Oxygen free radicals in acute pancreatitis of the rat

Changes in cytokines and chemokines in an acute pancreatitis model

BACKGROUND

The immune response secondary to inflammation that develops in acute pancreatitis plays an important role in the clinical course of the disease. This study aims to evaluate the changes in various cytokines and chemokines according to the severity of pancreatitis.

METHODS

Twenty-one female Wistar albino rats were divided into three equal groups. The control group received no intervention. Intraperitoneal cerulein was administered to the other groups once per hour for five hours at doses of 50 µg/kg and 80 µg/kg for the mild and severe pancreatitis groups, respectively. The development of pancreatitis and its severity level were confirmed by histological evaluation after euthanization. Blood samples were taken from all rats to measure levels of Interleukin-10 (IL-10), Interferon gamma (IFN-γ), C-X-C Motif Chemokine Ligand 1 (CXCL-1), Monocyte Chemoattractant Protein-1 (MCP-1), Tumor Necrosis Factor alpha (TNF-α), Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF), IL-18, IL-12p70, IL-1β, IL-17A, IL-33, IL-1α, and IL-6. Additionally, the Schoenberg inflammation scores of pancreatic tissues were evaluated.

RESULTS

The acute pancreatitis model was successfully induced in all cases within the study groups, according to histopathological examination. It was found that the levels of CXCL-1, MCP-1, and IL-6 were statistically significantly higher in rats with pancreatitis, with these parameters being elevated in the group with severe pancreatitis. In correlation analyses, MCP-1 and IL-6 showed a moderate correlation with the severity of pancreatitis.

CONCLUSION

CXCL-1, MCP-1, and IL-6 exhibit predictive characteristics for the occurrence and clinical course of pancreatitis. Our results highlight the production and working pathways of these cytokines as potential targets for therapeutic intervention.

Glucocorticoid Treatment in Acute Respiratory Distress Syndrome: An Overview on Mechanistic Insights and Clinical Benefit

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS), triggered by various pathogenic factors inside and outside the lungs, leads to diffuse lung injury and can result in respiratory failure and death, which are typical clinical critical emergencies. Severe acute pancreatitis (SAP), which has a poor clinical prognosis, is one of the most common diseases that induces ARDS. When SAP causes the body to produce a storm of inflammatory factors and even causes sepsis, clinicians will face a two-way choice between anti-inflammatory and anti-infection objectives while considering the damaged intestinal barrier and respiratory failure, which undoubtedly increases the difficulty of the diagnosis and treatment of SAP-ALI/ARDS. For a long time, many studies have been devoted to applying glucocorticoids (GCs) to control the inflammatory response and prevent and treat sepsis and ALI/ARDS. However, the specific mechanism is not precise, the clinical efficacy is uneven, and the corresponding side effects are endless. This review discusses the mechanism of action, current clinical application status, effectiveness assessment, and side effects of GCs in the treatment of ALI/ARDS (especially the subtype caused by SAP).

Favorable efficacy of adalimumab treatment in experimental acute pancreatitis model

BACKGROUND

Acute pancreatitis is a clinical picture with a wide range of symptoms from mild inflammation to multiorgan failure and death. The aim of this study is to investigate the effects of Adalimumab (ADA) on inflammation and apoptosis in a cerulein-induced acute pancreatitis model in rats.

METHODS

Experimental cerulein-induced acute pancreatitis model was created by applying 4 intraperitoneal cerulein injections at 1-h intervals. A total of 40 rats, 8 in each group, were randomly distributed into five groups. In the groups that ADA treatment was given, two different doses of ADA were administered 5 mg/kg and 20 mg/kg as low and high doses, respectively. The rats were sacrificed 12 h after the last intraperitoneal administration of ADA. Blood samples were obtained from each rat for amylase, IL-6, and IL-1β measurements. Hematoxylin and Eosin (H&E) stains were used to undertake the histopathological analysis of the pancreas. The terminal deoxynucleotidyl transferase-mediated nick-end-labeling (TUNEL) method was used to evaluate apoptosis.

RESULTS

: Plasma amylase, IL-6, and IL-1β levels were significantly elevated in acute pancreatitis groups (p < 0.05). It was determined that both low (5 mg/kg) and high doses (20 mg/kg) of ADA ameliorated the parameters (plasma amylase, IL-6, and IL-1β) (p < 0.05). Although significant improvements were detected in the Schoenberg scoring system and the apoptotic index from the TUNEL method after highdose ADA treatment, no significant amelioration was observed in the histopathological examinations in the low-dose ADA group.

DISCUSSION

: It has been determined that the administration of high-dose ADA effectively alleviated the symptoms of acute pancreatitis and reduced the level of apoptosis. In line with the findings of our study, we have predicted that high-dose (20 mg/kg) ADA can be used as an effective and safe drug in the treatment of patients with acute pancreatitis.

Golimumab Ameliorates Pancreatic Inflammatory Response in the Cerulein-Induced Acute Pancreatitis in Rats

BACKGROUND

The aim of the study was to evaluate whether a new and successful treatment opportunity can be provided in acute pancreatitis and may prevent symptomatic treatments and show its effect through etiopathogenesis. Therefore, we want to investigate the efficacy of golimumab in an experimental rat model of cerulein-induced acute pancreatitis.

METHODS

A total of 35 rats, including 7 rats in each group, were distributed into 5 groups (sham, acute pancreatitis, placebo, acute pancreatitis+golimumab 5 mg/kg, and acute pancreatitis+golimumab 10 mg/kg). An experimental cerulein-induced acute pancreatitis model was accomplished by intraperitoneal cerulein injections. After sacrification, rat blood samples were collected for amylase, IL-6, and IL-1beta measurements. Histopathological analysis of the pancreas was performed with Tunel and hematoxylin and eosin staining.

RESULTS

Amylase, IL-6, and IL-1beta levels were found to be increased in the acute pancreatitis group. IL-1beta, amylase, IL-6 levels, and pancreatic inflammation were all significantly decreased in golimumab groups (P < .01). Moreover, in both golimumab groups, golimumab treatment significantly reduced apoptosis in pancreatic tissues (P < .05). Golimumab treatment was found to significantly reduce edema formation, inflammation, vacuolization, and fat necrosis of pancreatic tissues (P < .05).

CONCLUSION

Firstly in the literature, we investigated the efficacy of golimumab in the experimental acute pancreatitis model. In the light of our findings, it could be suggested that golimumab may be an effective and safe therapeutic option in the treatment of patients with acute pancreatitis.

Peripheral biomarkers of oxidative stress in dogs with acute pancreatitis

BACKGROUND

Oxidative stress is considered a pathomechanism of acute pancreatitis (AP), but no studies have extensively characterized oxidant status in dogs with naturally-occurring AP.

HYPOTHESIS OR OBJECTIVES

Evaluate measures of oxidant status in dogs with AP and explore whether these measures correlate with AP severity.

ANIMALS

Fifteen dogs with AP and 9 control dogs.

METHODS

Prospective, controlled observational study. Plasma reactive metabolite (RM) concentrations, antioxidant potential (AOP), and urinary F₂ isoprostane concentrations were measured in AP dogs and healthy controls. Severity of AP was assessed by length of hospitalization and 3 disease severity indices: canine acute pancreatitis severity (CAPS), modified canine activity index (M-CAI), and the acute patient physiologic and laboratory evaluation score (APPLE_full ).

RESULTS

Reactive metabolite (RM) concentrations (median, 65 relative fluorescent units [RFU]/μL; range, 20-331 RFU/μL) and RM:AOP (median, 7; range, 4-109) were higher in AP dogs than healthy controls (median RM, 25 RFU/μL; range, 16-41 RFU/μL; median RM:AOP, 4; range, 2-7; P < .001 for both comparisons). Reactive metabolite (r_S  = 0.603, P = .08) and RM:AOP (r_S  = 0.491, P = .06) were not correlated with the duration of hospitalization or disease severity indices evaluated. However, disease severity indices did not predict mortality in our study. Normalized urine 2,3-dinor-8-iso-prostaglandin F2α concentrations were correlated with C-reactive protein (CRP; r_S  = 0.491, P = .03), canine specific pancreatic lipase (Spec cPL; r_S  = 0.746, P = .002), and CAPS (r_S  = 0.603, P = .02).

CONCLUSIONS AND CLINICAL IMPORTANCE

Oxidant status is altered in dogs with naturally occurring AP, but the clinical relevance of this finding is unknown.

Protein kinase D: A therapeutic target in experimental alcoholic pancreatitis

BACKGROUND

Alcohol abuse, a main cause of pancreatitis, has been known to augment NF-κB activation and cell necrosis in pancreatitis. However, the underlying mechanisms are unclear. We recently reported that inhibition of protein kinase D (PKD) alleviated NF-κB activation and severity of experimental pancreatitis. Here we investigated whether PKD signaling mediated the modulatory effects of alcohol abuse on pathological responses in alcoholic pancreatitis.

METHODS

Alcoholic pancreatitis was provoked in two rodent models with pair-feeding control and ethanol-containing Lieber-DeCarli diets for up to 8 weeks followed by up to 7 hourly intraperitoneal injections of cerulein at 1 μg/kg (rats) or 3 μg/kg (mice). Effects of PKD inhibition by PKD inhibitors or genetic deletion of pancreatic PKD isoform (PKD3Δpanc mice) on alcoholic pancreatitis parameters were determined.

RESULTS

Ethanol administration amplified PKD signaling by promoting expression and activation of pancreatic PKD, resulted in augmented/promoted pancreatitis responses. Pharmacological inhibition of PKD or with PKD3Δpanc mice prevented the augmenting/sensitizing effect of ethanol on NF-κB activation and inflammatory responses, cell necrotic death and the severity of disease in alcoholic pancreatitis. PKD inhibition prevented alcohol-enhanced trypsinogen activation, mRNA expression of multiple inflammatory molecules, the receptor-interacting protein kinase activation, ATP depletion, and downregulation of pro-survival Bcl-2 protein in alcoholic pancreatitis. Furthermore, PKD inhibitor CID755673 or CRT0066101, administrated after the induction of pancreatitis in mouse and rat alcoholic pancreatitis models, significantly mitigated the severity of pancreatitis.

CONCLUSION

PKD mediates effect of alcohol abuse on pathological process of pancreatitis and constitutes a novel therapeutic target to treat this disease.

New insights into the etiology, risk factors, and pathogenesis of pancreatitis in dogs: Potential impacts on clinical practice

While most cases of pancreatitis in dogs are thought to be idiopathic, potential risk factors are identified. In this article we provide a state‐of‐the‐art overview of suspected risk factors for pancreatitis in dogs, allowing for improved awareness and detection of potential dog‐specific risk factors, which might guide the development of disease prevention strategies. Additionally, we review important advances in our understanding of the pathophysiology of pancreatitis and potential areas for therapeutic manipulation based thereof. The outcome of pathophysiologic mechanisms and the development of clinical disease is dependent on the balance between stressors and protective mechanisms, which can be evaluated using the critical threshold theory.

Antioxidant Molecules Isolated from Edible Prostrate Knotweed: Rational Derivatization to Produce More Potent Molecules

Prostrate knotweed also called Polygonum aviculare is an important edible plant. The polygonum is majorly known for the phenolics and antioxidants. The antioxidants combat the excessive free radicals within the body. The excessive free radicals are implicated in various other diseases like diabetes, Alzheimer's, and inflammation. This study was aimed at exploring the antioxidant bioactives and their derivatizations to produce new molecules with advanced pharmacological features. We have isolated six compounds (1–6) from Polygonum aviculare. Furthermore, rational-based chemical derivatives for compound 5 have been formed for the management of diabetes, Alzheimer's, and inflammation. In preliminary antioxidant studies, all the isolated compounds (1–6) showed potential results against DPPH and ABTS free radicals. Based on the IC₅₀ and chemical nature of the compounds, compound 5 was subjected to derivatization. Keeping the phenolic part of compound 5 unaffected, hydroxy succinimide (5A) and thiazolidinedione (5B) were synthesized. The compound 5A was found to be a potent inhibitor of AChE, BChE, COX-1, COX-2, 5-LOX, and DPPH giving IC₅₀ values of 10.60, 15.10, 13.91, 1.08, 0.71, and 1.05 μM, respectively. The COX-2 selectivity of compound 5A was found at 12.9. The compound 5B was found to be a potent multitarget antidiabetic agent giving IC₅₀ values of 15.34, 21.83, 53.28, and 1.94 μM against α-glucosidase, α-amylase, protein tyrosine phosphatase 1B, and DPPH. Docking studies were performed to manipulate the binding interactions. The docking pose of all the tested compounds was found to have increased binding affinity against all tested targets that supported the in vitro results. Our results showed that Polygonum aviculare is a rich source of antioxidant compounds. The two new derivatives have enhanced pharmacological features to treat diabetes, inflammation, and Alzheimer's disease.

Induction of pancreatitis in mice with susceptibility to pancreatic cancer

Chronic inflammation is known to be associated with pancreatic cancer, however a complete picture regarding how these pathologies intersect is still being characterized. In vivo model systems are critical for the study of mechanisms underlying how inflammation accelerates neoplasia. Repeat injection of cerulein, a cholecystokinin (CCK) analog, is widely used to experimentally induce acute and chronic pancreatitis in vivo. Chronic cerulein administration into genetically engineered mouse models (GEMMs) with predisposition to pancreatic cancer can induce a pro-inflammatory immune response, pancreatic acinar cell damage, pancreatic stellate cell activation, and accelerate the onset of neoplasia. Here we provide a detailed protocol and insights into using cerulein to induce pancreatitis in GEMMs, and methods to experimentally assess inflammation and pancreatic neoplasia.

Activity of Ligustrum vulgare L extracts against acute pancreatitis in murine models by regulation of p38 MAPK and NF-κB signaling pathways

Pancreatitis is a fatal disease associated with significant mortality and morbidity. At present, no specific treatment is available for pancreatitis and the patients are mainly treated with supportive medication. The need for specific antipancreatitic chemotherapy is an urgent medical obligation. In the current study, protective effects of the methanolic extract of the Ligustrum vulgare berries were investigated in the rat model of acute pancreatitis. Acute pancreatitis (AP) was induced in the male Sprague-Dawley (SD) rats by cerulein injection. Fruit extract of L. vulgare L extract was prepared using the methanol. Treatment effects of L. vulgare were evaluated in AP rats. Serum levels of lipase, amylase, proinflamatory cytokines (TNF-α, IL-6, TL-1β), lipid peroxidase (LPO), myeloperoxidase (MPO) were determined. Histological changes in the pancreas were assessed. L. vulgare treatment prevented the increase in serum amylase and lipase levels, reduced the disease progression in pancreas, and reduced the serum levels of tumour necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β in AP rats. Moreover, L. vulgare significantly suppressed pancreatic edema, inhibited oxidative damage (MPO activity and SOD activity), and inhibited the expression of NF-κB/p65 and activation (phosphorylation) of the inhibitor of NF-κB (IκBα) and p38 MAPKs. Histological examinations showed that L. vulgare significantly reduced the inflammatory and fibrotic changes. The results indicated the potent pancreato-protective effects of L. vulgare in AP.

Cyclic Voltammetry in Biological Samples: A Systematic Review of Methods and Techniques Applicable to Clinical Settings

Oxidative stress plays a pivotal role in the pathogenesis of many diseases, but there is no accurate measurement of oxidative stress or antioxidants that has utility in the clinical setting. Cyclic Voltammetry is an electrochemical technique that has been widely used for analyzing redox status in industrial and research settings. It has also recently been applied to assess the antioxidant status of in vivo biological samples. This systematic review identified 38 studies that used cyclic voltammetry to determine the change in antioxidant status in humans and animals. It focusses on the methods for sample preparation, processing and storage, experimental setup and techniques used to identify the antioxidants responsible for the voltammetric peaks. The aim is to provide key information to those intending to use cyclic voltammetry to measure antioxidants in biological samples in a clinical setting.

[Acute kidney injury following acute pancreatitis (AP-AKI): Definition, Pathophysiology, Diagnosis and Therapy]

Acute pancreatitis (AP) is the most frequent gastrointestinal cause for hospitalization and one of the leading causes of in-hospital deaths. Severe acute pancreatitis is often associated with multiorgan failure and especially with acute kidney injury (AKI). AKI can develop early or late in the course of the disease and is a strong determinator of outcome. The mortality in the case of dialysis-dependent AKI and acute pancreatitis raises exponentially in the affected patients. AP-induced AKI (AP-AKI) shows many similarities but also distinct differences to other causes of AKI occurring in the intensive care unit setting. The knowledge of the exact pathophysiology can help to adjust, control and improve therapeutic approaches to the disease. Unfortunately, there are only a few studies dealing with AP and AKI.In this review, we discuss recent data about pathogenesis, causes and management of AP-AKI in patients with severe acute pancreatitis and exploit in this regard the diagnostic and prognostic potential of respective newer serum and urine markers.

Pancreas-specific deletion of protein kinase D attenuates inflammation, necrosis, and severity of acute pancreatitis

BACKGROUND

Protein kinase D (PKD) family, which includes PKD/PKD1, PKD2, and PKD3, has been increasingly implicated in the regulation of multiple cellular functions and human diseases. We recently reported that pharmacologic inhibition of PKD ameliorated the pathologic responses and severity of pancreatitis. However, to further investigate the importance of PKD family members in pancreatitis, it is necessary to explore the effects of pancreas-specific genetic inhibition of PKD isoform on pathology of pancreatitis.

METHODS

We generated a mouse model (referred as PKD3Δpanc mice) with pancreas-specific deletion of PKD3, the predominant PKD isoform in mouse pancreatic acinar cells, by crossing Pkd3flox/flox mice with Pdx1-Cre transgenic mice which express Cre recombinase under the control of the mouse Pdx1 promoter. Pancreas-specific deletion of the PKD3 gene and PKD3 protein was confirmed by PCR and Western blot analysis. Experimental pancreatitis was induced in PKD3Δpanc and Pkd3flox/flox (control mice) littermates by intraperitoneal injections of cerulein or L-arginine.

RESULTS

Compared to the control mice, PKD3Δpanc mice displayed significant attenuation in inflammation, necrosis, and severity of pancreatitis in both experimental models. PKD3Δpanc mice had markedly decreased NF-κB and trypsinogen activation, pancreatic mRNA expression of multiple inflammatory molecules, and the receptor-interacting protein kinase 1 (RIP1) activation in pancreatitis. PKD3Δpanc mice also had less pancreatic ATP depletion, increased pro-survival Bcl-2 family protein expression, and autophagy promotion.

CONCLUSION

With PKD3Δpanc mouse model, we further demonstrated that PKD plays a critical role in pathobiological process of pancreatitis and PKD constitutes a novel therapeutic target to treat this disorder.

Docosahexaenoic acid inhibits zymogen activation by suppressing vacuolar ATPase activation in cerulein-stimulated pancreatic acinar cells

BACKGROUND

The premature activation of digestive enzyme zymogens within pancreatic acinar cells is an important early feature of acute pancreatitis. Supraphysiological concentrations of cholecystokinin (CCK) cause intrapancreatic zymogen activation and acute pancreatitis. Stimulation of vacuolar ATPase (vATPase) activity is required for zymogen activation in pancreatic acinar cells. Parkin, a multiprotein E3 ubiquitin ligase complex, promotes vATPase ubiquitination and degradation, which inhibits vATPase activity. Docosahexaenoic acid (DHA), an omega-3 fatty acid, exerts anti-inflammatory effects. It is reported to bind to G-protein coupled receptor 120 (GPR120) and GPR40. DHA induces the degradation of certain proteins by activating ubiquitin-proteasome system in various cells. This study aimed to investigate whether DHA induces Parkin and inhibits vATPase activity, resulting in zymogen inactivation in pancreatic acinar AR42J cells stimulated with cerulein, a CCK analog.

RESULTS

Cerulein induced the translocation of the cytosolic V1 domain (E subunit) of vATPase to the membrane, which indicated vATPase activation, and zymogen activation in AR42J cells. DHA suppressed the association of the vATPase with membranes, and zymogen activation (increased trypsin activity and amylase release) induced by cerulein. Pretreatment with a GPR120 antagonist AH-7614, a GPR40 antagonist DC260126, or an ubiquitination inhibitor PYR-41 reduced the effect of DHA on cerulein-induced zymogen activation. Treatment with PYR-41 reversed the DHA-induced decrease in vATPase activation in cerulein-treated cells. Furthermore, DHA increased the level of Parkin in membranes of cerulein-treated cells.

CONCLUSIONS

DHA upregulates Parkin which inhibits vATPase-mediated zymogen activation, via GPR120 and GPR40, in cerulein-stimulated pancreatic acinar cells.

Susceptibility Factors and Cellular Mechanisms Underlying Alcoholic Pancreatitis

Alcohol is a major cause of acute and chronic pancreatitis. There have been some recent advances in the understanding of the mechanisms underlying alcoholic pancreatitis, which include perturbation in mitochondrial function and autophagy and ectopic exocytosis, with some of these cellular events involving membrane fusion soluble N-ethylmaleimide-sensitive factor receptor protein receptor proteins. Although new insights have been unraveled recently, the precise mechanisms remain complex, and their finer details have yet to be established. The overall pathophysiology of pancreatitis involves not only the pancreatic acinar cells but also the stellate cells and duct cells. Why only some are more susceptible to pancreatitis and with increased severity, while others are not, would suggest that there may be undefined protective factors or mechanisms that enhance recovery and regeneration after injury. Furthermore, there are confounding influences of lifestyle factors such as smoking and diet, and genetic background. Whereas alcohol and smoking cessation and a generally healthy lifestyle are intuitively the advice given to these patients afflicted with alcoholic pancreatitis in order to reduce disease recurrence and progression, there is as yet no specific treatment. A more complete understanding of the pathogenesis of pancreatitis from which novel therapeutic targets could be identified will have a great impact, particularly with the stubbornly high fatality (>30%) of severe pancreatitis. This review focuses on the susceptibility factors and underlying cellular mechanisms of alcohol injury on the exocrine pancreas.

Examination of protective and therapeutic effects of ruscogenin on cerulein-induced experimental acute pancreatitis in rats

Purpose

To determine the potential protective and therapeutic effects and action mechanism of ruscogenin on cerulein-induced acute pancreatitis (AP) model in rats.

Methods

Overall, 32 rats were attenuated to the sham (2-mL/kg/day isotonic solution for 4 weeks), control (20-µg/kg cerulein-induced AP for 12 hours), prophylaxis groups (cerulein-induced AP following 3-mL/kg/day ruscogenin for 4 weeks) and treatment (3-mL/kg/day ruscogenin following cerulein-induced AP for 12 hours). Blood samples were collected for biochemical analysis of nitric oxide synthase 1 (NOS1/neuronal NOS), malondialdehyde (MDA) and intercellular adhesion molecule 1 (ICAM-1). After sacrification, pancreas tissues were collected and prepared for light microscopic (hematoxylin and eosin), immunohistochemical (nuclear factor kappa B) and biochemical analysis (tumor necrosis factor-alpha [TNF-α], interleukin-6 and 1β [IL-6 and IL-1β], CRP, high-sensitivity CRP [hs-CRP] amylase, lipase, and ICAM-1). Ultrastructural analysis was performed by transmission electron microscopy.

Results

The protective and therapeutic actions of ruscogenin were accomplished by improvements in histopathology, by decreasing blood cytokine levels of CRP, hs-CRP levels, TNF-α, IL-6, IL-1β, ICAM-1, by reducing the pancreatic enzymes amylase and lipase in blood, and by suppressing the expression of nuclear factor kappa B, ICAM-1, and NOS-1, but not MDA in pancreatic tissues. Ruscogenin also improved cerulein-induced ultrastructural degenerations in endocrine and exocrine cells, especially in treatment group.

Conclusion

The present findings have demonstrated the beneficial protective and therapeutical effects of ruscogenin, nominating it as a highly promising supplementary agent to be considered in the treatment of AP, and even as a protective agent against the damages induced by disease.

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

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

Antioxidant Defense, Oxidative Modification, and Salivary Gland Function in an Early Phase of Cerulein Pancreatitis

Acute pancreatitis (AP) is a multifactorial disease characterized by necroinflammatory changes of the pancreas. Our study is the first study which evaluated the relationship between the free radical production, enzymatic and nonenzymatic antioxidants, oxidative damage, and secretory function of the salivary glands of AP rats. Male Wistar rats were divided equally into 2 groups: control (n = 9) and AP (n = 9). AP was induced by intraperitoneal injection with cerulein and confirmed by higher serum amylase and lipase. We have demonstrated that the superoxide dismutase and glutathione reductase activities, as well as reduced glutathione concentration, were significantly decreased in both the parotid and submandibular glands of AP rats as compared to the control rats. The production of free radicals evidenced as dichlorodihydrofluorescein assay and the activity of NADPH oxidase and xanthine oxidase and IL-1β concentration were significantly higher in the parotid and submandibular glands of AP rats compared to the controls. In AP rats, we also showed a statistical increase in oxidation modification products (advanced glycation end products and advanced oxidation protein products), salivary amylase activity, and significant decrease in the total protein content. However, we did not show apoptosis and any morphological changes in the histological examination of the salivary glands of AP rats. To sum up, cerulein-induced AP intensifies production of oxygen free radicals, impairs the redox balance of the salivary glands, and is responsible for higher oxidative damage to these glands. Interestingly, oxidative modification of proteins and dysfunction of the antioxidant barrier are more pronounced in the submandibular glands of AP rats.

Dynamic thiol/disulphide homeostasis in acute pancreatitis

BACKGROUND/AIMS

The dynamic thiol/disulfide homeostasis plays pivotal roles in many physiological mechanisms in an organism. We aimed to investigate whether dynamic thiol/disulfide homeostasis changes among patients with acute pancreatitis.

MATERIALS AND METHODS

This prospective trial contained 45 patients with acute pancreatitis and 45 sex-and age-matched healthy volunteers as control group. Thiol/disulfide homeostasis parameters were measured by a novel and automated assay, and detected results were compared between the two groups.

RESULTS

Disulfide/total thiol percent ratio and disulfide/native thiol percent ratios were significantly higher in acute pancreatitis group; besides the native thiol, total thiol levels and native thiol/total thiol percent ratios were significantly lower (for all p < 0.001).

CONCLUSION

The thiol/disulfide homeostasis is impaired in acute pancreatitis with a shift toward the oxidative status, and this deficiency might be a pathogenic factor in acute pancreatitis. The correction of this thiol/disulfide imbalance may be a new target in the management of acute pancreatitis.

Novel Small Molecule Inhibitors of Protein Kinase D Suppress NF-kappaB Activation and Attenuate the Severity of Rat Cerulein Pancreatitis

Nuclear factor-kappa B (NF-κB) activation is a key early signal regulating inflammatory and cell death responses in acute pancreatitis. Our previous in vitro studies with molecular approaches on AR42J cell showed that protein kinase D (PKD/PKD1) activation was required in NF-κB activation induced by cholecystokinin 8 (CCK) or carbachol (CCh) in pancreatic acinar cells. Recently developed small molecule PKD inhibitors, CID755673 and CRT0066101, provide potentially important pharmacological approaches to further investigate the effect of PKD in pancreatitis therapy. The aim of this study was to explore whether CID755673 and CRT0066101 block NF-κB activation with in vitro and in vivo models of experimental pancreatitis and whether the small molecule PKD inhibitors have therapeutic effects when given before or after the initiation of experimental pancreatitis. Freshly prepared pancreatic acini were incubated with CID755673 or CRT006101, followed by hyperstimulation with CCK or CCh. For in vivo experimental pancreatitis, rats were treated with intraperitoneal injection of CID755673 or CRT0066101 prior to or after administering cerulein or saline. PKD activation and NF-κB-DNA binding activity in nuclear extracts from pancreatic acini and tissue were measured. The effects of PKD inhibitors on pancreatitis responses were evaluated. Our results showed that both CID755673 or CRT0066101 selectively and specifically inhibited PKD without effects on related protein kinase Cs. Inhibition of PKD resulted in significantly attenuation of NF-κB activation in both in vitro and in vivo models of experimental pancreatitis. NF-κB inhibition by CID755673 was associated with decreased inflammatory responses and attenuated severity of the disease, which were indicated by less inflammatory cell infiltration, reduced pancreatic interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), decreased intrapancreatic trypsin activation, and alleviation in pancreatic necrosis, edema and vacuolization. Furthermore, PKD inhibitor CID755673, given after the initiation of pancreatitis in experimental rat model, significantly attenuated the severity of acute pancreatitis. Therapies for acute pancreatitis are limited. Our results indicate that small chemical PKD inhibitors have significant potential as therapeutic interventions by suppressing NF-κB activation.

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

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

Docosahexaenoic Acid Inhibits Cerulein-Induced Acute Pancreatitis in Rats

Oxidative stress is an important regulator in the pathogenesis of acute pancreatitis (AP). Reactive oxygen species induce activation of inflammatory cascades, inflammatory cell recruitment, and tissue damage. NF-κB regulates inflammatory cytokine gene expression, which induces an acute, edematous form of pancreatitis. Protein kinase C δ (PKCδ) activates NF-κB as shown in a mouse model of cerulein-induced AP. Docosahexaenoic acid (DHA), an ω-3 fatty acid, exerts anti-inflammatory and antioxidant effects in various cells and tissues. This study investigated whether DHA inhibits cerulein-induced AP in rats by assessing pancreatic edema, myeloperoxidase activity, levels of lipid peroxide and IL-6, activation of NF-κB and PKCδ, and by histologic observation. AP was induced by intraperitoneal injection (i.p.) of cerulein (50 μg/kg) every hour for 7 h. DHA (13 mg/kg) was administered i.p. for three days before AP induction. Pretreatment with DHA reduced cerulein-induced activation of NF-κB, PKCδ, and IL-6 in pancreatic tissues of rats. DHA suppressed pancreatic edema and decreased the abundance of lipid peroxide, myeloperoxidase activity, and inflammatory cell infiltration into the pancreatic tissues of cerulein-stimulated rats. Therefore, DHA may help prevent the development of pancreatitis by suppressing the activation of NF-κB and PKCδ, expression of IL-6, and oxidative damage to the pancreas.

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

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

Sulforaphane Protects Pancreatic Acinar Cell Injury by Modulating Nrf2-Mediated Oxidative Stress and NLRP3 Inflammatory Pathway

Acute pancreatitis (AP) is characterized by early activation of intra-acinar proteases followed by acinar cell death and inflammation. Cellular oxidative stress is a key mechanism underlying these pathological events. Sulforaphane (SFN) is a natural organosulfur antioxidant with undescribed effects on AP. Here we investigated modulatory effects of SFN on cellular oxidation and inflammation in AP. AP was induced by cerulean hyperstimulation in BALB/c mice. Treatment group received a single dose of 5 mg/kg SFN for 3 consecutive days before AP. We found that SFN administration attenuated pancreatic injury as evidenced by serum amylase, pancreatic edema, and myeloperoxidase, as well as by histological examination. SFN administration reverted AP-associated dysregulation of oxidative stress markers including pancreatic malondialdehyde and redox enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx). In acinar cells, SFN treatment upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) expression and Nrf2-regulated redox genes including quinoneoxidoreductase-1, heme oxidase-1, SOD1, and GPx1. In addition, SFN selectively suppressed cerulein-induced activation of the nucleotide-binding domain leucine-rich repeat containing family, pyrin domain-containing 3 (NLRP3) inflammasome, in parallel with reduced nuclear factor- (NF-) κB activation and modulated NF-κB-responsive cytokine expression. Together, our data suggested that SFN modulates Nrf2-mediated oxidative stress and NLRP3/NF-κB inflammatory pathways in acinar cells, thereby protecting against AP.

Antioxidant Effect of Ukrain Versus N-Acetylcysteine Against Acute Biliary Pancreatitis in An Experimental Rat Model

Purpose/Aim: Oxidative stress plays an important role in the pathogenesis of acute pancreatitis (AP). We compared the therapeutic effects of Ukrain (NSC 631570) and N-acetylcysteine (NAC) in rats with AP.

MATERIALS AND METHODS

Forty male Sprague Dawley rats were divided into four groups: controls; AP; AP with NAC; and AP with Ukrain. AP was induced via the ligation of the bile-pancreatic duct; drugs were administered intraperitoneally (i.p.) 30 min and 12 h after AP induction. Twenty-four hours after AP induction, animals were sacrificed and the pancreas was excised. Levels of malondialdehyde (MDA) and nitric oxide (NO), and activity levels of tumor necrosis factor (TNF)-α, and myeloperoxidase (MPO) were measured in tissue samples. Total oxidant status (TOS), total antioxidant status (TAS), and total bilirubin, as well as activity levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), amylase and lipase were measured in serum samples. Pancreatic tissue histopathology was also evaluated.

RESULTS

Test drugs reduced levels of MDA, NO, TNF-α, total bilirubin, AST, ALT, TOS and MPO, amylase and lipase activities (P < 0.001), and increased TAS (P < 0.001). Rats treated with test drugs attenuated AP-induced morphologic changes and decreased pancreatic damage scores compared with the AP group (P < 0.05). Both test drugs attenuated pancreatic damage, but the therapeutic effect was more pronounced in rats that received Ukrain than in those receiving NAC.

CONCLUSIONS

These results suggest that treatment with Ukrain or NAC can reduce pancreatic damage via anti-inflammatory and antioxidant effects.

Effects of Montelukast in an Experimental Model of Acute Pancreatitis

Background

We evaluated the hematological, biochemical, and histopathological effects of Montelukast on pancreatic damage in an experimental acute pancreatitis model created by cerulein in rats before and after the induction of pancreatitis.

Materials/Methods

Forty rats were divided into 4 groups with 10 rats each. The study groups were: the Cerulein (C) group, the Cerulein + early Montelukast (CMe) group, the Cerulein + late Montelukast (CMl) group, and the Control group. The pH, pO2, pCO2, HCO3, leukocyte, hematocrit, pancreatic amylase, and lipase values were measured in the arterial blood samples taken immediately before rats were killed.

Results

There were statistically significant differences between the C group and the Control group in the values of pancreatic amylase, lipase, blood leukocyte, hematocrit, pH, pO2, pCO2, HCO3, and pancreatic water content, and also in each of the values of edema, inflammation, vacuolization, necrosis, and total histopathological score (P<0.05). When the CMl group and C group were compared, no statistically significant differences were found in any parameter analyzed. When the CMe group was compared with the C group, pancreatic amylase, lipase, pH, PO2, pCO2, HCO3, pancreatic water content, histopathological edema, inflammation, and total histopathological score values were significantly different between the groups (P<0.05). Finally, when the CMe group and the Control group were compared, significant differences were found in all except 2 (leukocyte and pO2) parameters (P<0.05).

Conclusions

Leukotriene receptor antagonists used in the late phases of pancreatitis might not result in any benefit; however, when they are given in the early phases or prophylactically, they may decrease pancreatic damage.

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.

Antioxidant and Anti-Inflammatory Effects of Coenzyme Q10 on L-Arginine-Induced Acute Pancreatitis in Rat

This study was aimed at evaluating the protective effect of coenzyme Q10 on L-arginine-induced acute pancreatitis in rats regarding biomarkers and morphologic changes. Thirty-two male Sprague-Dawley rats were divided into 4 equal groups. Control group received intraperitoneal normal saline, while in sham and experimental groups 1 and 2 pancreatitis was induced with L-arginine. E1 and E2 groups were treated with a single dose of 100 and 200 mg/kg Q10, respectively. Serum lipase and amylase, along with pancreas IL-10, IL-1β, and TNF-α, were measured. For evaluation of oxidative stress, pancreatic superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), and myeloperoxidase (MPO) were assessed. Histopathological examination for morphologic investigation was conducted. Serum amylase and lipase, as well as TNF-α and IL-1β cytokines, reverted with administration of Q10 in consistence with dosage. In contrast, Q10 assisted in boosting of IL-10 with higher dosage (200 mg/kg). A similar pattern for oxidative stress markers was noticed. Both MDA and MPO levels declined with increased dosage, contrary to elevation of SOD and GSH. Histopathology was in favor of protective effects of Q10. Our findings proved the amelioration of pancreatic injury by Q10, which suggest the anti-inflammatory and antioxidant property of Q10 and its potential therapeutic role.

Unfeasible experimental model of normothermic hepatic ischemia and reperfusion in rats using the Pringle maneuver

BACKGROUND

The negative result of a research does not always indicate failure, and when the data do not permit a proper conclusion, or are contrary to the initial project, should not simply be discarded and archived.

AIM

To report failure after performing experimental model of liver ischemia and reperfusion normothermic, continuous or intermittent, in small animals aiming at the study of biochemical and histological parameters after postoperative recovery.

METHODS

Fifteen Wistar rats were divided into three groups of five animals each; all underwent surgery, the abdomen was sutured after the proposed procedures for each group and the animals were observed for 6 h or until they died, and then were reoperated. In Group 1, control (sham-operated): dissection of the hepatic hilum was performed; in Group 2: clamping of the hepatic hilum for 30 m; in Group 3: clamping of the hepatic hilum for 15 m, reperfusion for 5 m and another 15 m of clamping. Data from Groups 2 and 3 were compared with Student's t test.

RESULTS

All animals of Group 1 survived for 6 h. Two animals in Group 2 died before the 6 h needed to validate the experiment; two did not recover from anesthesia and one survived until the end. In Group 3, four animals died before the 6 h established and one of them survived the required time. Only one animal in Group 2 and one in Group 3 survived and were able to accomplish the study. There was no statistical significance when the results of Groups 2 and 3 were compared (p>0.05).

CONCLUSION

The death of six animals before the necessary period of observation turned the initial proposal of the experiment unfeasible.

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.

Pharmacologic therapy for acute pancreatitis

While conservative management such as fluid, bowel rest, and antibiotics is the mainstay of current acute pancreatitis management, there is a lot of promise in pharmacologic therapies that target various aspects of the pathogenesis of pancreatitis. Extensive review of preclinical studies, which include assessment of therapies such as anti-secretory agents, protease inhibitors, anti-inflammatory agents, and anti-oxidants are discussed. Many of these studies have shown therapeutic benefit and improved survival in experimental models. Based on available preclinical studies, we discuss potential novel targeted pharmacologic approaches that may offer promise in the treatment of acute pancreatitis. To date a variety of clinical studies have assessed the translational potential of animal model effective experimental therapies and have shown either failure or mixed results in human studies. Despite these discouraging clinical studies, there is a great clinical need and there exist several preclinical effective therapies that await investigation in patients. Better understanding of acute pancreatitis pathophysiology and lessons learned from past clinical studies are likely to offer a great foundation upon which to expand future therapies in 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.

A review of the molecular aspects of melatonin's anti-inflammatory actions: recent insights and new perspectives

Melatonin is a highly evolutionary conserved endogenous molecule that is mainly produced by the pineal gland, but also by other nonendocrine organs, of most mammals including man. In the recent years, a variety of anti-inflammatory and antioxidant effects have been observed when melatonin is applied exogenously under both in vivo and in vitro conditions. A number of studies suggest that this indole may exert its anti-inflammatory effects through the regulation of different molecular pathways. It has been documented that melatonin inhibits the expression of the isoforms of inducible nitric oxide synthase and cyclooxygenase and limits the production of excessive amounts of nitric oxide, prostanoids, and leukotrienes, as well as other mediators of the inflammatory process such as cytokines, chemokines, and adhesion molecules. Melatonin's anti-inflammatory effects are related to the modulation of a number of transcription factors such as nuclear factor kappa B, hypoxia-inducible factor, nuclear factor erythroid 2-related factor 2, and others. Melatonin's effects on the DNA-binding capacity of transcription factors may be regulated through the inhibition of protein kinases involved in signal transduction, such as mitogen-activated protein kinases. This review summarizes recent research data focusing on the modulation of the expression of different inflammatory mediators by melatonin and the effects on cell signaling pathways responsible for the indole's anti-inflammatory activity. Although there are a numerous published reports that have analyzed melatonin's anti-inflammatory properties, further studies are necessary to elucidate its complex regulatory mechanisms in different cellular types and tissues.

Involvement of inflammatory factors in pancreatic carcinogenesis and preventive effects of anti-inflammatory agents

Chronic inflammation is known to be a risk for many cancers, including pancreatic cancer. Heavy alcohol drinking and cigarette smoking are major causes of pancreatitis, and epidemiological studies have shown that smoking and chronic pancreatitis are risk factors for pancreatic cancer. Meanwhile, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) are elevated in pancreatitis and pancreatic cancer tissues in humans and in animal models. Selective inhibitors of iNOS and COX-2 suppress pancreatic cancer development in a chemical carcinogenesis model of hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). In addition, hyperlipidemia, obesity, and type II diabetes are also suggested to be associated with chronic inflammation in the pancreas and involved in pancreatic cancer development. We have shown that a high-fat diet increased pancreatic cancer development in BOP-treated hamsters, along with aggravation of hyperlipidemia, severe fatty infiltration, and increased expression of adipokines and inflammatory factors in the pancreas. Of note, fatty pancreas has been observed in obese and/or diabetic cases in humans. Preventive effects of anti-hyperlipidemic/anti-diabetic agents on pancreatic cancer have also been shown in humans and animals. Taking this evidence into consideration, modulation of inflammatory factors by anti-inflammatory agents will provide useful data for prevention of pancreatic cancer.

Role of janus kinase/signal transducers and activators of transcription in the pathogenesis of pancreatitis and pancreatic cancer

In the pathogenesis of pancreatitis, oxidative stress is involved in the activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway and cytokine expression. High serum levels of cholecystokinin (CCK) have been reported in patients with acute pancreatitis, and treatment with cerulein, a CCK analogue, induces acute pancreatitis in a rodent model. Recent studies have shown that cerulein-activated nicotinamide adenine dinucleotide phosphate oxidase elicits reactive oxygen species, which trigger the phosphorylation of the JAK1, STAT1, and STAT3 proteins and induce the production of inflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL)-1β, and IL-6, in pancreatic acinar cells. The JAK/STAT pathway also stimulates cell proliferation and malignant transformation and inhibits apoptosis in the pancreas. This review discusses the possible role of the JAK/STAT pathway in the pathogenesis of pancreatitis and pancreatic cancer in response to oxidative stress.

Protein kinase d regulates cell death pathways in experimental pancreatitis

Inflammation and acinar cell necrosis are two major pathological responses of acute pancreatitis, a serious disorder with no current therapies directed to its molecular pathogenesis. Serine/threonine protein kinase D family, which includes PKD/PKD1, PKD2, and PKD3, has been increasingly implicated in the regulation of multiple physiological and pathophysiological effects. We recently reported that PKD/PKD1, the predominant PKD isoform expressed in rat pancreatic acinar cells, mediates early events of pancreatitis including NF-κB activation and inappropriate intracellular digestive enzyme activation. In current studies, we investigated the role and mechanisms of PKD/PKD1 in the regulation of necrosis in pancreatic acinar cells by using two novel small molecule PKD inhibitors CID755673 and CRT0066101 and molecular approaches in in vitro and in vivo experimental models of acute pancreatitis. Our results demonstrated that both CID755673 and CRT0066101 are PKD-specific inhibitors and that PKD/PKD1 inhibition by either the chemical inhibitors or specific PKD/PKD1 siRNAs attenuated necrosis while promoting apoptosis induced by pathological doses of cholecystokinin-octapeptide (CCK) in pancreatic acinar cells. Conversely, up-regulation of PKD expression in pancreatic acinar cells increased necrosis and decreased apoptosis. We further showed that PKD/PKD1 regulated several key cell death signals including inhibitors of apoptotic proteins, caspases, receptor-interacting protein kinase 1 to promote necrosis. PKD/PKD1 inhibition by CID755673 significantly ameliorated necrosis and severity of pancreatitis in an in vivo experimental model of acute pancreatitis. Thus, our studies indicate that PKD/PKD1 is a key mediator of necrosis in acute pancreatitis and that PKD/PKD1 may represent a potential therapeutic target in acute pancreatitis.

Sesamol attenuates oxidative stress–mediated experimental acute pancreatitis in rats

Acute pancreatitis is a potentially fatal disease with no known cure. The initial events in acute pancreatitis may occur within the acinar cells. We examined the effect of sesamol on (i) a cerulein-induced pancreatic acinar cancer cell line, AR42J, and (ii) cerulein-induced experimental acute pancreatitis in rats. Sesamol inhibited amylase activity and increased cell survival. It also inhibited medium lipid peroxidation and 8-hydroxydeoxyguanosine in AR42J cells compared with the cerulein-alone groups. In addition, in cerulein-treated rats, sesamol inhibited serum amylase and lipase levels, pancreatic edema, and lipid peroxidation, but it increased pancreatic glutathione and nitric oxide levels. Thus, we hypothesize that sesamol attenuates cerulein-induced experimental acute pancreatitis by inhibiting the pancreatic acinar cell death associated with oxidative stress in rats.

Tauroursodeoxycholic acid reduces endoplasmic reticulum stress, acinar cell damage, and systemic inflammation in acute pancreatitis

In acute pancreatitis, endoplasmic reticulum (ER) stress prompts an accumulation of malfolded proteins inside the ER, initiating the unfolded protein response (UPR). Because the ER chaperone tauroursodeoxycholic acid (TUDCA) is known to inhibit the UPR in vitro, this study examined the in vivo effects of TUDCA in an acute experimental pancreatitis model. Acute pancreatitis was induced in Wistar rats using caerulein, with or without prior TUDCA treatment. UPR components were analyzed, including chaperone binding protein (BiP), phosphorylated protein kinase-like ER kinase (pPERK), X-box binding protein (XBP)-1, phosphorylated c-Jun NH(2)-terminal kinase (pJNK), CCAAT/enhancer binding protein homologues protein, and caspase 12 and 3 activation. In addition, pancreatitis biomarkers were measured, such as serum amylase, trypsin activation, edema formation, histology, and the inflammatory reaction in pancreatic and lung tissue. TUDCA treatment reduced intracellular trypsin activation, edema formation, and cell damage, while leaving amylase levels unaltered. The activation of myeloperoxidase was clearly reduced in pancreas and lung. Furthermore, TUDCA prevented caerulein-induced BiP upregulation, reduced XBP-1 splicing, and caspase 12 and 3 activation. It accelerated the downregulation of pJNK. In controls without pancreatitis, TUDCA showed cytoprotective effects including pPERK signaling and activation of downstream targets. We concluded that ER stress responses activated in acute pancreatitis are grossly attenuated by TUDCA. The chaperone reduced the UPR and inhibited ER stress-associated proapoptotic pathways. TUDCA has a cytoprotective potential in the exocrine pancreas. These data hint at new perspectives for an employment of chemical chaperones, such as TUDCA, in prevention of acute pancreatitis.

Inhibitory mechanism of lycopene on cytokine expression in experimental pancreatitis

Reactive oxygen species (ROS) are important mediators to induce pancreatitis. Serum levels of antioxidant enzymes and carotenoids including lycopene are lower in patients with pancreatitis than those of healthy subjects. The cholecystokinin (CCK) analog cerulein induces similar pathologic events as shown in human pancreatitis. Recent studies show that high doses of cerulein activate NF-κB and induce the expression of inflammatory cytokines, in pancreatic acinar cells, which is mediated by the activation of NADPH oxidase. Lycopene functions as a very potent antioxidant to suppress the induction of inflammatory cytokines, in pancreatic acinar cells stimulated with cerulein. In this review, the possible beneficial effect of lycopene on experimental pancreatitis shall be discussed based on its antioxidant activity.

Potential role of NADPH oxidase-mediated activation of Jak2/Stat3 and mitogen-activated protein kinases and expression of TGF-β1 in the pathophysiology of acute pancreatitis

OBJECTIVE

NADPH oxidase is potentially associated with acute pancreatitis by producing reactive oxygen species (ROS). We investigated whether NADPH oxidase mediates the activation of Janus kinase (Jak)2/signal transducers and activators of transcription (Stat)3 and mitogen-activated protein kinases (MAPKs) to induce the expression of transforming growth factor-β1 (TGF-β1) in cerulein-stimulated pancreatic acinar cells.

TREATMENT

AR42J cells were treated with an NADPH oxidase inhibitor diphenyleneiodonium (DPI) or a Jak2 inhibitor AG490. Other cells were transfected with antisense or sense oligonucleotides (AS or S ODNs) for NADPH oxidase subunit p22(phox) or p47(phox).

METHODS

TGF-β1 was determined by enzyme-linked immonosorbent assay. STAT3-DNA binding activity was measured by electrophoretic mobility shift assay. Levels of MAPKs as well as total and phospho-specific forms of Jak1/Stat3 were assessed by Western blot analysis.

RESULTS

Cerulein induced increases in TGF-β1, Stat3-DNA binding activity and the activation of MAPKs in AR42J cells. AG490 suppressed these cerulein-induced changes, similar to inhibition by DPI. Cerulein-induced activation of Jak2/Stat3 and increases in MAPKs and TGF-β1 levels were inhibited in the cells transfected with AS ODN for p22(phox) and p47(phox) compared to S ODN controls.

CONCLUSION

Inhibition of NADPH oxidase may be beneficial for prevention and treatment of pancreatitis by suppressing Jak2/Stat3 and MAPKs and expression of TGF-β1 in pancreatic acinar cells.

Lycopene inhibits IL-6 expression in cerulein-stimulated pancreatic acinar cells

Reactive oxygen species (ROS) are known to be involved in the pathogenesis of acute and chronic pancreatitis. The cholecystokinin (CCK) analog cerulein causes pathophysiological, morphological, and biochemical events similar to those observed in human acute pancreatitis. The oxidant-sensitive transcription factor NF-κB plays a critical role in the development of cerulein pancreatitis by regulating the expression of pro-inflammatory cytokines in the pancreas. Lycopene has an anti-oxidant effect in various cells. In the present study, we investigated whether cerulein induces NF-κB activation and IL-6 expression in pancreatic acinar cells and whether lycopene inhibits these events. NF-κB-DNA-binding activity was determined by electrophoretic mobility shift assay, and mRNA expression was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR analyses. The IL-6 concentration in the medium was determined by enzyme-linked immunosorbent assay. Our results showed that cerulein induced IL-6 expression in a time-dependent manner. NF-κB-DNA-binding activity and intracellular levels of ROS in pancreatic acinar cells were increased by cerulein. Lycopene inhibited the cerulein-induced increase in intracellular ROS, NF-κB activation, and IL-6 expression in pancreatic acinar cells in a dose-dependent manner. In conclusion, lycopene may be beneficial in the prevention and/or treatment of acute pancreatitis by inhibiting the activation of NF-κB and the expression of inflammatory cytokines through reduction in intracellular levels of ROS in pancreatic acinar cells.

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.

Altered gene expression in cerulein-stimulated pancreatic acinar cells: pathologic mechanism of acute pancreatitis

Acute pancreatitis is a multifactorial disease associated with the premature activation of digestive enzymes. The genes expressed in pancreatic acinar cells determine the severity of the disease. The present study determined the differentially expressed genes in pancreatic acinar cells treated with cerulein as an in vitro model of acute pancreatitis. Pancreatic acinar AR42J cells were stimulated with 10(-8) M cerulein for 4 h, and genes with altered expression were identified using a cDNA microarray for 4,000 rat genes and validated by real-time PCR. These genes showed a 2.5-fold or higher increase with cerulein: lithostatin, guanylate cyclase, myosin light chain kinase 2, cathepsin C, progestin-induced protein, and pancreatic trypsin 2. Stathin 1 and ribosomal protein S13 showed a 2.5-fold or higher decreases in expression. Real-time PCR analysis showed time-dependent alterations of these genes. Using commercially available antibodies specific for guanylate cyclase, myosin light chain kinase 2, and cathepsin C, a time-dependent increase in these proteins were observed by Western blotting. Thus, disturbances in proliferation, differentiation, cytoskeleton arrangement, enzyme activity, and secretion may be underlying mechanisms 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.

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.

Inhibition of renin-angiotensin system in experimental acute pancreatitis in rats: a new therapeutic target?

OBJECTIVE

Pancreatic renin-angiotensin system has been implied to play a role in the regulation of pancreatic functions and could be a new therapeutic target in acute pancreatitis. The aim of this study was to evaluate the therapeutic potential of angiotensin-converting-enzyme inhibition by captopril and angiotensin II type 1 receptor inhibition by L-158809 and losartan experimentally in acute pancreatitis.

DESIGN

Rats were randomly divided into 15 groups. Acute edematous pancreatitis was induced by injection of cerulein 20microg/kg SC four times at hourly intervals. Severe necrotizing pancreatitis was induced by retrograde injection of 3% taurocholate into the biliary-pancreatic duct.

INTERVENTIONS

Captopril, L-158809 and losartan were given intraperitoneally. Main outcome features: pancreatic pathology, pancreatic myeloperoxidase activity and serum amylase activity were assessed.

RESULTS

Captopril decreased serum amylase (10,809+/-1867 vs. 4085+/-1028U/L, p<0.01), myeloperoxidase activity (3.5+/-0.5 vs. 1.5+/-0.1, p<0.05) and histopathological score (5.0+/-0.4 vs. 1.1+/-0.5, p<0.01) in acute edematous pancreatitis. In taurocholate induced severe necrotizing pancreatitis captopril ameliorated histopathological score (10.1+/-1.2 vs. 3.4+/-0.5, p<0.01), pancreatic parenchymal necrosis (4.5+/-0.6 vs. 0.0+/-0.0, p<0.001), fatty necrosis (2.8+/-0.9 vs. 0.1+/-0.1, p<0.01) and edema (2.1+/-0.3 vs. 1.4+/-0.3, p<0.05). However, L-158809 did not have similar beneficial effects on acute pancreatitis in rats while losartan decreased pancreatic parenchymal necrosis and neutrophil infiltration.

CONCLUSIONS

This study not only demonstrated the differential effects of captopril, losartan and L-158809 in acute pancreatitis but also showed that there is still much to investigate about pancreatic renin-angiotensin system. Inhibition of angiotensin-converting enzyme should be evaluated carefully as a potential new therapeutic target in acute pancreatitis.