, a known oxidative biomarker. Allopurinol, a XOD inhibitor, suppressed these effects induced by nicotine and H(2)O(2) with the exception that cholecystokinin-stimulated amylase release by H(2)O(2) remained unaltered when AR42J cells were preincubated with allopurinol. These results suggest that nicotine-induced effects on pancreatic acinar cells were associated with generation of oxyradical mediated via the XOD pathway. The results have a direct impact on cell proliferation, MAPK signaling, and acinar cell function.

CONCLUSION

We conclude that nicotine induces oxidative stress in pancreatic acinar cells and that these events trigger pathophysiological changes in the pancreas, leading to increased cell proliferation and injury.

Methylene blue improves hemodynamic shock but increases lipoperoxidation in severe acute pancreatitis pig model

PURPOSE: Study hemodynamic pattern and lipoperoxidation during methylene blue (MB) treatment on taurocholate - enterokinase induced acute pancreatitis (AP). METHODS: Thirty pigs were equally divided in control group; MB group; AP group; MB previous AP group; and MB after 90 min of induced AP group. MB was given iv in a bolus dose (2mg.kg-1) followed by maintenance dose (2 mg.kg-1.h-1). Hemodynamic parameters were recorded continuously during 180 min by Swan-Ganz catheter. Blood samples were taken every 60 min to determine arterial and venous nitrate, malondialdehyde (MDA) and amylase. Pancreatic tissue was removed for histopathologic study. RESULTS: In AP group MBP and CO decreased over time 33% (p<0.05) and 52% (p<0.05), respectively. In MB previous induced-AP group, there was 70 minutes delay (p<0.05) to decrease MBP and CO. In MB group arterial and venous nitrite decreased (p<0.05) over time. MB infusion increased (p>0.05) serum MDA when associated to AP. After induced AP, MB did not reverse MBP and CO decrease. There was no difference in serum amylase and necro-hemorrhagic findings with MB treatment. CONCLUSIONS: In this taurocholate-induced AP model MB treatment delayed hemodynamic shock and decreases serum nitrate levels but increases serum MDA levels. No volemic replacement was done and it may have been a mitigated factor to a poor tissue perfusion and impairment microcirculation. Further investigations are needed to elucidate MB treatment role during AP treatment.

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

BACKGROUND

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

AIM OF THE STUDY

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

METHODS

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

RESULTS

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

CONCLUSION

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

Alleviation of cell damage in experimental ANP in rats by administration of chondroitin-sulfate reduces

In order to explore the effects of retrograde infusion of chondroitin-sulfate via the pancreatic duct on cytoprotection and attenuation of oxidative damage during acute necrotic pancreatitis (ANP), male Wistar rats were randomly divided into three groups: A, B (experimental groups) and C (sham operation, control group). The rats in group A was subjected to retrograde injection of 5% sodium taurocholate via the pancreatic duct, and those in group B received chondroitin-sulfate therapy after ANP induction. All rats in three groups were killed at 6 h. The levels of malondialdehyde (MAD), total superoxide dismutase (SOD), glutathione (GSH), adenosine triphosphate (ATP) and serum amylase (SAM) were measured. The morphologic changes in pancreatic tissues were observed. It was found that the level of SAM was increased in group A and group B, with corresponding pathological changes of ANP. The levels of ATP, GSH and SOD in group A were decreased markedly and MDN increased significantly as compared with those in group B (P<0.01). In group B, the histopathologic damage was attenuated to a certain extent in comparison to that in group A. It was concluded that endogenous antioxidants were significantly reduced and lipid peroxidation increased during ANP. Retrograde infusion of chondroitin-sulfate via pancreatic duct could alleviate the pancreatic cell damage as a sort of scavengers of oxygen free radicals.

Melatonin reduces apoptosis and necrosis induced by ischemia/reperfusion injury of the pancreas

The pancreas is highly susceptible to the oxidative stress induced by ischemia/reperfusion (IR) injury leading to the generation of acute pancreatitis. Melatonin has been shown to be useful in the prevention of the damage by ischemia-reperfusion in liver, brain, myocardium, gut and kidney. The aim of the study was to evaluate the cytoprotective properties of melatonin against injury induced by IR in pancreas. The obstruction of gastro-duodenal and inferior splenic arteries induced pancreatic IR in male Wistar rats. Melatonin was intraperitoneally administered before or/and after IR injury. The animals were killed at 24 and 48 hr after reperfusion and there were evaluated parameters of oxidative stress (lipoperoxides, superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione), glandular endocrine and exocrine function (lipase, amylase, insulin) and cell injury (apoptosis and necrosis). The IR induced a marked enhancement of oxidative stress and impaired pancreatic function. The histological analysis showed that IR induced acute pancreatitis with the accumulation of inflammatory infiltrate, disruption of tissue structure, cell necrosis and hemorrhage. Melatonin administration before or after pancreatic IR prevented all tissue markers of oxidative stress, biochemical and histological signs of apoptosis and necrosis, and restored glandular function. No histological signs of pancreatitis were observed 48 hr after reperfusion in 80% of the animals treated with melatonin, with only a mild edematous pancreatitis being observed in the remaining rats. Preventive or therapeutic administration of melatonin protected against the induction of oxidative stress and tissue injury, and restored cell function in experimental pancreatic IR in rats.