Inducible nitric oxide synthase-deficient mice exhibit resistance to the acute pancreatitis induced by cerulein

Application of nanotechnology in the diagnosis and treatment of acute pancreatitis

Acute pancreatitis (AP) is a common digestive system disease. The severity of AP ranges from mild edema in the pancreas to severe systemic inflammatory responses leading to peripancreatic/pancreatic necrosis, multi-organ failure and death. Improving the sensitivity of AP diagnosis and developing alternatives to traditional methods to treat AP have gained the attention of researchers. With the continuous rise of nanotechnology, it is being widely used in daily life, biomedicine, chemical energy and many other fields. Studies have demonstrated the effectiveness of nanotechnology in the diagnosis and treatment of AP. Nanotechnology has the advantages of simplicity, rapidity and sensitivity in detecting biomarkers of AP, as well as enhancing imaging, which helps in the early diagnosis of AP. On the other hand, nanoparticles (NPs) have oxidative stress inhibiting and anti-inflammatory effects, and can also be loaded with drugs as well as being used in anti-infection therapy, providing a new approach for the treatment of AP. In this article, we elaborate and summarize on the potential of nanoparticles for diagnostic and therapeutic applications in AP from the current reported literature and experimental results to provide useful guidelines for further research on the application of nanotechnology.

Polyethylene glycol 35 ameliorates pancreatic inflammatory response in cerulein-induced acute pancreatitis in rats

BACKGROUND

Acute pancreatitis (AP) is a sudden inflammatory process of the pancreas that may also involve surrounding tissues and/or remote organs. Inflammation and parenchymal cell death are common pathological features of this condition and determinants of disease severity. Polyethylene glycols (PEGs) are non-immunogenic, non-toxic water-soluble polymers widely used in biological, chemical, clinical and pharmaceutical settings.

AIM

To evaluate the protective effect of a 35-kDa molecular weight PEG (PEG35) on the pancreatic damage associated to cerulein-induced acute pancreatitis in vivo and in vitro.

METHODS

Wistar rats were assigned at random to a control group, a cerulein–induced AP group and a PEG35 treatment group. AP was induced by five hourly intraperitoneal injections of cerulein (50 μg/kg/bw), while the control animals received saline solution. PEG35 was administered intraperitoneally 10 minutes before each cerulein injection in a dose of 10 mg/kg. After AP induction, samples of pancreatic tissue and blood were collected for analysis. AR42J pancreatic acinar cells were treated with increasing concentrations of PEG35 prior to exposure with tumor necrosis factor α (TNFα), staurosporine or cerulein. The severity of AP was determined on the basis of plasma levels of lipase, lactate dehydrogenase activity, pancreatic edema and histological changes. To evaluate the extent of the inflammatory response, the gene expression of inflammation-associated markers was determined in the pancreas and in AR42J-treated cells. Inflammation-induced cell death was also measured in models of in vivo and in vitro pancreatic damage.

RESULTS

Administration of PEG35 significantly improved pancreatic damage through reduction on lipase levels and tissue edema in cerulein-induced AP rats. The increased associated inflammatory response caused by cerulein administration was attenuated by a decrease in the gene expression of inflammation-related cytokines and inducible nitric oxide synthase enzyme in the pancreas. In contrast, pancreatic tissue mRNA expression of interleukin 10 was markedly increased. PEG35 treatment also protected against inflammation-induced cell death by attenuating lactate dehydrogenase activity and modulating the pancreatic levels of apoptosis regulator protein BCL-2 in cerulein hyperstimulated rats. Furthermore, the activation of pro-inflammatory markers and inflammation-induced cell death in pancreatic acinar cells treated with TNFα, cerulein or staurosporine was significantly reduced by PEG35 treatment, in a dose-dependent manner.

CONCLUSION

PEG35 ameliorates pancreatic damage in cerulein-induced AP and AR42J-treated cells through the attenuation of the inflammatory response and associated cell death. PEG35 may be a valuable option in the management of 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.

Blockade of the trans-sulfuration pathway in acute pancreatitis due to nitration of cystathionine β-synthase

Acute pancreatitis is an inflammatory process of the pancreatic gland that may lead to dysregulation of the trans-sulfuration pathway. The aims of this work were firstly to study the methionine cycle as well as the trans-sulfuration pathway using metabolomic and proteomic approaches identifying the causes of this dysregulation in an experimental model of acute pancreatitis; and secondly to reveal the effects of S-adenosylmethionine administration on these pathways. Acute pancreatitis was induced by cerulein in mice, and a group of animals received S-adenosylmethionine treatment. Cerulein-induced acute pancreatitis rapidly caused marked depletion of methionine, S-adenosylmethionine, 5′-methylthioadenosine, cystathionine, cysteine, and glutathione levels in pancreas, but S-adenosylhomocysteine and homocysteine remained unchanged. Protein steady-state levels of S-adenosylhomocysteine-hydrolase and cystathionine gamma-lyase diminished but methylthioadenosine phosphorylase levels increased in pancreas with acute pancreatitis. Although cystathionine β-synthase protein levels did not change with acute pancreatitis, Nos2 mRNA and protein levels were markedly up-regulated and caused tyrosine nitration of cystathionine β-synthase in pancreas. S-adenosylmethionine administration enhanced Nos2 mRNA expression and cystathionine β-synthase nitration and triggered homocysteine accumulation in acute pancreatitis. Furthermore, S-adenosylmethionine administration promoted enrichment of the euchromatin marker H3K4me3 in the promoters of Tnf-α, Il-6, and Nos2 and enhanced the mRNA up-regulation of these genes. Accordingly, S-adenosylmethionine administration increased inflammatory infiltrate and edema in pancreas with acute pancreatitis. In conclusion, tyrosine-nitration of cystathionine β-synthase blockades the trans-sulfuration pathway in acute pancreatitis promoting homocysteine accumulation upon S-adenosylmethionine treatment.

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Acute pancreatitis induces nitration of cystathionine β-synthase (CBS).

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CBS nitration blockades the trans-sulfuration pathway in acute pancreatitis.

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SAM treatment enhances CBS nitration leading to homocysteine accumulation in pancreatitis.

Superoxide dismutase mimetic nanoceria restrains cerulein induced acute pancreatitis

Aim: The present study was carried out to assess the effect of nanoceria (NC) on pancreatic inflammation caused by cerulein. Methods: NC was characterized and in vitro studies were carried out in murine macrophages. The in vivo effects were tested on cerulein-induced pancreatitis. Results: In vitro treatment with NC remarkably protected macrophages from lipopolysaccharide-induced inflammation and oxidative stress as evident from the results of 2',7'-dichlorofluorescin diacetate, JC-1 and MitoSox staining. In vivo treatment with NC showed potent superoxide dismutase and catalase mimetic activity, antipancreatitis activity and improved histology. Furthermore, it reduced the expression of p65-NF-κB and acetylation of histone H3 at lysine K14, K56 and K79 residues. Conclusion: We for the first time, demonstrate that NC may be a promising candidate for the therapy of pancreatitis.

Visnagin attenuates acute pancreatitis via Nrf2/NFκB pathway and abrogates associated multiple organ dysfunction

Acute pancreatitis (AP) is an exocrine dysfunction of the pancreas where oxidative stress and inflammatory cytokines play a key role in induction and progression of the disease. Studies have demonstrated that antioxidant phytochemicals have been effective in improving pancreatitis condition, but there are no clinically approved drugs till date. Our study aims to assess the preventive activity of visnagin, a novel phytochemical isolated from Ammi visnaga against cerulein induced AP. Male Swiss albino mice were divided into six groups (n = 6, each group) comprising of normal control, cerulein control, seven day pre-treatment with visnagin at three dose levels; visnagin low dose (10 mg/kg), visnagin mid dose (30 mg/kg), visnagin high dose (60 mg/kg) and visnagin control (60 mg/kg). AP was induced by six injections of cerulein (50 μg/kg, i.p.) on the 7^th day and the animals were sacrificed after 6 h of last cerulein dose. Various markers of pancreatic function, oxidative stress and inflammation were assessed. Visnagin was found to be effective in reducing plasma amylase and lipase levels, reduced cerulein induced oxidative stress. Visnagin dose dependently decreased the expression of IL-1β, IL-6, TNF-α and IL-17. It attenuated the levels of nuclear p65-NFκB. Visnagin improved the antioxidant defence by improving Nrf2 expression and halted pancreatic inflammation by suppressing NFκB and nitrotyrosine expression in the acinar cells. Further, it attenuated the expression of markers of multiple organ dysfunction syndrome and reduced inflammatory cytokines in lungs and intestine. Cumulatively, these findings indicate that visnagin has substantial potential to prevent cerulein induced AP.

Adhesion molecules and pancreatitis

Acute and chronic pancreatitises are gastrointestinal inflammatory diseases, the incidence of which is increasing worldwide. Most (~ 80%) acute pancreatitis (AP) patients have mild disease, and about 20% have severe disease, which causes multiple organ failure and has a high mortality rate. Chronic pancreatitis (CP) is characterized by chronic inflammation and destruction of normal pancreatic parenchyma, which leads to loss of exocrine and endocrine tissues. Patients with CP also have a higher incidence of pancreatic ductal adenocarcinoma. Although a number of factors are associated with the development and progression of AP and CP, the underlying mechanism is unclear. Adhesion molecules play important roles in cell migration, proliferation, and signal transduction, as well as in development and tissue repair. Loosening of cell-cell adhesion between pancreatic acinar cells and/or endothelial cells increases solute permeability, resulting in interstitial edema, which promotes inflammatory cell migration and disrupts tissue structure. Oxidative stress, which is one of the important pathogenesis of pancreatitis, leads to upregulation of adhesion molecules. Soluble adhesion molecules are reportedly involved in AP. In this review, we focus on the roles of tight junctions (occludin, tricellulin, claudin, junctional adhesion molecule, and zonula occludin), adherens junctions (E-cadherin and p120-, α-, and β-catenin), and other adhesion molecules (selectin and intercellular adhesion molecules) in the progression of AP and CP. Maintaining the normal function of adhesion molecules and preventing their abnormal activation maintain the structure of the pancreas and prevent the development of pancreatitis.

New Insight into the Role of Nitric Oxide Pathways in Pancreas

Nitric oxide (NO) is generated by a family of enzymes termed NO synthases (NOS) that convert L-arginine to NO and citrulline. The role of NO as an important biological mediator and recognition of the pathophysiological significance of superoxides/NO interaction has led to an intensive research and development of therapies based on the interception of the NO signaling cascade in the pancreatitis course. However, the presence and localization of the NO-generating enzymes in various organs including pancreas are subject to controversy. We assumed that this controversy might reflect rather the diversity of experimental approaches and an insufficient sensitivity of the methods used. Applying tyramide signal amplification (TSA) immunohistochemical technology, we were able detect all three NOS isoforms both in exocrine and endocrine compartments and in the vasculature in the normal pancreas and in pancreatitis. This also allowed us to demonstrate that oxidative stress runs ahead of NOS up-regulation, which implies that the NO enhancement in the course of pancreatitis is likely to be an adaptive mechanism aimed at maintaining the homeostatic cellular level of the bioactive NO. The aims of this minireview are to describe normal intrapancreatic NO pathways and the role of NO in the pancreatitis course.

Withaferin A, a novel compound of Indian ginseng (Withania somnifera), ameliorates Cerulein-induced acute pancreatitis: Possible role of oxidative stress and inflammation

Acute pancreatitis is an inflammatory disorder of the pancreas that may precipitate due to various reasons such as chronic alcoholism, gall stone obstruction, and life style. Current treatment options offer limited efficacy, as they provide only symptomatic relief. This study is an attempt to study the effects of Withaferin A (WFA) against Cerulein-induced acute pancreatitis in mice. Animals were pretreated with WFA via intraperitoneal route, for 7 days. Plasma amylase and lipase, tissue malondialdehyde (MDA), and glutathione were evaluated for all groups. Western blot analysis; haematoxylin and eosin staining of the liver, lung, and pancreas; immunohistochemistry for nitrotyrosine; and myeloperoxidase activity were performed. Haematoxylin and eosin stained sections significantly revealed the altered architecture and thereby damage in the pancreas, lungs, and liver that has been low in treatment groups. Increased myeloperoxidase and nitrotyrosine have also been reduced upon treatment with WFA. Increased levels of MDA, NO, and expression of myeloperoxidase and nitrotyrosine in the parameters estimated add evidence to the role of oxidative stress and inflammation in acute pancreatitis. WFA evidently altered these conditions upon pretreatment. Our study shows that this novel steroidal compound has potent anti-inflammatory property. Natural compounds can therefore be good remedies against many diseases if incorporated in routine diet as dietary supplement.

Phytoceuticals in Acute Pancreatitis: Targeting the Balance between Apoptosis and Necrosis

Despite recent advances in understanding the complex pathogenesis of pancreatitis, the management of the disease remains suboptimal. The use of phytoceuticals (plant-derived pleiotropic multitarget molecules) represents a new research trend in pancreatology. The purpose of this review is to discuss the phytoceuticals with pancreatoprotective potential in acute pancreatitis and whose efficacy is based, at least in part, on their capacity to modulate the acinar cell death. The phytochemicals selected, belonging to such diverse classes as polyphenols, flavonoids, lignans, anthraquinones, sesquiterpene lactones, nitriles, and alkaloids, target the balance between apoptosis and necrosis. Activation of apoptosis via various mechanisms (e.g., inhibition of X-linked inhibitor of apoptosis proteins by embelin, upregulation of FasL gene expression by resveratrol) and/or inhibition of necrosis seem to represent the essential key for decreasing the severity of the disease. Apart from targeting the apoptosis/necrosis balance, the phytochemicals displayed other specific protective activities: inhibition of inflammasome (e.g., rutin), suppression of neutrophil infiltration (e.g., ligustrazine, resveratrol), and antioxidant activity. Even though many of the selected phytoceuticals represent a promising therapeutic alternative, there is a shortage of human evidence, and further studies are required to provide solid basis to justify their use in the treatment of pancreatitis.

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.

Berberine inhibits inflammatory mediators and attenuates acute pancreatitis through deactivation of JNK signaling pathways

Acute pancreatitis (AP) is a life-threatening disease. Berberine (BBR), a well-known plant alkaloid, is reported to have anti-inflammatory activity in many diseases. However, the effects of BBR on AP have not been clearly elucidated. Therefore, the present study aimed to investigate the effects of BBR on cerulein-induced AP in mice. AP was induced by either cerulein or l-arginine. In the BBR treated group, BBR was administered intraperitoneally 1h before the first cerulein or l-arginine injection. Blood samples were obtained to determine serum amylase and lipase activities and nitric oxide production. The pancreas and lung were rapidly removed for examination of histologic changes, myeloperoxidase (MPO) activity, and real-time reverse transcription-polymerase chain reaction. Furthermore, the regulating mechanisms of BBR were evaluated. Treatment of mice with BBR reduced pancreatic injury and activities of amylase, lipase, and pancreatitis-associated lung injury, as well as inhibited several inflammatory parameters such as the expression of pro-inflammatory cytokines and inducible nitric oxide synthesis (iNOS). Furthermore, BBR administration significantly inhibited c-Jun N-terminal kinase (JNK) activation in the cerulein-induced AP. Deactivation of JNK resulted in amelioration of pancreatitis and the inhibition of inflammatory mediators. These results suggest that BBR exerts anti-inflammatory effects on AP via JNK deactivation on mild and severe acute pancreatitis model, and could be a beneficial target in the management of AP.

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.

Inhibition of glycogen synthase kinase-3β attenuates acute kidney injury in sodium taurocholate‑induced severe acute pancreatitis in rats

The aim of the present study was to investigate the efficacy of 4‑benzyl‑2‑methyl‑1,2,4‑thiadiazolidine‑3,5‑dione (TDZD‑8), the selective inhibitor of glycogen synthase kinase‑3β (GSK‑3β), on the development of acute kidney injury in an experimental model of sodium taurocholate‑induced severe acute pancreatitis (SAP) in rats. The serum amylase, lipase, interleukin‑1β and interleukin‑6 levels, and the pancreatic pathological score were examined to determine the magnitude of pancreatitis injury. The serum creatinine and blood urea nitrogen levels, myeloperoxidase (MPO) activity and renal histological grading were measured to assess the magnitude of SAP‑induced acute kidney injury. The activation of nuclear factor‑κB (NF‑κB) was examined using an immunohistochemistry assay. The expression of GSK‑3β, phospho‑GSK‑3β (Ser9), tumour necrosis factor‑α (TNF‑α), intercellular adhesion molecule‑1 (ICAM‑1) and inducible nitric oxide synthase (iNOS) protein in the kidney was characterised using western blot analysis. TDZD‑8 attenuated (i) serum amylase, lipase and renal dysfunction; (ii) the serum concentrations of proinflammatory cytokines; (iii) pancreatic and renal pathological injury; (iv) renal MPO activity and (v) NF‑κB activation and TNF‑α, ICAM‑1 and iNOS protein expression in the kidney. The results obtained in the present study suggest that the inhibition of GSK‑3β attenuates renal disorders associated with SAP through the inhibition of NF‑κB activation and the downregulation of the expression of proinflammatory cytokines, TNF‑α, ICAM‑1 and iNOS in rats. Blocking GSK‑3β protein kinase activity may be a novel approach to the treatment of this inflammatory condition.

The effects of resveratrol on tissue injury, oxidative damage, and pro-inflammatory cytokines in an experimental model of acute pancreatitis

Acute pancreatitis (AP) is an acute inflammatory condition that results from the digestion of pancreatic tissue by its own enzymes released from the acinar cells. The objective of this study was to investigate the effects of resveratrol on oxidative damage, pro-inflammatory cytokines, and tissue injury involved with AP induced in a rat model using sodium taurocholate (n = 60). There were three treatment groups with 20 rats per group. Groups I and II received 3% sodium taurocholate solution, while group III underwent the same surgical procedure yet did not receive sodium taurocholate. In addition, group II received 30 mg/kg resveratrol solution. Rats were sacrificed at 2, 6, 12, and 24 h time points following the induction of AP. Blood and pancreatic tissue samples were collected and subjected to biochemical assays, Western blot assays, and histopathologic evaluations. Resveratrol did not reduce trypsin levels and prevent tissue damage. Resveratrol prevented IκB degradation (except for 6 h) and decreased nuclear factor-κB (NF-κB), activator protein-1 (AP-1) (except for 24 h), and levels of TNF-α, IL-6 (except for 24 h), and iNOS in the pancreatic tissue at all time points (P < 0.05). Serum nitric oxide (NO) levels were reduced as well (P < 0.05). Thus, we concluded that resveratrol did not reduce trypsin levels and did not prevent tissue injury despite the reduction in oxidative damage and pro-inflammatory cytokine levels detected in this model of AP.

L-arginine-NO-cGMP signalling pathway in pancreatitis

The role of nitric oxide (NO) in the human pancreas and in pancreatitis still remains controversial. Furthermore, conflicting conclusions have been reached by different laboratories about the localization of the NO-generating enzyme (NO synthase, NOS) in the pancreas. Here, we investigated the co-expression of NOS with enzymes involved in regulation of NO signalling in the normal human pancreas and in pancreatitis. We found that the whole NO signalling machinery was up-regulated in pancreatitis, especially within the exocrine compartment. Furthermore, the exocrine parenchymal cells revealed higher levels of oxidative stress markers, nitrotyrosine and 8-hydroxyguanosine, in pancreatitis, which reflects the exceptional susceptibility of the exocrine parenchyma to oxidative stress. This study provides a direct link between oxidative stress and the enzymatic control of the NO bioavailability at the cellular level and endows with further insight into fundamental mechanisms underlying pancreatic disorders associated with disruptions in the L-arginine-NO-cGMP signalling enzyme cascade.

Multiparametric and semiquantitative scoring systems for the evaluation of mouse model histopathology--a systematic review

BACKGROUND

Histopathology has initially been and is still used to diagnose infectious, degenerative or neoplastic diseases in humans or animals. In addition to qualitative diagnoses semiquantitative scoring of a lesion`s magnitude on an ordinal scale is a commonly demanded task for histopathologists. Multiparametric, semiquantitative scoring systems for mouse models histopathology are a common approach to handle these questions and to include histopathologic information in biomedical research.

RESULTS

Inclusion criteria for scoring systems were a first description of a multiparametric, semiquantiative scoring systems which comprehensibly describe an approach to evaluate morphologic lesion. A comprehensive literature search using these criteria identified 153 originally designed semiquantitative scoring systems for the analysis of morphologic changes in mouse models covering almost all organs systems and a wide variety of disease models. Of these, colitis, experimental autoimmune encephalitis, lupus nephritis and collagen induced osteoarthritis colitis were the disease models with the largest number of different scoring systems. Closer analysis of the identified scoring systems revealed a lack of a rationale for the selection of the scoring parameters or a correlation between scoring parameter value and the magnitude of the clinical symptoms in most studies.

CONCLUSION

Although a decision for a particular scoring system is clearly dependent on the respective scientific question this review gives an overview on currently available systems and may therefore allow for a better choice for the respective project.

Effects of mitogen-activated protein kinase signaling pathway inhibition on the development of cerulein-induced acute pancreatitis in mice

OBJECTIVES

Extracellular signal-regulated kinase (ERK) influences a number of pathways in all cells. The ERK cascade has long been known to be central to the activation of cellular processes such as proliferation, differentiation, and oncogenic transformation. The mitogen-activated protein (MAP) serine/threonine family of protein kinases, of which ERK is a member, is evolutionarily conserved and is activated by a mechanism that includes protein kinase cascades. The aim of this study was to investigate the effects of PD98059 [2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one], a highly selective inhibitor of MAP/ERK kinase 1 (MEK1) activation, on the development of acute pancreatitis.

METHODS

Pancreatitis was induced by intraperitoneal injection of cerulein (hourly × 5, 50 μg/kg) and PD98059 (10 mg/kg, 10% dimethylsulfoxide, intraperitoneally) was administrated 1 and 3 hours after cerulein administration.

RESULTS

Cerulein injection resulted in acute necrotizing pancreatitis. On the contrary, pancreatitis histological features, amylase, lipase, pancreas edema, and immunohistochemical staining for leukocyte adhesion molecules, transforming growth factor β, and apoptosis-related proteins were found reduced in PD98059-treated mice.

CONCLUSIONS

We propose that this study could help to clarify the role of MAPK in the regulation of the inflammatory process as acute pancreatitis.

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.

The role of nitric oxide in the physiology and pathophysiology of the exocrine pancreas

SIGNIFICANCE

Nitric oxide (NO), a ubiquitous gaseous signaling molecule, contributes to both pancreatic physiology and pathophysiology.

RECENT ADVANCES

The present review provides a general overview of NO synthesis, signaling, and function. Further, it specifically discusses NO metabolism and its effects in the exocrine pancreas and focuses on the role of NO in the pathogenesis of acute pancreatitis and pancreatic ischemia/reperfusion injury.

CRITICAL ISSUES

Unfortunately, the role of NO in pancreatic physiology and pathophysiology remains controversial in numerous areas. Many questions regarding the messenger molecule still remain unanswered.

FUTURE DIRECTIONS

Probably the least is known about the downstream targets of NO, which need to be identified, especially at the molecular level.

Pomalidomide suppresses cerulein-induced acute pancreatitis in mice

BACKGROUND

An overproduction of proinflammatory mediators in severe acute pancreatitis contributes to the systemic inflammatory response, which may lead to multiorgan damage and even death. Thus, inflammatory cytokines, e.g., tumor necrosis factor (TNF)-α and interleukin (IL)-1β, may be novel targets for the treatment of acute pancreatitis. The aim of this study was to investigate the therapeutic effects of pomalidomide (or CC-4047), a thalidomide analog and immunomodulatory agent, in acute pancreatitis.

METHODS

Acute pancreatitis was induced in C57BL/6 mice by intraperitoneal administration of cerulein (100 μg/kg/h × 8). Pomalidomide was administered (0.5 mg/kg orally) 1 h before the first or 1 h after the last cerulein administration. The severity of the acute pancreatitis was evaluated biochemically and morphologically.

RESULTS

Pretreatment with pomalidomide significantly reduced the plasma levels of amylase and lipase; the histological injury; and the expression of TNF-α, IL-1β, monocyte chemotactic protein-1 (MCP-1), and inducible nitric oxide synthase (iNOS) in cerulein-induced acute pancreatitis. Post-treatment with pomalidomide also decreased the cerulein-induced elevation of plasma amylase and lipase and decreased the pancreatic damage.

CONCLUSIONS

Treatment with pomalidomide ameliorated the severity of cerulein-induced acute pancreatitis in mice. Our data suggest that pomalidomide may become a new therapeutic agent in future clinical trials for the treatment of acute pancreatitis.

Pathophysiological roles of peroxynitrite in circulatory shock

Peroxynitrite is a reactive oxidant produced from nitric oxide and superoxide, which reacts with proteins, lipids, and DNA, and promotes cytotoxic and proinflammatory responses. Here, we overview the role of peroxynitrite in various forms of circulatory shock. Immunohistochemical and biochemical evidences demonstrate the production of peroxynitrite in various experimental models of endotoxic and hemorrhagic shock both in rodents and in large animals. In addition, biological markers of peroxynitrite have been identified in human tissues after circulatory shock. Peroxynitrite can initiate toxic oxidative reactions in vitro and in vivo. Initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3-phosphate dehydrogenase, inhibition of membrane Na+/K+ ATPase activity, inactivation of membrane sodium channels, and other oxidative protein modifications contribute to the cytotoxic effect of peroxynitrite. In addition, peroxynitrite is a potent trigger of DNA strand breakage, with subsequent activation of the nuclear enzyme poly(ADP-ribose) polymerase, which promotes cellular energetic collapse and cellular necrosis. Additional actions of peroxynitrite that contribute to the pathogenesis of shock include inactivation of catecholamines and catecholamine receptors (leading to vascular failure) and endothelial and epithelial injury (leading to endothelial and epithelial hyperpermeability and barrier dysfunction), as well as myocyte injury (contributing to loss of cardiac contractile function). Neutralization of peroxynitrite with potent peroxynitrite decomposition catalysts provides cytoprotective and beneficial effects in rodent and large-animal models of circulatory shock.

Ameliorative effect of adalimumab on experimentally induced acute pancreatitis in rats

OBJECTIVES

In this study, the effects of adalimumab (ADA), a fully humanized IgG1 monoclonal antibody to tumor necrosis factor α, on experimentally acute pancreatitis (AP) were examined.

METHODS

Healthy Wistar rats (n = 32) were randomly divided into 4 groups: group 1, AP; group 2, AP + ADA; group 3, control (physiologic saline), and group 4, physiologic saline + ADA (n = 8/group). Acute pancreatitis was induced with a retrograde injection of 3% sodium (Na)-taurocholate into the common biliopancreatic duct. Adalimumab was simultaneously administered at 50 mg/kg intraperitoneally for groups 2 and 4. Physiologic saline was administered instead of Na-taurocholate for non-AP groups. After 24 hours, serum amylase, lactate dehydrogenase, pancreatic myeloperoxidase, and malondialdehyde activities, along with pancreatic histopathology, were examined.

RESULTS

Adalimumab treatment significantly decreased serum amylase activity (AP, 2778.25 ± 298.80; AP + ADA, 2143.13 ± 221.69; control, 1541.00 ± 148.39; ADA, 1143.00 ± 256.30 U/L; P < 0.001), lactate dehydrogenase activity (AP, 2978.37 ± 364.65; AP + ADA, 2582.75 ± 164.23; control 931.25 ± 135.93; ADA, 582.62 ± 99.37 U/L; P < 0.001), myeloperoxidase activity (AP, 1.44 ± 0.20; AP + ADA, 0.86 ± 0.01; control, 0.60 ± 0.17; ADA, 0.41 ± 0.00 U/g of wet tissue; P < 0.001), malondialdehyde activity (AP, 16.94 ± 3.98; AP + ADA, 7.66 ± 2.27; control, 9.07 ± 1.00; ADA, 3.58 ± 0.30 nmol/g; P < 0.01), and total histopathologic scores (AP, 2.75 ± 0.16; AP + ADA, 1.50 ± 0.19; control, 0.00 ± 0.00; ADA, 0.00 ± 0.00; P < 0.001).

CONCLUSIONS

These results support the idea that adalimumab might be beneficial for severity of AP.

Liver X receptor agonist treatment reduced splanchnic ischemia and reperfusion injury

LXR is another member of the superfamily of nuclear hormone receptors that heterodimerizes with RXR and regulates the intracellular levels of cholesterol through gene induction of enzymes and proteins involved in the cholesterol metabolism and transport. LXR ligands inhibit the gene expression of proinflammatory mediators in immunostimulated macrophages; in vivo studies have shown that activation of LXR reduces the inflammatory response in a murine model of contact dermatitis and atherosclerosis. No reports have addressed a role for LXRs in pathophysiology of intestinal ischemia. The aim of this study was to investigate the effects of T0901317, a potent LXR ligand, in a mouse model of SAO shock, which was induced by clamping the superior mesenteric artery and the celiac trunk, resulting in a total occlusion of these arteries for 30 min. After this period of occlusion, the clamps were removed. Mice were killed at 60 min after reperfusion. This study provides the evidence that T0901317, LXR agonist, modulates: the development of SAO shock; the infiltration of the tissue with PMNs; the expression of TNF-alpha and IL-1beta; the nitration of tyrosine residues; NF-kappaB expression; the MAPK phosphorylation (ERK, JNK, and p38); FasL; apoptosis; Bax and Bcl-2 expression; and the degree of tissue injury caused by SAO shock. Our results imply that LXR agonists may be useful in the therapy of inflammation.

Effects of etanercept on sodium taurocholate-induced acute pancreatitis in rats

In this study, we examined the effects of etanercept (ETA) on experimentally induced pancreatitis. Acute pancreatitis was induced with Na taurocholate. ETA was simultaneously administered to treatment groups. Serum amylase and lipase activity, pancreatic histopathology, apoptosis, malondialdehyde (MDA), and myeloperoxidase enzyme activity (MPO) were assessed. Although rats in the groups 1, 2, and 3 were sacrificed 24h later, groups 4, 5, and 6 were sacrificed 5 days later. ETA treatment significantly decreased serum amylase activity (nontreated, 2636.16+/-191.94; treated, 1898.71+/-262.53; control, 506.28+/-17.31 U/L, P<0.001), lipase activity (nontreated, 3049.67+/-972.65; treated, 2538.85+/-660.45; control, 88.57+/-7.54 U/L, P<0.001), histopathologic score (nontreated, 5.43+/-0.43; treated, 2.57+/-0.20; control, 0.71+/-0.18, P<0.001), MDA (nontreated, 105.77+/-13.29; treated, 92.89+/-10.39; control, 41.26+/-2.54 nmol/g, P<0.001), and MPO (nontreated, 0.64+/-1.15; treated, 0.59+/-0.13; control, 0.17+/-0.02 units/g/wet weight, P<0.001) activity in 24-h groups. In 5-day groups, ETA treatment decreased amylase activity (nontreated, 738.67+/-48.60; treated, 497.14+/-47.25; control, 389.00+/-9.17 U/L, P<0.001), lipase activity (nontreated, 101.33+/-39.32; treated, 34.57+/-7.29; control, 23.42+/-2.12 U/L, P<0.001), histopathologic score (nontreated, 5.43+/-0.43; treated, 3.71+/-0.68; control, 0.00+/-0.00, P<0.001), MDA (nontreated, 67.91+/-4.28; treated, 60.91+/-3.57; control, 14.85+/-1.16 nmol/g, P<0.001), and MPO (nontreated, 0.36+/-0.04; treated, 0.27+/-0.02; control, 0.14+/-0.02 units/g/wet weight, P<0.001) activity. Caspase-positive cells numbers around the necrosis significantly decreased by ETA treatment in both 24-h groups (nontreated, 74.28+/-3.26; treated, 67.00+/-1.15; control, 3.85+/-0.63, P<0.001) and 5-day groups (nontreated, 79.85+/-3.01; treated, 47.85+/-5.76; control, 2.22+/-0.63, P<0.001). These results showed that ETA has an ameliorating effect on sodium taurocholate-induced acute necrotic pancreatitis.

Role of oxidative stress in pancreatic inflammation

Reactive oxygen and reactive nitrogen species (ROS/RNS) have been implicated in the pathogenesis of acute and chronic pancreatitis. Clinical and basic science studies have indicated that ROS/RNS formation processes are intimately linked to the development of the inflammatory disorders. The detrimental effects of highly reactive ROS/RNS are mediated by their direct actions on biomolecules (lipids, proteins, and nucleic acids) and activation of proinflammatory signal cascades, which subsequently lead to activation of immune responses. The present article summarizes the possible sources of ROS/RNS formation and the detailed signaling cascades implicated in the pathogenesis of pancreatic inflammation, as observed in acute and chronic pancreatitis. A therapeutic ROS/RNS-scavenging strategy has been advocated for decades; however, clinical studies examining such approaches have been inconsistent in their results. Emerging evidence indicates that pancreatitis-inducing ROS/RNS generation may be attenuated by targeting ROS/RNS-generating enzymes and upstream mediators.

Expression of nitric oxide synthase isoforms and nitric oxide production in acute pancreatitis and associated lung injury

BACKGROUND/AIMS

The role of nitric oxide (NO) has been increasingly implicated in the pathophysiology of acute pancreatitis (AP). Studies have shown increased NO production in AP although not all are agreeable on whether NO is beneficial or detrimental in AP. This study aims to profile NO production and NO synthase (NOS) expression in the pancreas and lungs in the progression of AP in mice to gain insights to the role played by different NOS isoforms.

METHODS

AP was induced in mice by hourly administration of cerulein. NO production was determined by measuring the total nitrite and nitrate (NOx) content while NOS expression was measured by Western blot.

RESULTS

Pancreatic NO production increased sharply and was sustained throughout AP. iNOS expression was greatly increased while eNOS was downregulated at the later stages. In the lungs, there was an unexpected early increase in the constitutive NOS expression; however iNOS was also significantly overexpressed at the later time point along with a significant increase in NO. Acinar cells were found to overproduce NO in response to cerulein hyperstimulation with iNOS again being the major contributor.

CONCLUSION

These data show that NO production and NOS expression are differentially regulated temporally and in magnitude in the pancreas and lungs in response to cerulein hyperstimulation which suggests differing roles for each NOS isoform. and IAP.

The contradictory effects of nitric oxide in caerulein-induced acute pancreatitis in rats

This study was planned to observe the effects of nitric oxide synthesis on the antioxidative defense enzymes and pancreatic tissue histology in caerulein-induced acute pancreatitis. Acute pancreatitis was induced by intraperitoneal injections of 50 microg/kg caerulein, L-arginine used for NO induction and N(omega)-nitro-L-arginine methyl ester (L-NAME) used for NO inhibition. In the caerulein group acinar cell degeneration, interstitial inflammation, oedema and haemorrhage were detected. Pancreatic damage scores were decreased with both NO induction and inhibition (p<0.05). MDA, GSH-Px, CAT, GSH and SOD activities were significantly changed in the caerulein group and indicated increased oxidative stress. Both NO induction and inhibition decreased this oxidative stress. It is concluded that both nitric oxide induction and inhibition ameliorated caerulein-induced acute pancreatitis. The findings indicate that a certain amount of NO production has beneficial effects in experimental acute pancreatitis, but uncontrolled over-production of NO may be detrimental.

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.

Effects of thalidomide in a mouse model of cerulein-induced acute pancreatitis

Current knowledge shows that pathophysiology of acute pancreatitis is characterized by intraacinar enzyme activation and subsequent dysregulation in immune response. Interactions between leukocytes, soluble mediators such as cytokines and vascular endothelium contribute to the systemic progression of the inflammatory response, whose entity may--in the end--determine disease severity and outcome. Recently, it has been shown that TNF-[alpha] may be a novel target for the treatment of acute pancreatitis; but the role of thalidomide, an immunomodulatory agent that inhibits TNF-(alpha) and angiogenesis, has not been investigated so far. The aim of the present study was to assess the effects of thalidomide in a murine model of necrotizing acute pancreatitis. Necrotizing acute pancreatitis was induced in mice by intraperitoneal injection of cerulein (hourly, x5, 50 microg/kg); in another group of animals, thalidomide was administered (200 mg/kg orally) at 1 h after first cerulein injection. After 24 h, biochemical, histological, and immunohistochemical evidences of acute pancreatitis developed in all cerulein-treated mice. On the contrary, pancreatitis histological features, amylase, lipase, TNF-alpha and IL-1beta levels, pancreas edema, and myeloperoxidase activity as well as immunohistochemical staining for inflammatory cytokines, leukocyte adhesion molecules, transforming growth factor [beta], vascular endothelial growth factor, and apoptosis-related proteins were found reduced in thalidomide-treated mice. Therefore, thalidomide treatment attenuates the development of acute pancreatitis caused by cerulein in mice. We propose that this evidence may help to clarify the role of anti-TNF-alpha and immunomodulatory agents in patients with acute pancreatitis.

Effects of glycogen synthase kinase-3beta inhibition on the development of cerulein-induced acute pancreatitis in mice

OBJECTIVE

Glycogen synthase kinase (GSK)-3 is a ubiquitous serine-threonine protein kinase that participates in a multitude of cellular processes and signal transduction pathways. It also plays an important role in the pathophysiology of a number of diseases characterized by an enhanced or unregulated inflammatory response. Here we investigate the effects of GSK-3beta inhibition on the development of experimental acute pancreatitis induced by cerulein in mice.

DESIGN

Prospective, randomized study.

SETTING

University-based research laboratory.

SUBJECTS

One-hundred and sixty anesthetized male CD mice.

INTERVENTIONS

Pancreatitis was induced by intraperitoneal injection of cerulein (hourly x5, 50 microg/kg). In the treatment group, the potent and selective GSK-3beta inhibitor 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8) was administered 1 hr and 6 hrs after the first injection of cerulein (10 mg/kg, intraperitoneally). Sham groups were treated with vehicle (0.1 mL of 0.9% NaCl, intraperitoneally) and TDZD-8. In another set of experiments, mice were monitored for 24 days to determine their mortality rate.

MEASUREMENTS AND MAIN RESULTS

The injection of cerulein resulted in acute necrotizing pancreatitis. TDZD-8 significantly reduced the degree of pancreas injury, amylase, and lipase serum levels (p < .01); nuclear factor-kappaB activation (p < .01); the production of tumor necrosis factor-alpha and interleukin-1beta (p < .01); the expression of adhesion molecules and neutrophil accumulation (p < .01); the formation of oxygen and nitrogen-derived radicals (p < .01); the degree of lipid peroxidation (p < .01); the expression of transforming growth factor-beta and vascular endothelial growth factor (p < .01); and-ultimately-the mortality rate (p < .01).

CONCLUSIONS

Inhibition of GSK-3beta reduces the degree of cerulein-induced acute pancreatitis and the associated mortality rate in mice. Blocking protein kinase activity may be a novel approach to treatment of this inflammatory condition.

Nitric oxide pathways and evidence-based perturbations in acute pancreatitis

Nitric oxide (NO) is a gaseous neurotransmitter, a vasodilator and paracrine regulator. In the pancreas, NO regulates normal pancreatic exocrine secretion, endocrine pancreatic insulin secretion and pancreatic microvascular blood flow. NO has multiple species and is produced de novo by 3 NO synthase enzymes. Endothelial NO synthase reduces the severity of the initial phase of experimental acute pancreatitis (AP). Cigarette smoking and chronic alcohol use disrupt normal NO pathways and are associated with pancreatitis and pancreatic cancer. The aims of this minireview are to describe normal intrapancreatic NO pathways, perturbations during experimental AP and due to epidemiological factors associated with pancreatic pathology, and the clinical implications of NO on AP.

Role of tumor necrosis factor-alpha in acute pancreatitis: from biological basis to clinical evidence

Tumor necrosis factor (TNF)-alpha is a pleiotropic cytokine that exerts host-damaging effects in different autoimmune and inflammatory diseases. It is a key regulator of other proinflammatory cytokines and of leukocyte adhesion molecules, and it is a priming activator of immune cells. In recent years, several research lines-mostly derived from animal models and in vitro studies-suggested that TNF-alpha plays a pivotal role in the pathogenesis of acute pancreatitis. In particular, it contributes to the systemic progression of the inflammatory response and to the end-organ dysfunction often observed in severe disease. Current clinical applications of TNF-alpha in acute pancreatitis include the assessment of blood concentrations to predict disease severity and to identify individuals prone to develop complications such as multiple organ failure and septic shock. However, TNF-alpha is rapidly cleared from the bloodstream, and sensitivity and overall accuracy of its measurement seem strictly time dependent, thereby being of potential prognostic value only in the first days after the onset of the disease. In parallel, TNF-alpha has been evaluated as a novel pharmacologic target for treating pancreatitis. Although promising results have been observed in the laboratory, transition to clinical practice seems problematic, in particular, in the light of divergent results obtained in sepsis trials. Therefore, in future clinical trials pertaining to TNF-alpha neutralization in acute pancreatitis, timing of intervention should be related to changes in TNF-alpha serum levels, and inclusion and exclusion criteria should be accurately selected to better define the population most likely to benefit.

Etanercept attenuates the development of cerulein-induced acute pancreatitis in mice: a comparison with TNF-alpha genetic deletion

TNF-alpha plays a pivotal role in the pathogenesis of acute pancreatitis. Recent studies have shown that TNF-alpha inhibition significantly ameliorates the course of experimental acute pancreatitis, but in this context, the effects of Etanercept, a novel anti-TNF-alpha agent, have not been investigated so far. The aims of the present study are (i) to assess the effects of pharmacological inhibition of TNF-alpha by means of Etanercept on the inflammatory response and apoptosis in a murine model of necrotizing acute pancreatitis and (ii) to compare the results to those observed in TNF-alpha receptor 1 knockout (TNFR1-KO) mice. Necrotizing acute pancreatitis was induced in TNF-alpha wild type for TNFR1 (WT) and TNFR1-KO mice by intraperitoneal injection of cerulein (hourly x5, 50 microg/kg). In another group of WT mice, Etanercept was administered (5 or 10 mg/kg, s.c.) at 1 h after first cerulein injection. Control groups received saline treatment. After 24 h, biochemical, histological, and immunohistochemical evidences of acute pancreatitis developed in all cerulein-treated mice; apoptosis was also present in the pancreas. Contrarily, pancreatitis histological features, amylase and lipase levels, pancreas water content, and myeloperoxidase activity were reduced in a similar degree in Etanercept-treated and TNFR1-KO mice. Likewise, in these two groups, immunohistochemical stainings and terminal deoxynucleotidyltransferase-mediated UTP nick-end labeling assay were found negative. TNF-alpha receptor 1 gene deletion and Etanercept administration ameliorate the course of experimental acute pancreatitis in a similar degree. Future studies on clinical applications of Etanercept in pancreatitis seem promising.

Nitric oxide in the injured spinal cord: synthases cross-talk, oxidative stress and inflammation

Nitric oxide (NO) is a unique informational molecule involved in a variety of physiological processes in the central nervous system (SNS). It has been demonstrated that it can exert both protective and detrimental effects in several diseases states of the CNS, including spinal cord injury (SCI). The effects of NO on the spinal cord depend on several factors such as: concentration of produced NO, activity of different synthase isoforms, cellular source of production and time of release. Basically, it has been shown that low NO concentrations may play a role in physiologic processes, whereas large amounts of NO may be detrimental by increasing oxidative stress. However, this does not explain all the discrepancies evidenced studying the effects of NO in SCI models. The analysis of the different synthase isoforms, of their temporal profile of activation and cellular source has shed light on this topic. Two post-injury time intervals can be defined with reference to the NO production: immediately after injury and several hours-to-days later. The initial immediate peak of NO production after injury is due to the up-regulation of the neuronal NO synthase (nNOS) in resident spinal cord cells. The late peak is due primarily to the activity of inducible NOS (nNOS) produced by inflammatory infiltrating cells. High NO levels produced by up-regulated nNOS and iNOS are neurotoxic; the down-regulation of nNOS corresponds temporally to the expression of iNOS. On the bases of the evidence, therapeutic approaches should be aimed: (1) to reduce the NO-elicited damage by inhibition of specific synthases according to the temporal profile of activation; (2) by maintaining physiologic amount of NO to keep the induction of iNOS.

Splanchnic ischemia and reperfusion injury is reduced by genetic or pharmacological inhibition of TNF-alpha

In the present study, we used TNF-alpha receptor 1 knockout (TNF-alphaR1KO) mice to evaluate a possible role of TNF-alpha on the pathogenesis of ischemia and reperfusion injury of the multivisceral organs. Ischemia and reperfusion injury was induced in mice by clamping the superior mesenteric artery and the celiac artery for 30 min, followed thereafter by reperfusion. Sixty minutes after reperfusion, animals were killed for histological examination and biochemical studies. Injured wild-type (WT) mice developed a significant increase of ileum TNF-alpha levels, myeloperoxidase activity, and marked histological injury and apoptosis. Ischemia and reperfusion injury of the multivisceral organs was also associated with a significant mortality. Reperfused ileum sections from injured WT mice showed positive staining for P-selectin, VCAM, ICAM-1, and E-selectin. The intensity and degree of P-selectin, E-selectin, VCAM, and ICAM-1 were reduced markedly in tissue sections from injured TNF-alphaR1KO mice. Ischemia and reperfusion-injured TNF-alphaR1KO mice also showed a significant reduction of neutrophil infiltration into the intestine, a reduction of apoptosis, an improved histological status of the intestine, and survival. In addition, we investigated the effect of Etanercept, a TNF-alpha soluble receptor construct, on ischemia and reperfusion injury of the multivisceral organs. Etanercept (5 mg/kg administered i.p. 5 min prior to reperfusion) significantly reduced the inflammatory response and the ileum injury. Taken together, our results clearly demonstrate that TNF-alpha plays an important role in the ischemia and reperfusion injury and put forward the hypothesis that modulation of TNF-alpha expression may represent a novel and possible strategy.

Induction of Nitric Oxide Synthase is a Key Determinant of Progression to Pulmonary Injury in Experimental Pancreatitis

BACKGROUND

The immunomodulatory potential of nitric oxide provides prospective strategies to attenuate inappropriate inflammatory reactions. This study tested the hypothesis that inhibition of nitric oxide synthase (NOS) reduces end-organ injury in pancreatitis.

METHODS

Pancreatitis was induced in male Sprague-Dawley rats by intraperitoneal (i.p.) injection of 20% L-arginine (500 mg/100 g of body weight). Animals were randomized into four groups of 45: Pancreatitis without intervention; pre-treatment with i.p. aminoguanidine (AMG) (50 mg/kg), an isoform-specific inhibitor of inducible NOS; post-treatment with AMG (50 mg/kg); and controls. Pancreatic and pulmonary pathology, neutrophil infiltration (myeloperoxidase activity), endothelial permeability (bronchoalveolar lavage, wet:dry weight ratio), NOS expression, and concentrations of pro-inflammatory cytokines (tumor necrosis factor-alpha; interleukin-6) were assessed.

RESULTS

Inhibition of iNOS significantly reduced end-organ injury. Pancreatic and pulmonary injury scores were markedly attenuated in the AMG treatment groups compared with no intervention (p < 0.05). Increased endothelial permeability (2,411.1 +/- 47.9) and neutrophil sequestration (1.99 +/- 0.01) were manifest in the untreated animals compared with AMG pretreatment (1,286.8 +/- 35.1 and 1,548.0 +/- 0.1; p < 0.05). In addition, a significant reduction in inflammatory cytokine concentrations was observed (p < 0.05).

CONCLUSIONS

Inhibition of inducible NOS encourages a more benign immunologic profile, minimizing the deleterious effects of unrestrained neutrophil sequestration subsequent to pancreatitis.

Pathogenic role of endothelial nitric oxide synthase (eNOS/NOS-III) in cerulein-induced rat acute pancreatitis

Nitric oxide (NO) is a potent pancreatic vasodilator, yet the pathogenic role of NO in acute pancreatitis remains controversial. NO is generated from L-arginine by NO synthase (NOS), classified into three isozymes: neuronal (nNOS), inducible (iNOS), and endothelial NOS (eNOS). The purpose of the present study was to investigate the role of NO/NOS isozymes in the pathogenesis of cerulein-induced acute pancreatitis in rats. Acute pancreatitis was induced in male Wistar rats by two subcutaneous injections of cerulein (20 microg/kg). NG-Nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor) or aminoguanidine (a relatively selective iNOS inhibitor) was given orally, while tetrahydrobiopterin (BH4), a critical cofactor for NOS, was administered intraperitoneally 30 min before the first cerulein injection. Cerulein given repeatedly twice produced acute pancreatitis, with concomitant increases in the serum amylase level, pancreas weight, myeloperoxidase activity, lipid peroxidation and microvascular permeability. Prior administration of L-NAME, but not aminoguanidine, significantly prevented these changes, in a dose-dependent manner, and this effect was antagonized by the coadministration of L-arginine, a precursor of NO. The expression of dimetric eNOS in the pancreas was markedly suppressed by cerulein injections, together with a decrease in NO production, but the response was partially but significantly reversed by the prior administration of BH4. The increases in the serum amylase level and pancreas weight, as well as the lipid peroxidation induced by cerulein, were significantly attenuated by the administration of BH4. L-NAME had no effect on pancreatic secretion induced by cerulein. These results suggest that the uncoupled eNOS, probably caused by the decrease in endogenous BH4 availability, plays a deleterious role in the pathogenesis of cerulein-induced acute pancreatitis.

Hypericum perforatum attenuates the development of cerulein-induced acute pancreatitis in mice

A considerable body of recent evidence suggests that oxidative stress and exaggerated production of reactive oxygen species play a major role in several aspects of inflammation and shock. Hypericum perforatum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Because polyphenolic compounds have high antioxidant potential, in this study we evaluated the effect of Hypericum perforatum extract on acute pancreatitis induced by cerulein administration in male CD mice. Intraperitoneal injection of cerulein in mice resulted in a severe, acute pancreatitis, which was characterized by edema, neutrophil infiltration, tissue hemorrhage, and cell necrosis as well as increases in the serum levels of amylase and/or lipase in comparison to sham-treated mice. The infiltration of the pancreatic tissue of these animals with neutrophils (measured as increase in myeloperoxidase activity) was associated with expression of the adhesion molecule ICAM-1. Immunohistochemical examination demonstrated a marked increase in the staining (immunoreactivity) for nitrotyrosine and poly(ADP-ribose) (PAR) in the pancreas of cerulein-treated mice in comparison to sham-treated mice. In contrast, the degree of (a) pancreatic inflammation and tissue injury (histological score), (b) expression of ICAM-1, (c) the staining for nitrotyrosine and PAR, and (d) myeloperoxidase activity was markedly reduced in pancreatic tissue sections obtained from cerulein-treated mice administered Hypericum perforatum extract (30 mg/kg, suspended in 0.2 mL of saline solution, o.s.). Moreover, the treatment with Hypericum perforatum extract significantly reduced the mortality rate at 5 days after cerulein administration. Taken together, our results indicate that Hypericum perforatum extract reduces the development of acute pancreatitis.

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

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

Protective roles of redox-active protein thioredoxin-1 for severe acute pancreatitis

Severe acute pancreatitis is a disease with high mortality, and infiltration of inflammatory cells and reactive oxygen species have a crucial role in the pathophysiology of this disease. Thioredoxin-1 (TRX-1) is an endogenous redox-active multifunctional protein with antioxidant and anti-inflammatory effects. TRX-1 is induced in various inflammatory conditions and shows cytoprotective effects. The aim of the present study was to clarify the protective roles of TRX-1 in the host defense mechanism against severe acute pancreatitis. Experimental acute pancreatitis was induced by intraperitoneal administration of cerulein, a CCK analog, and aggravated by lipopolysaccharide injection in transgenic mice overexpressing human TRX-1 (hTRX-1) and control C57BL/6 mice. Transgenic overexpression of hTRX-1 strikingly attenuated the severity of experimental acute pancreatitis. TRX-1 overexpression suppressed neutrophil infiltration as determined by myeloperoxidase activity, oxidative stress as determined by malondialdehyde concentration, and cytoplasmic degradation of inhibitor of kappaB-alpha, thereby suppressing proinflammatory cytokines, tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6; a neutrophil chemoattractant, keratinocyte-derived chemokine; and inducible nitric oxide synthase in the pancreas. Administration of recombinant hTRX-1 also suppressed neutrophil infiltration, reduced the inflammation of the pancreas and the lung, and improved the mortality rate. The present study suggests that TRX-1 has potent antioxidant and anti-inflammatory actions in experimental acute pancreatitis and might be a new therapeutic strategy to improve the prognosis of severe acute pancreatitis.

Role of interleukin 18 in nitric oxide production and pancreatic damage during acute pancreatitis

The release of the immunomodulator, interleukin 18 (IL-18) into sera early in acute pancreatitis (AP) corresponds to disease severity. IL-18 induces nitric oxide (NO), which is involved in the pathophysiology of pancreatitis. The objective of this study was to clarify the role of IL-18 in pathogenesis and NO production during early AP using recombinant mouse (rm) IL-18 protein and IL-18 gene knockout (KO) mice. After pretreatment with phosphate-buffered saline or rmIL-18, wild-type (WT) or KO mice were injected intraperitoneally with phosphate-buffered saline (sham) or cerulein (AP) hourly for 3 h. Blood, pancreas, spleen, and liver were collected until 24 h after the first dose. Main outcome measures were serum IL-18, amylase and lipase levels, histological evaluation of the pancreas with parenchyma vacuolization of acinar cells, mRNA expression of inducible NO synthase (iNOS) in the pancreas, and spleen, liver, and plasma NO metabolite level. Serum IL-18 was significantly increased immediately after induction of AP in WT mice. Serum amylase, lipase, and the numbers of acinar cells with parenchyma vacuolization were significantly higher in the group AP/KO than in the group AP/WT, but these parameters were improved by dose-dependent pretreatment with rmIL-18 administration in both groups. Pancreatic iNOS gene expression and plasma NO metabolites were significantly increased by 6 h after the initiation of AP, but were significantly lower in the group AP/KO than in the AP/WT mice. Pretreatment with rmIL-18 also significantly increased these levels in both groups. Splenic and hepatic iNOS expression was not changed after the initiation of AP in WT mice, whereas pretreatment with rmIL-18 also increased these levels. Administration of aminoguanidine, a selective iNOS inhibitor, before AP induction abolished the protective effect of pretreatment with rmIL-18 on pancreatic injury. IL-18 appears to protect the pancreas during early induced-induced AP in mice, probably through induction of NO release from an iNOS source. IL-18 may be a target for new AP therapeutics.