Role of platelet activating factor in pathogenesis of acute pancreatitis in rats

Tropolone derivative hinokitiol ameliorates cerulein-induced acute pancreatitis in mice

Hinokitiol is a natural bio-active tropolone derivative with promising antioxidant and anti-inflammatory properties. This study was conducted to evaluate the ameliorative effects of hinokitiol against acute pancreatitis induced by cerulein. Mice were pre-treated with hinokitiol intraperitoneally for 7 days (50 and 100 mg/kg), and on the final day of study, cerulein (6 × 50 μg/kg) was injected every hour for six times. Six hours after the last dose of cerulein, blood was collected from the mice through retro-orbital plexus for biochemical analysis. After blood collection, mice were euthanized and the pancreas was harvested for studying effects on oxidative stress, pro-inflammatory cytokines, immunohistochemistry and histopathology of tissue sections. Hinokitiol treatment significantly reduced edema of the pancreas and reduced the plasma levels of lipase and amylase in mice with cerulein-induced acute pancreatitis. It also attenuated the oxidative and nitrosative stress related damage as evident from the reduced malondialdehyde (MDA) and nitrite levels, which were significantly increased in the mice with acute pancreatitis. Furthermore, hinokitiol administration significantly reduced the pancreatitis-evoked decrease in the activity of catalase, glutathione (GSH) and superoxide dismutase (SOD) in the pancreatic tissue. Pre-treatment with hinokitiol significantly reduced the elevated levels of pro-inflammatory cytokines like interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α) as well as increased the levels of anti-inflammatory cytokine interleukin-10 (IL-10) in the pancreatic tissue of mice with acute pancreatitis. The immunohistochemical expression of nuclear factor kappa light chain enhancer of activated B cells (NF-κB), cyclooxygenase (COX-2) and TNF-α were significantly decreased by hinokitiol in mice with cerulein-induced acute pancreatitis. In conclusion, the results of the present study demonstrate that hinokitiol has significant potential to prevent cerulein-induced acute pancreatitis.

Hypertriglyceridemia Acute Pancreatitis: Animal Experiment Research

In recent years, the number of acute pancreatitis cases caused by hypertriglyceridemia has increased gradually, which has caught the attention of the medical community. However, because the exact mechanism of hypertriglyceridemic acute pancreatitis (HTG-AP) is not clear, treatment and prevention in clinical practice face enormous challenges. Animal models are useful for elucidating the pathogenesis of diseases and developing and testing novel interventions. Therefore, animal experiments have become the key research means for us to understand and treat this disease. We searched almost all HTG-AP animal models by collecting many studies and finally collated common animals such as rats, mice and included some rare animals that are not commonly used, summarizing the methods to model spontaneous pancreatitis and induce pancreatitis. We sorted them on the basis of three aspects, including the selection of different animals, analyzed the characteristics of different animals, different approaches to establish hypertriglyceridemic pancreatitis and their relative advantages and disadvantages, and introduced the applications of these models in studies of pathogenesis and drug therapy. We hope this review can provide relevant comparisons and analyses for researchers who intend to carry out animal experiments and will help researchers to select and establish more suitable animal experimental models according to their own experimental design.

Capsaicin-Sensitive Sensory Nerves Are Necessary for the Protective Effect of Ghrelin in Cerulein-Induced Acute Pancreatitis in Rats

Ghrelin was shown to exhibit protective and therapeutic effect in the gut. Aim of the study was to investigate the role of sensory nerves (SN) in the protective effect of ghrelin in acute pancreatitis (AP). Studies were performed on male Wistar rats or isolated pancreatic acinar cells. After capsaicin deactivation of sensory nerves (CDSN) or treatment with saline, rats were pretreated intraperitoneally with ghrelin or saline. In those rats, AP was induced by cerulein or pancreases were used for isolation of pancreatic acinar cells. Pancreatic acinar cells were incubated in cerulein-free or cerulein containing solution. In rats with intact SN, pretreatment with ghrelin led to a reversal of the cerulein-induced increase in pancreatic weight, plasma activity of lipase and plasma concentration of tumor necrosis factor-α (TNF-α). These effects were associated with an increase in plasma interleukin-4 concentration and reduction in histological signs of pancreatic damage. CDSN tended to increase the severity of AP and abolished the protective effect of ghrelin. Exposure of pancreatic acinar cells to cerulein led to increase in cellular expression of mRNA for TNF-α and cellular synthesis of this cytokine. Pretreatment with ghrelin reduced this alteration, but this effect was only observed in acinar cells obtained from rats with intact SN. Moreover, CDSN inhibited the cerulein- and ghrelin-induced increase in gene expression and synthesis of heat shock protein 70 (HSP70) in those cells. Ghrelin exhibits the protective effect in cerulein-induced AP on the organ and pancreatic acinar cell level. Sensory nerves ablation abolishes this effect.

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.

A review of animal models of nonneoplastic pancreatic diseases

The nonneoplastic diseases of the human pancreas generally comprise the inflammatory and degenerative conditions that include acute and chronic pancreatitis, with cystic fibrosis being arguably one of the most important diseases that induce the condition. Both acute and chronic conditions vary in severity, but both can be life threatening; and because of this fact, the study of their progression, and their responsiveness to therapy, is largely conducted by indirect means using serum markers of damage and repair such as amylase and lipase activities that normally occur at very low levels in the circulation but can be significantly increased during inflammatory episodes. Progress in the understanding the pathogenesis of both conditions has therefore been largely due to time course studies in animal models of pancreatitis, and it is in this context that animal model development has been so significant. In general terms, the animal models can be divided into the invasive, surgical procedures, and those induced by the administration of chemical secretagogues that induce hypersecretion of the pancreatic enzymes. The former include ligation and/or cannulation of the biliopancreatic ducts with infusion of solutions of various kinds, or the formation of closed duodenal loops. Secretagogue administration includes administration of caerulein or l-arginine in various protocols. An additional model involves administration of dibutyltin dichloride, which induces a partial blockage of the pancreatic ducts to induce pancreatic disease through enzymic reflux into the gland. The models have been invaluable in generating testable hypotheses for the human diseases. These hypotheses for the production of cellular damage as the initiating events in the disease include (1) intracellular chemical activation, (2) pancreatic secretion reflux, (3) intracellular production of reactive oxygen species, and (4) intracellular production of free radicals.

Platelet-activating factor (PAF)-antagonists of natural origin

Presently herbal medicines are being used by about 80% of the world population for primary health care as they stood the test of time for their safety, efficacy, cultural acceptability and lesser side effects. The discovery of platelet activating factor antagonists (PAF antagonists) during these decades are going on with different framework, but the researchers led their efficiency in studying in vitro test models. Since it is assumed that PAF play a central role in etiology of many diseases in humans such as asthma, neuronal damage, migraine, cardiac diseases, inflammatory, headache etc. Present days instinctively occurring PAF antagonist exists as a specific grade of therapeutic agents for the humans against these and different diseases either laid hold of immunological or non-immunological types. Ginkgolide, cedrol and many other natural PAF antagonists such as andrographolide, α-bulnesene, cinchonine, piperine, kadsurenone, different Piper species' natural products and marine origin plants extracts or even crude drugs having PAF antagonist properties are being used currently against different inflammatory pathologies. This review is an attempt to summarize the data on PAF and action of natural PAF antagonists on it, which were evaluated by in vivo and in vitro assays.

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

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

Evaluation of recombinant platelet-activating factor acetylhydrolase for reducing the incidence and severity of post-ERCP acute pancreatitis

BACKGROUND

Pancreatitis is the most common major complication of diagnostic and therapeutic ERCP. Platelet-activating factor (PAF) has been implicated in the pathophysiologic events associated with acute pancreatitis. Animal and human studies suggested that recombinant PAF acetylhydrolase (rPAF-AH) might ameliorate the severity of acute pancreatitis.

OBJECTIVE

Our purpose was to determine whether prophylactic rPAF-AH administration reduces the frequency or severity of post-ERCP pancreatitis in high-risk patients.

DESIGN

Randomized, multicenter, double-blind, placebo-controlled study.

INTERVENTIONS

Patients received rPAF-AH at a dose of either 1 or 5 mg/kg or placebo. Patients were administered a single intravenous infusion over 10 minutes of study drug or placebo <1 hour before ERCP.

MAIN OUTCOME MEASUREMENTS

Standardized criteria were used to diagnose and grade the severity of post-ERCP pancreatitis. Adverse events were prospectively recorded.

RESULTS

A total of 600 patients were enrolled. There were no statistically significant differences among the treatment groups with respect to patient demographics, ERCP indications, and patient and procedure risk factors for post-ERCP pancreatitis with the following exceptions: the rPAF-AH 5 mg/kg group had significantly fewer patients younger than 40 years old and scheduled to undergo a therapeutic ERCP involving the pancreatic sphincter or duct. Post-ERCP pancreatitis occurred in 17.5%, 15.9%, and 19.6% of patients receiving rPAF-AH (1 mg/kg), rPAF-AH (5 mg/kg), and placebo, respectively (P = .59 for rPAF-AH 1 mg/kg vs placebo and P = .337 for rPAF-AH 5 mg/kg vs placebo). There was no statistically significant difference between the groups with regard to the severity of pancreatitis, frequency of amylase/lipase elevation more than 3 times normal, or abdominal pain.

CONCLUSIONS

There was no apparent benefit of rPAF-AH treatment compared with placebo in reducing the incidence of post-ERCP pancreatitis in subjects at increased risk.

Pathophysiological role of platelets and platelet system in acute pancreatitis

The most successful approach for restoring normal long-term glucose homeostasis in type I diabetes mellitus is whole-organ pancreas transplantation. Graft pancreatitis is observed in up to 20% of patients and may lead to loss of the transplanted organ. Several pathophysiological events have been implicated in this form of pancreatitis. The most important cause of early graft pancreatitis is ischemia/reperfusion (I/R)-related disturbance of microvascular perfusion with subsequent hypoxic tissue damage. Recently, considerable evidence accumulated that, among a variety of other pathophysiological events, the activation of platelets can contribute to I/R injury in the course of acute pancreatitis experimentally and clinically. This review summarizes the events affecting platelet function and, therefore, pancreatic microcirculation leading to acute pancreatitis. Therapeutic approaches and own results are presented.

Galanin in the regulation of pancreatic vascular perfusion

OBJECTIVES

Acute pancreatitis is associated with compromised pancreatic microcirculation. Galanin is a vasoactive neuropeptide, but its role in the regulation of pancreatic vascular perfusion (PVP) is unclear.

METHODS

Localization of galanin immunoreactivity was investigated by immunohistochemistry, and the effects of bolus doses of galanin or the antagonist galantide on blood pressure (BP) and PVP (by laser Doppler fluxmetry) were determined in anesthetized possums.

RESULTS

Galanin immunoreactivity was abundant in the possum pancreas particularly around blood vessels. Galanin (0.001-10 nmol) produced a dose-dependent increase in BP (to 177% of baseline) and a complex PVP response consisting of a transient increase, then a fall below baseline with recovery to above baseline. Galantide (0.003-30 nmol) caused a dose-dependent biphasic response in BP, with a reduction, recovery, then a further fall, followed by recovery, whereas PVP increased (178%) then fell (to 56%) of baseline. Similar effects were produced by continuous intravenous infusion of galanin (1 and 10 nmol) or galantide (3 and 30 nmol). The second-phase response of these agents is probably a passive response of the pancreatic vasculature to systemic cardiovascular effects.

CONCLUSIONS

These data suggest that galanin acutely reduces PVP, whereas galantide increases it, implying galanin may be important in the regulation of PVP.

From acute pancreatitis to end-organ injury: mechanisms of acute lung injury

BACKGROUND

Multi-organ dysfunction, and in particular lung injury, is often responsible for the unfavorable outcome of patients with severe acute pancreatitis. Understanding of the mechanisms by which local inflammation in the pancreas leads to end-organ injury is crucial for the development of new therapeutic strategies.

METHODS

A MEDLINE search was performed with the terms "acute pancreatitis," "lung injury," "inflammatory response," "SIRS," and "multi-organ dysfunction." Pertinent articles were selected for analysis.

RESULTS

Modulation of the inflammatory response using a combination of immunomodulatory agents may decrease the incidence of severe pancreatitis-related acute lung injury and acute respiratory distress syndrome.

CONCLUSION

Clinical trials are of utmost importance to establish the validity of such strategies.

Evidence-based treatment of acute pancreatitis: a look at established paradigms

BACKGROUND

The management of acute pancreatitis (AP) is still based on speculative and unproven paradigms in many centers. Therefore, we performed an evidence-based analysis to assess the best available treatment.

METHODS

A comprehensive Medline and Cochrane Library search was performed evaluating the indication and timing of interventional and surgical approaches, and the value of aprotinin, lexipafant, gabexate mesylate, and octreotide treatment. Each study was ranked according to the evidence-based methodology of Sackett; whenever feasible, we performed new meta-analyses using the random-effects model. Recommendations were based on the available level of evidence (A=large randomized; B=small randomized; C=prospective trial).

RESULTS

None of the evaluated medical treatments is recommended (level A). Patients with AP should receive early enteral nutrition (level B). While mild biliary AP is best treated by primary cholecystectomy (level B), patients with severe biliary AP require emergency endoscopic papillotomy followed by interval cholecystectomy (level A). Patients with necrotizing AP should receive imipenem or meropenem prophylaxis to decrease the risk of infected necrosis and mortality (level A). Sterile necrosis per se is not an indication for surgery (level C), and not all patients with infected necrosis require immediate surgery (level B). In general, early necrosectomy should be avoided (level B), and single necrosectomy with postoperative lavage should be preferred over "open-packing" because of fewer complications with comparable mortality rates (level C).

CONCLUSIONS

While providing new insights into key aspects of AP management, this evidence-based analysis highlights the need for further clinical trials, particularly regarding the indications for antibiotic prophylaxis and surgery.

Review of experimental animal models of acute pancreatitis

The underlying mechanisms involved in the pathogenesis of acute pancreatitis are ill understood. The mortality rate of this disease has not significantly improved over the past few decades. Current treatment options are limited, and predominantly aimed at supportive therapy. A key feature of severe acute pancreatitis is the presence of extensive tissue necrosis with both local and systemic manifestations of inflammatory response syndromes. A better understanding of the underlying pathophysiology of severe acute pancreatitis may lead to more targeted therapeutic options, potentially leading to improved survival. Animal models of acute pancreatitis are therefore an essential investigative tool for these aims to be achieved. This review discusses the suitability of recent non-invasive models of acute pancreatitis such as hormone-induced, alcohol-induced, immune-mediated, diet-induced, gene knockout and L-arginine; and invasive models including closed duodenal loop, antegrade pancreatic duct perfusion, biliopancreatic duct injection, combination of secretory hyperstimulation with minimal intraductal bile acid exposure, vascular-induced, ischaemia/reperfusion and duct ligation.

Pharmacological prevention and treatment of acute pancreatitis: where are we now?

Acute pancreatitis is a disease of increasing prevalence, unchanged mortality over many decades, and limited treatment strategies. Progress has been made in developing therapies that reduce the rate of endoscopic retrograde cholangiopancreatography (ERCP)-associated pancreatitis and in preventing infected pancreatic necrosis with intravenous carbapenems. Attempts at reducing pancreatic enzyme output or inhibiting the activity of digestive enzyme proteases have not yielded encouraging results - nor have anti-inflammatory strategies for the treatment of acute pancreatitis been found to be effective so far. Future therapeutic options that are presently being developed or under investigation attempt to restore pancreatic secretory function, interfere with inflammatory pathways in a more effective manner, or inhibit digestive enzyme proteases more selectively.

Inflammatory response on the pancreatic acinar cell injury

Acute pancreatitis is an inflammatory disorder, and inflammation not only affects the pathogenesis but also the course of the disease. Acinar cell injury early in acute pancreatitis leads to a local inflammatory reaction; if marked this leads to a systemic inflammatory response syndrome (SIRS). An excessive SIRS leads to distant organ damage and multiple organ dysfunction syndrome (MODS). MODS associated with acute pancreatitis is the primary cause of morbidity and mortality in this condition. Recent studies by us and other investigators have established the critical role played by inflammatory mediators such as TNF-alpha, IL-1beta, IL-6, IL-8, CINC/GRO-alpha, MCP-1, PAF, IL-10, CD40L, C5a, ICAM-1, MIP1-alpha, RANTES, substance P, and hydrogen sulfide in acute pancreatitis and the resultant MODS. This review intends to present an overview of the inflammatory response that takes place following pancreatic acinar cell injury.

Ischemic preconditioning inhibits development of edematous cerulein-induced pancreatitis: Involvement of cyclooxygenases and heat shock protein 70

AIM: To determine whether ischemic preconditioning (IP) affects the development of edematous cerulein-induced pancreatitis and to assess the role of cyclooxygenase-1 (COX-1), COX-2, and heat shock protein 70 (HSP 70) in this process.

METHODS: In male Wistar rats, IP was performed by clamping of celiac artery (twice for 5 min at 5-min intervals). Thirty minutes after IP or sham operation, acute pancreatitis was induced by cerulein. Activity of COX-1 or COX-2 was inhibited by resveratrol or rofecoxib, respectively (10 mg/kg).

RESULTS: IP significantly reduced pancreatic damage in cerulein-induced pancreatitis as demonstrated by the improvement of pancreas histology, reduction in serum lipase and poly-C ribonuclease activity, and serum concentration of pro-inflammatory interleukin (IL)-1β. Also, IP attenuated the pancreatitis-evoked fall in pancreatic blood flow and pancreatic DNA synthesis. Serum level of anti-inflammatory IL-10 was not affected by IP. Cerulein-induced pancreatitis and IP increased the content of HSP 70 in the pancreas. Maximal increase in HSP 70 was observed when IP was combined with cerulein-induced pancreatitis. Inhibition of COXs, especially COX-2, reduced the protective effect of IP in edematous pancreatitis.

CONCLUSION: Our results indicate that IP reduces pancreatic damage in cerulein-induced pancreatitis and this effect, at least in part, depends on the activity of COXs and pancreatic production of HSP 70.

Effects of R-102444 and its active metabolite R-96544, selective 5-HT2A receptor antagonists, on experimental acute and chronic pancreatitis: Additional evidence for possible involvement of 5-HT2A receptors in the development of experimental pancreatitis

The effects of R-102444 ((2R, 4R)-4-lauroyloxy-2-[2-[2-[2-(3-methoxy)phenyl]ethyl]phenoxy]ethyl-1-methylpyrrolidine hydrochloride) and its active metabolite R-96544 ((2R, 4R)-2-[2-[2-[2-(3-methoxy)phenyl]ethyl]phenoxy]ethyl-4-hydroxy-1-methylpyrrolidine hydrochloride), potent and selective 5-hydroxytryptamine 2A (5-HT2A) receptor antagonists, on development of pancreatitis were investigated in experimental models of acute and chronic pancreatitis. Rat acute pancreatitis was induced by caerulein (20 microg/kg) intraperitoneal injection and by pancreatic duct ligation. In both the models, serum amylase and lipase activities were markedly increased. R-102444 dose-dependently reduced these enzyme activities at a dose range of 10 to 100 mg/kg (p.o.) for the caerulein model and 0.3 to 10 mg/kg (p.o.) for the ligation model. In a mouse model of acute pancreatitis induced by a choline-deficient, ethionine (0.5%)-supplemented diet, subcutaneous administration of R-96544 (10-100 mg/kg, bid) reduced serum amylase activity. Histological analysis showed that R-96544 dose-dependently attenuated pancreatic necrosis, inflammation and vacuolization. The effect of R-102444 was further examined in male Wistar Bonn/Kobori rats (4-9 months of age) which spontaneously show pancreatic fibrosis and parenchymal destruction compatible with human chronic pancreatitis. In Wistar Bonn/Kobori rats (from 3 to 9 months of age) fed a diet containing 0.017% and 0.17% of R-102444, pancreatic weight, pancreatic protein and amylase content were higher compared to those in non-treated pancreatitis control rats. Histological analysis showed that R-102444 suppressed parenchymal destruction and replacement with adipose tissue, indicating inhibition of pancreatic atrophy. These results clearly indicate that R-102444 and R-96544 inhibit the progression of acute and chronic pancreatitis and support the contention of possible involvement of 5-HT2A receptors in the progression of experimental pancreatitis.

Pathophysiology of acute pancreatitis

Acute pancreatitis is a common clinical condition. It is a disease of variable severity in which some patients experience mild, self-limited attacks while others manifest a severe, highly morbid, and frequently lethal attack. The exact mechanisms by which diverse etiological factors induce an attack are still unclear. It is generally believed that the earliest events in acute pancreatitis occur within acinar cells. Acinar cell injury early in acute pancreatitis leads to a local inflammatory reaction. If this inflammatory reaction is marked, it leads to a systemic inflammatory response syndrome (SIRS). An excessive SIRS leads to distant organ damage and multiple organ dysfunction syndrome (MODS). MODS associated with acute pancreatitis is the primary cause of morbidity and mortality in this condition. Recent studies have established the role played by inflammatory mediators in the pathogenesis of acute pancreatitis and the resultant MODS. At the same time, recent research has demonstrated the importance of acinar cell death in the form of apoptosis and necrosis as a determinant of pancreatitis severity. In this review, we will discuss about our current understanding of the pathophysiology of acute pancreatitis.

Potential new therapies for the treatment of acute pancreatitis

The treatment of acute pancreatitis has remained virtually unchanged for the past 50 years, in large part due to a poor understanding of the initial intracellular events. Furthermore, there is a lack of knowledge regarding the mediator(s) responsible for the progression of the disease from local pancreatic inflammation to a systemic inflammatory disease, as well as the mediator(s) responsible for distant organ dysfunction and failure. With recent advances in the pathophysiology of pancreatitis, in particular the role of the inflammatory mediators interleukin-1 beta, tumour necrosis factor alpha and platelet-activating factor, the potential for new effective therapies has been realised. At present, a number of inflammatory mediator antagonists are being tested in humans, with the hope that we may soon develop a specific treatment for a disease, which thus far, has none.

Management of the critically ill patient with severe acute pancreatitis

OBJECTIVE

Acute pancreatitis represents a spectrum of disease ranging from a mild, self-limited course requiring only brief hospitalization to a rapidly progressive, fulminant illness resulting in the multiple organ dysfunction syndrome (MODS), with or without accompanying sepsis. The goal of this consensus statement is to provide recommendations regarding the management of the critically ill patient with severe acute pancreatitis (SAP).

DATA SOURCES AND METHODS

An international consensus conference was held in April 2004 to develop recommendations for the management of the critically ill patient with SAP. Evidence-based recommendations were developed by a jury of ten persons representing surgery, internal medicine, and critical care after conferring with experts and reviewing the pertinent literature to address specific questions concerning the management of patients with severe acute pancreatitis.

DATA SYNTHESIS

There were a total of 23 recommendations developed to provide guidance to critical care clinicians caring for the patient with SAP. Topics addressed were as follows. 1) When should the patient admitted with acute pancreatitis be monitored in an ICU or stepdown unit? 2) Should patients with severe acute pancreatitis receive prophylactic antibiotics? 3) What is the optimal mode and timing of nutritional support for the patient with SAP? 4) What are the indications for surgery in acute pancreatitis, what is the optimal timing for intervention, and what are the roles for less invasive approaches including percutaneous drainage and laparoscopy? 5) Under what circumstances should patients with gallstone pancreatitis undergo interventions for clearance of the bile duct? 6) Is there a role for therapy targeting the inflammatory response in the patient with SAP? Some of the recommendations included a recommendation against the routine use of prophylactic systemic antibacterial or antifungal agents in patients with necrotizing pancreatitis. The jury also recommended against pancreatic debridement or drainage for sterile necrosis, limiting debridement or drainage to those with infected pancreatic necrosis and/or abscess confirmed by radiologic evidence of gas or results or fine needle aspirate. Furthermore, the jury recommended that whenever possible, operative necrosectomy and/or drainage be delayed at least 2-3 wk to allow for demarcation of the necrotic pancreas.

CONCLUSIONS

This consensus statement provides 23 different recommendations concerning the management of patients with SAP. These recommendations differ in several ways from previous recommendations because of the release of recent data concerning the management of these patients and also because of the focus on the critically ill patient. There are a number of important questions that could not be answered using an evidence-based approach, and areas in need of further research were identified.

Soluble CD14 receptor expression and monocyte heterogeneity but not the C-260T CD14 genotype are associated with severe acute pancreatitis

OBJECTIVE

Soluble CD14 is derived from a membrane glycoprotein, and it enhances endothelial cytokine responses to lipopolysaccharide. We studied the role of soluble CD14 in the pathogenesis of the systemic inflammatory response associated with acute pancreatitis, to determine whether altered expression was due to a functional C-260T polymorphism in the CD14 promoter gene or altered monocyte heterogeneity.

DESIGN

Prospective case-matched study.

SETTING

Tertiary pancreatic treatment unit in the United Kingdom.

SUBJECTS

Patients with pancreatitis and controls.

INTERVENTIONS

DNA from 117 patients with pancreatitis (34 severe) and 263 controls underwent CD14 genotyping using restriction fragment length polymorphism-polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

Peripheral venous blood samples at 24 and 72 hrs after the onset of abdominal pain were analyzed for sCD14 levels. Isolated peripheral blood mononuclear cells were phenotyped for CD14/CD16 receptor expression using immunofluorescence flow cytometry. Disease severity was assessed using Atlanta criteria, Acute Physiology Scores, and C-reactive protein.Soluble CD14 levels were higher in severe (24-hr median, 66.6 ng/mL; 72-hr median, 72.2 ng/mL) compared with mild attacks (24-hr median, 50.7 ng/mL; 72-hr median, 49.7 ng/mL, p < .001), although the latter was similar to controls (median, 51 ng/mL). Furthermore, soluble CD14 levels correlated with Acute Physiology Scores (p < .001) and C-reactive protein (p = .01).Peripheral blood mononuclear cells CD14++ (p = .008), CD14+/16+ (p = .003), and CD16++ (p = .015) receptor densities were all increased in severe attacks at 24 hrs. Early CD14+/16+ receptor density correlated with sCD14 (p < .001), Acute Physiology Scores (p < .001), and C-reactive protein (p = 0.006). The CD14 genotype prevalence in acute pancreatitis was similar to controls and failed to correlate with any variables studied.

CONCLUSIONS

Increased soluble CD14 expression is associated with the systemic inflammatory response to acute pancreatitis and an expansion of the proinflammatory CD14+/CD16+ monocyte subset. Its targeted disruption may afford some benefit in preventing the development of systemic complications.

Adenosine uptake inhibitors

Adenosine is a purine nucleoside and modulates a variety of physiological functions by interacting with cell-surface adenosine receptors. Under several adverse conditions, including ischemia, trauma, stress, seizures and inflammation, extracellular levels of adenosine are increased due to increased energy demands and ATP metabolism. Increased adenosine could protect against excessive cellular damage and organ dysfunction. Indeed, several protective effects of adenosine have been widely reported (e.g., amelioration of ischemic heart and brain injury, seizures and inflammation). However, the effects of adenosine itself are insufficient because extracellular adenosine is rapidly taken up into adjacent cells and subsequently metabolized. Adenosine uptake inhibitors (nucleoside transport inhibitors) could retard the disappearance of adenosine from the extracellular space by blocking adenosine uptake into cells. Therefore, it is expected that adenosine uptake inhibitors will have protective effects in various diseases, by elevating extracellular adenosine levels. Protective or ameliorating effects of adenosine uptake inhibitors in ischemic cardiac and cerebral injury, organ transplantation, seizures, thrombosis, insomnia, pain, and inflammatory diseases have been reported. Preclinical and clinical results indicate the possibility of therapeutic application of adenosine uptake inhibitors.

Protective effects of rhubarb on experimental severe acute pancreatitis

AIM: To investigate the effects of rhubarb on severe acute pancreatitis (SAP) in rats.

METHODS: Severe acute pancreatitis was induced by two intraperitoneal injections of cerulein (40 μg/kg body weight) plus 5-h restraint water-immersion stress. Rhubarb (75-150 mg/kg) was orally fed before the first cerulein injection. The degree of pancreatic edema, serum amylase level, local pancreatic blood flow (PBF), and histological alterations were investigated. The effects of rhubarb on pancreatic exocrine secretion in this model were evaluated by comparing with those of somatostatin.

RESULTS: In the Cerulein + Stress group, severe edema and diffuse hemorrhage in the pancreas were observed, the pancreatic wet weight (11.60 ± 0.61 g/Kg) and serum amylase (458 490 ± 43 100 U/L) were markedly increased (P < 0.01 vs control). In the rhubarb (150 mg/kg) treated rats, necrosis and polymorphonuclear neutrophil (PMN) infiltration in the pancreas were significantly reduced (P < 0.01), and a marked decrease (50%) in serum amylase levels was also observed (P < 0.01). PBF dropped to 38% (93 ± 5 mL/min per 100 g) of the control in the Cerulein + Stress group and partly recovered in the Cerulein + Stress + Rhubarb 150 mg group (135 ± 12 mL/min per 100 g) (P < 0.01). The pancreatic exocrine function was impaired in the SAP rats. The amylase levels of pancreatic juice were reduced in the rats treated with rhubarb or somatostatin, comparing with that of untreated SAP group. The bicarbonate concentration of pancreatic juice was markedly elevated only in the rhubarb-treated group (P < 0.01).

CONCLUSION: Rhubarb can exert protective effects on SAP, probably by inhibiting the inflammation of pancreas, improving pancreatic microcirculation, and altering exocrine secretion.

Disruption of paracellular sealing is an early event in acute caerulein-pancreatitis

Caerulein-induced pancreatitis is a widely used experimental model for studies on acute pancreatitis, however, the molecular mechanisms underlying pancreatitis in response to caerulein hyperstimulation are incompletely understood. We therefore studied early effects of caerulein on tight junctional integrity. Mice were injected with the cholecystokinin analogue caerulein (50microg/kg BW/h) to induce pancreatitis. In pancreatic tissue occludin, claudin 1, zonula occludens protein 1 (ZO-1) were stained immunohistochemically and F-actin was visualized with phalloidin-TRITC. Stained sections and isolated acini were studied by confocal laser scanning microscopy. Under control conditions occludin, claudin1, ZO-1, and F-actin showed a linear staining pattern delineating the apical membranes of intralobular duct cells and of acinar cells. While in vitro caerulein hyperstimulation induced within 10 minutes disassembly of both occludin and ZO-1, in vivo caerulein hyperstimulation induced disassembly of occludin and claudin1 but not of ZO-1 from the tight junctions. Subsequent progressive disruption of ZO-1 was detected in a time dependent manner. Disruption of the transmembrane tight junction proteins occludin and claudin1 is an early event of caerulein hyperstimulation and may allow evasion of noxious luminal content into the interstitium, which may augment edema formation in acute pancreatitis.

Pancreas: healing response in critical illness

OBJECTIVE

The pathophysiology of acute pancreatitis represents a diverse mix of congenital, hereditary, and acquired problems associated with or causing acute pancreatic inflammation. Acute pancreatitis is characterized by acinar cell injury that may involve regional and systemic inflammatory responses. The systemic manifestations of acute pancreatitis are responsible for the majority of pancreatitis-associated morbidity and are due to the actions of specific inflammatory cytokines. This report summarizes this pancreatic injury, the role of cytokines in the pathogenesis of acute pancreatitis, and the pancreatic healing response that follows.

DESIGN

A comprehensive literature review of experimental pancreatitis as well as reports of cytokine involvement and healing response during clinical pancreatitis was performed.

RESULTS

Histamine release, bradykinin generation, and cytokine release play a significant role during acute pancreatic inflammation. Following an experimental insult, there is rapid expression of tumor necrosis factor-alpha, interleukin-6, interleukin-1, and chemokines by pancreatic acinar cells and/or transmigrated leukocytes. Preventing the action of these mediators has a profound beneficial effect in experimental animals. Pancreatic fibrosis is a central histologic response after pancreatitis. Transient collagen deposition with acinar necrosis occurs in acute pancreatitis; in chronic pancreatitis, permanent and disorganized pancreatic fibrosis and parenchymal cell atrophy occur.

CONCLUSIONS

Inflammatory mediators are responsible for the systemic manifestations of acute pancreatitis and the associated distant organ dysfunction. After the acute injury, regeneration or pancreatic repair is characterized by decreased release of proinflammatory mediators and decreased infiltrating inflammatory cells. Differentiation and proliferation of pancreatic myofibroblasts or "stellate" cells may be responsible for increased extracellular matrix production. The predictable nature in which the inflammation and fibrosis are produced may stimulate novel approaches to disease treatment.

Influence of platelet activating factor on expression of adhesion molecules in experimental pancreatitis

AIM: To determine whether Platelet activating factor (PAF) has a regulation role in the expression of adhesion molecules and accumulation of neutrophils in a murine model of acute pancreatitis.

METHODS: One hundred twenty-eight Kunming mice were divided into four groups. Group 1 received 0.1 mL saline s.c. every hour for three hours (sham). Group 2 received cerulein (50 μg/kg dose s.c.) every hour for three hours. Group 3 received AP and additional challenge of PAF (50 mg/kg in absolute ethanol) (AP/PAF). Group 4 received AP, plus therapeutic treatment with GAB (25 mg dose i.p.) immediately after the first challenge of cerulein (AP/GAB). Animals were sacrificed at 12 h after the first challenge of saline or cerulein. Adhesion molecules of pancreas were semi-quantified by SP methods. Standard assays were performed for serum amylase and myeloperoxidase activity (MPO) of pancreas. Histology of pancreas was scored in a blind manner. Water content of pancreas was also measured at the same time.

RESULTS: Control pancreata showed negligible adhesion molecule expression and neutrophil accumulation. There were evident adhesion molecules expression and neutrophil accumulation in AP and AP/PAF compared with sham (P < 0.05). AP/GAB had a lower level of adhesion molecules, neutrophils, and water content versus AP and AP/PAF (P < 0.05). Histology showed a trend toward improvement in AP/GAB, but did not reach statistical significance.

CONCLUSION: PAF can induce the expression of adhesion molecules that mediate neutrophil accumulation. The PAF antagonist reduces the expression of adhesion molecules and the severity of inflammation when given immediately after the induction of mild AP in mice. These results suggest that PAF antagonism may be useful in the treatment of mild pancreatitis after its clinical onset.

Acute pancreatitis--the current status in management

Acute pancreatitis is a life-threatening inflammatory disorder of the pancreas. Currently, there is no effective pharmacological therapy available for this disorder. The management strategies remain supportive. Given the remarkable morbidity and mortality associated with acute pancreatitis, there is clearly a desperate need for effective novel therapies. This paper presents a review on the epidemiology, aetiology, pathogenesis and management of acute pancreatitis and highlights the need for the development of novel and more specific therapies to battle this disorder.

Pancreatic capillary blood flow during caerulein-induced pancreatitis evaluated by a laser-doppler flowmeter in rats

PURPOSE: The pancreatic capillary blood flow (PCBF) was studied to determine its alterations during caerulein-induced pancreatitis in rats. METHODS: Twenty rats were divided in groups: control and caerulein. A laser-Doppler flowmeter to measure PCBF continuously was used. Blood pressure (BP) and heart rate (HR) were monitored. Serum biochemistry analyses were determined. Histopathological study was performed. RESULTS: The PCBF measured a mean of 109.08 ± 14.54% and 68.24 ± 10.47% in control group and caerulein group, respectively. Caerulein group had a mean decrease of 31.75 ± 16.79%. The serum amylase was 1323.70 ± 239.10U.I-1 and 2184.60 ± 700.46U.I-1 in control and caerulein groups, respectively. There was a significant difference in the PCBF (p<0.05) and serum amylase (p<0.05) when compared to control and caerulein groups. Although micro and microvacuolization were seen in 30% in caerulein group, no significant difference was seen between the groups. CONCLUSION: A decrease in the PCBF may be one of the leading events and it is present before histopathological tissue injury had been established in this model of acute pancreatitis.

Adenosine uptake inhibition ameliorates cerulein-induced acute pancreatitis in mice

INTRODUCTION AND AIMS

Adenosine shows protective effects against cellular damage and dysfunction under several adverse conditions such as inflammation and ischemia. In the current study, we examined the effects of 3-[1-(6,7-diethoxy-2-morpholinoquinazolin-4-yl)piperidin-4-yl]-1,6-dimethyl-2,4(1,3 )-quinazolinedione hydrochloride (KF24345), an adenosine uptake inhibitor, on cerulein-induced acute pancreatitis in mice to investigate whether inhibition of adenosine uptake could ameliorate the severity of acute pancreatitis.

METHODOLOGY

Acute pancreatitis was induced in mice with six intraperitoneal injections of cerulein (50 microg/kg each) at hourly intervals.

RESULTS

The cerulein injection increased activities of serum amylase and lipase and caused pathologic changes such as interstitial edema, polymorphonuclear cell infiltration, and acinar cell necrosis in the pancreas. KF24345 (10 mg/kg p.o.) ameliorated all these changes observed in mice with acute pancreatitis, and the suppressing effect of KF24345 on the elevation in serum amylase activity was abolished by the treatment with 8-(p-sulfophenyl)theophylline, an adenosine receptor antagonist. In addition, 2-(aminocarbonyl)- -(4-amino-2,6-dichlorophenyl)-4-[5,5-bis-(4-fluorophenyl)pentyl]-1-piperazineacetamide (R75231) and dipyridamole, other adenosine uptake inhibitors, also decreased the elevated serum amylase activity.

CONCLUSIONS

These are the first demonstrations that the adenosine uptake inhibitors ameliorate cerulein-induced acute pancreatitis in mice, and these data suggest that adenosine uptake inhibition could ameliorate the severity of acute pancreatitis in vivo.

KF24345, an adenosine uptake inhibitor, ameliorates the severity and mortality of lethal acute pancreatitis via endogenous adenosine in mice

Adenosine protects against cellular damage and dysfunction under several adverse conditions including inflammation and ischemia. In this study, we examined the effects of 3-[1-(6,7-diethoxy-2-morpholinoquinazolin-4-yl)piperidin-4-yl]-1,6-dimethyl-2,4(1H,3H)-quinazolinedione hydrochloride (KF24345), an adenosine uptake inhibitor, on experimental acute pancreatitis induced by choline-deficient and ethionine-supplemented diet in mice. KF24345, administered with the diet onset and every 24 h thereafter, prevented hyperamylasemia, acinar cell injury and serum tumor necrosis factor-alpha elevation and ultimately decreased mortality. Therapeutic treatment with KF24345, which started 32 h after the diet onset, also decreased mortality. The beneficial effect of KF24345 on mortality was abolished by the pretreatment with 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385), a selective adenosine A(2A) receptor antagonist. An intravenous injection of KF24345 at 48 h after the diet onset increased plasma adenosine concentrations in mice with acute pancreatitis. These results suggest that KF24345 shows anti-pancreatitis effects via endogenous adenosine and adenosine A(2A) receptors. The adenosine uptake inhibition could be a new therapeutic approach for acute pancreatitis.

Ultrasonographic splanchnic arterial flow measurement in severe acute pancreatitis

INTRODUCTION

Duplex ultrasonographic technology is now capable of detecting flow signals in the various splanchnic vessels and calculating the concomitant flow velocities using fast-Fourier transformation.

AIM

To use Doppler sonography to investigate how splanchnic hemodynamics vary during the early stage of severe acute pancreatitis.

METHODOLOGY

Six patients with severe acute pancreatitis (age, 59.0 +/- 6.57 years; four men, two women) and seven with mild to moderate acute pancreatitis (age, 60.1 +/- 7.41 years; five men, two women) were examined with Doppler sonography immediately after disease onset. The maximum velocity, minimum velocity, mean velocity, pulsatility index, and resistive index were determined from the Doppler spectra from the proper hepatic artery, celiac artery, and superior mesenteric artery. We also examined 15 healthy subjects (age, 59.3 +/- 4.60 years; 10 men, five women) as controls.

RESULTS

The maximum velocity of the proper hepatic artery in patients with severe acute pancreatitis was significantly higher than that in patients with mild to moderate acute pancreatitis (p = 0.011) and in control subjects (p = 0.0047). Similarly, significant increases in both the minimum velocity and the mean velocity of the proper hepatic artery were observed in patients with severe acute pancreatitis. Neither pulsatility index nor resistive index of the proper hepatic artery showed a significant difference among the three groups. There were no significant differences among the three groups with respect to the flow velocity of the superior mesenteric artery. In contrast, the pulsatility index of the superior mesenteric artery in patients with severe acute pancreatitis was significantly lower than that in patients with mild to moderate acute pancreatitis (p = 0.0058) or in control subjects (p = 0.0024). For patients with acute pancreatitis, a significant inverse correlation was obtained between the maximum velocity of the proper hepatic artery and the pulsatility index of the superior mesenteric artery (r = -0.658, p = 0.0145).

CONCLUSION

The increase in the hepatic arterial flow velocity and the decrease in the superior mesenteric arterial pulsatility index may represent early events of the severe type of acute pancreatitis.

Hepatocyte growth factor attenuates pancreatic damage in caerulein-induced pancreatitis in rats

Hepatocyte growth factor (HGF) overexpression was reported in experimental and clinical acute pancreatitis. These observations prompted us to determine the effect of HGF administration on the development of caerulein-induced pancreatitis in rats. Acute pancreatitis was induced by s.c. infusion of caerulein (10 microg/kg/h) for 5 h. HGF was administrated twice (30 min before caerulein or saline infusion and 3 h later) at the doses: 0.4, 2, 10 or 50 microg/kg s.c. Immediately after cessation of caerulein or saline infusion, the pancreatic blood flow, plasma amylase and lipase activity, plasma cytokines concentration, cell proliferation, and morphological signs of pancreatitis were examined. Caerulein administration induced acute edematous pancreatitis manifested by 41% decrease in DNA synthesis, 53% inhibition of pancreatic blood flow, a significant increase in plasma amylase and lipase activity, plasma interleukin-1beta and interleukin-6 concentration, as well as, the development of the histological signs of pancreatic damage (edema, leukocyte infiltration, and vacuolization). Administration of HGF without induction of pancreatitis increased plasma interleukin-10. Treatment with HGF, during induction of pancreatitis, increased plasma interleukin-10 and attenuated the pancreatic damage, what was manifested by histological improvement of pancreatic integrity, the partial reversion of the drop in DNA synthesis and pancreatic blood flow, and the reduction in pancreatitis evoked increase in plasma amylase, lipase, and interleukin-1beta and interleukin-6 levels. HGF administrated at the dose 2 microg/kg exhibited a similar beneficial effect as administration of HGF at the doses 10 or 50 microg/kg. Treatment with HGF at the dose 0.4 microg/kg was less effective. We conclude that: (1) administration of HGF attenuates pancreatic damage in caerulein-induced pancreatitis; (2) this effect seems to be related to the increase in production of interleukin-10, the reduction in release of interleukin-1beta and interleukin-6, and the improvement of pancreatic blood flow.

Platelet activating factor antagonism reduces the systemic inflammatory response in a murine model of acute pancreatitis

BACKGROUND

The platelet activating factor (PAF) antagonist, Lexipafant, has been used in experimental models and clinical trials to treat severe acute pancreatitis (AP). The purpose of this study was to determine whether Lexipafant reduces the local and systemic components of AP in a murine model of mild, edematous AP.

MATERIALS AND METHODS

Forty-eight female Swiss-Webster mice were divided into four groups. Group 1 received 50 microl of saline ip every hour for 6 h (sham). Group 2 received saline treatment, plus Lexipafant (25 mg/kg dose ip, every 3 h starting 1 h after the first saline injection) (sham/Lex). Group 3 received cerulein (50 microg/kg dose ip, every hour for 6 h) (AP). Group 4 received AP, plus therapeutic treatment with Lexipafant (AP/Lex). Animals were sacrificed 3 h after the last injection. Serum cytokine levels were determined by ELISA. Standard assays were performed for serum amylase activity and lung myeloperoxidase activity (MPO). Histology was scored by two blinded investigators.

RESULTS

Serum cytokines (TNFalpha, IL-1beta), lung MPO, and serum amylase activity were reduced by PAF antagonism. Histology showed a trend toward improvement with Lexipafant, but did not reach statistical significance.

CONCLUSION

The PAF antagonism reduces the severity of systemic inflammation when given after the induction of mild AP in mice. These results suggest that Lexipafant may be useful in the treatment of mild pancreatitis after its clinical onset.

Effect of platelet-activating factor antagonists (BN-52021, WEB-2170, and BB-882) on bacterial translocation in acute pancreatitis

Bacterial translocation is an important source of pancreas infection in acute pancreatitis. The effect of platelet-activating factor (PAF) in the pathogenesis of acute pancreatitis has been proved in various studies. The aim of this study was to determine whether potent PAF antagonists influence bacterial translocation in acute pancreatitis. Acute pancreatitis was induced in 62 Wistar rats by injection of 2.5% sodium taurocholate into the biliopancreatic duct. The rats treated with PAF factor antagonists received intravenous injection of WEB-2170 (10 mg/kg), lexipafant (5 mg/kg), and BN-52021 (5 mg/kg) 30 minutes before induction of acute pancreatitis. Six hours after induction of acute pancreatitis, bacteriologic cultures and histologic scoring of tissues were performed. There was a statistically significant reduction in bacterial translocation to the mesenteric lymph nodes and liver but not to the pancreas of the rats treated with PAF antagonists. No significant increase in the intestinal bacterial population of any group was found. There were no statistical differences between the pancreatic histologic scores of the groups. PAF antagonists reduced bacterial translocation to distant sites other than the pancreas, preventing the bacterial dissemination that occurs in the early phase of acute pancreatitis and may have beneficial effects on the evolution of this disease.

Ascites of rat experimental model of severe acute pancreatitis induces lung injury

The molecular mechanisms that lead from acute pancreatitis (AP) to multiple organ failure remain to be clarified. We previously reported that ascitic fluids from a rat model of severe acute pancreatitis (pancreatitis-associated ascitic fluids, PAAF) transcriptionally activated endothelial cells and leukocytes in vitro. To clarify the role of ascitic fluids on the development of multiple organ failure in AP, we examined the effects of PAAF on the prognosis and immunohistologic findings in cerulein pancreatitis, an experimental model of mild pancreatitis in vivo. Intraperitoneal injection of PAAF decreased the survival rates in a dose-dependent manner. Histologically, destruction of vessels, alveolar septal thickening, interstitial hypertrophy, and infiltration of inflammatory cells were prominent in the lung of PAAF-injected rats. Transcription factor, nuclear factor KB (NF-kappaB) was activated and the mRNA levels of tumor necrosis factor-alpha and interleukin-1beta were increased in the lung of the PAAF-injected rats. The permeability index assessed by Evans blue assay and the lung myeloperoxidase activity levels were significantly higher in the PAAF-injected rats than in controls. Inhibition of NF-kappaB ameliorated the histologic findings and improved the survival rates. Our results suggest that PAAF play a role in the pathogenesis of lung injury in severe AP, at least in part through the activation of NF-kappaB.

Update on the management of acute severe pancreatitis

Acute severe pancreatitis is an aggressive disease with a mortality rate of up to 30 percent. In recent years therapy has shifted away from early surgery to intensive medical care. This article focuses on several issues of the management of acute severe pancreatitis emphasising evidence from recent clinical trials and recommendations from recent consensus conferences. Since a correct assessment of the severity of the disease is mandatory as early as possible in the treatment, several multiple scoring factor systems and individual risk factors are explained. The indications and the optimal timing of ERCP are discussed. Prophylactic administration of antibiotics, intravenously or by means of a selective digestive decontamination scheme, seems to be beneficial in decreasing morbidity but not mortality. Adequate nutritional support, preferably achieved by enteral feeding, is an important component in the supportive therapy. Protease inhibitors and anti-secretory drugs have not proven to be of benefit in improving outcome. Immunomodulating substances like platelet activating antagonists are promising but further studies are necessary to confirm the results of the early studies. Finally, indications for surgery are discussed.

Double blind, randomised, placebo controlled study of a platelet activating factor antagonist, lexipafant, in the treatment and prevention of organ failure in predicted severe acute pancreatitis

BACKGROUND

Platelet activating factor (PAF) is believed to amplify the activity of key mediators of the systemic inflammatory response syndrome (SIRS) in acute pancreatitis, resulting in multiorgan dysfunction syndrome. We tested the hypothesis that a potent PAF antagonist, lexipafant, could dampen SIRS and reduce organ failure in severe acute pancreatitis.

METHODS

We conducted a randomised, double blind, placebo controlled, multicentre trial of lexipafant (100 mg/24 hours intravenously for seven days commenced within 72 hours of the onset of symptoms) involving 290 patients with an APACHE II score >6. Power calculations assumed that complications would be reduced from 40% to 24%. Secondary end points studied included severity of organ failure, markers of the inflammatory response, and mortality rate.

FINDINGS

Overall, 80/138 (58%) patients in the placebo group and 85/148 (57%) in the lexipafant group developed one or more organ failures. The primary hypothesis was invalidated by the unexpected finding that 44% of patients had organ failure on entry into the study; only 39 (14%) developed new organ failure. Organ failure scores were reduced in the lexipafant group only on day 3: median change -1 (range -4 to +8) versus 0 (-4 to +10) in the placebo group (p=0.04). Systemic sepsis affected fewer patients in the lexipafant group (13/138 v 4/148; p=0.023). Local complications occurred in 41/138 (30%) patients in the placebo group and in 30/148 (20%) in the lexipafant group (20%; p=0.065); pseudocysts developed in 19 (14%) and eight (5%) patients, respectively (p=0.025). Deaths attributable to acute pancreatitis were not significantly different. Interleukin 8, a marker of neutrophil activation, and E-selectin, a marker of endothelial damage, decreased more rapidly in the lexipafant group (both p<0.05); however, absolute values were not different between the two groups.

INTERPRETATION

The high incidence of organ failure within 72 hours of the onset of symptoms undermined the primary hypothesis, and power calculations for future studies in severe acute pancreatitis will need to allow for this. Lexipafant had no effect on new organ failure during treatment. This adequately powered study has shown that antagonism of PAF activity on its own is not sufficient to ameliorate SIRS in severe acute pancreatitis

Fasting exacerbates acute pancreatitis by occlusion of the common bile duct in rats

We examined the effects of fasting and non-fasting on gallstone-related acute pancreatitis by the occlusion of the common bile duct (OCD). We prepared a rat OCD-induced pancreatitis model under both fasting and non-fasting conditions, and we measured amylase activity in ascites as well as production of inflammatory cytokines and chemokines. We also examined the pathology of the pancreas, myeloperoxidase (MPO) activity in some tissues and mortality rates. In the fasted OCD group, ascites containing a large amount of amylase, interleukin 1beta (IL-1beta), interleukin 6 (IL-6), and cytokine-induced neutrophil chemoattractant-1 (CINC-1) as well as marked hemorrhage and necrosis of the pancreatic acinar cells were observed. Pulmonary MPO activity increased 3.4-fold compared to the control group. In the non-fasted OCD group, there was no development of ascites. Slight necrosis of acinar cells and slight increases in pulmonary MPO activity were observed. In addition, in the fasted OCD group, the cumulative mortality rate was 50% 6 days after ligation. However, in the non-fasted OCD group, none of the animals died. These results suggest that gallstone-related severe pancreatitis depends on fasting-related structural and/or functional changes in the pancreas. Moreover, increased production of inflammatory cytokines and chemokines in ascites under fasting condition may be involved in multiple organ failure resulting from severe acute pancreatitis.

Activation of adenosine A1-receptor pathway induces edema formation in the pancreas of rats

BACKGROUND & AIMS

Adenosine has been shown to modulate various pathophysiologic conditions through receptor-mediated mechanisms. However, the role of adenosine in the pathogenesis of acute pancreatitis has not been described. We examined the effect of adenosine-receptor stimulation or inhibition on the pathologic changes of the pancreas.

METHODS

Rats received intraperitoneal injections of selective agonists of A1, A2a, and A3 adenosine receptors: 2-chloro-N(6)-cyclopentyladenosine (CCPA), CGS-21680 (CGS), or 1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-be ta-D-ribofuranuronamide (IB-MECA), respectively. Serum amylase activity and pathologic changes of the pancreas were evaluated. The effects of a specific A1-receptor antagonist (FK-838) on the pathologic findings of cerulein- and taurocholate-induced pancreatitis were also examined.

RESULTS

Administration of a selective A1 agonist induced hyperamylasemia and morphologic changes in the pancreas characterized by interstitial edema and leukocyte infiltration; neither A2a nor A3 agonist produced such changes. Treatment with an A1-receptor antagonist significantly attenuated the outcome induced by A1 agonist stimulation. In addition, the A1-receptor antagonist significantly ameliorated pancreatic edema in both pancreatitis models, although it did not improve the acinar cell damage of the pancreas or the increase of serum amylase.

CONCLUSIONS

Activation of the adenosine A1-receptor pathway may have an important role in the pathogenesis of acute pancreatitis.

Pancreatitis-associated ascitic fluid increases intracellular Ca(2+) concentration on hepatocytes

BACKGROUND

We have reported that pancreatitis-associated ascitic fluid (PAAF) contains a cytotoxic factor(s) inducing apoptosis on renal tubular cells and hepatocytes. It has been suggested that elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)) is associated with the development of cell damage and apoptosis.

METHODS

To clarify the mechanism of hepatocellular injury in acute pancreatitis, the effect of PAAF on hepatocyte [Ca(2+)](i) was investigated. Primary cultures of rat hepatocytes were loaded with Fura-2/acetoxymethyl, and the changes of [Ca(2+)](i) were measured using spectrofluorometer.

RESULTS

The baseline of hepatocyte [Ca(2+)](i) was 172 +/- 17 nM. [Ca(2+)](i) increased from 1 min after the addition of PAAF in a dose-dependent manner. Fractionation of PAAF revealed only one fraction (molecular weight >/= 5 x 10(4)) possessed both [Ca(2+)](i) elevation activity and cytotoxic activity. Neither 8-(N,N-diethyl-amino) octyl-3,4,5-trimethoxybenzoate (TMB-8) nor thapsigargin inhibited the PAAF-evoked [Ca(2+)](i) elevation. Chelation of extracellular Ca(2+) by ethylene glycol bis-(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) prevented the elevation of [Ca(2+)](i), but verapamil did not prevent it. Platelet-activating factor antagonist (TCV-309) blocked the PAAF-elicited [Ca(2+)](i) elevation. Pancreatitis-associated serum also increased hepatocyte [Ca(2+)](i). Moreover, PAAF increased [Ca(2+)](i) on Madin-Darby canine kidney cells in a dose-dependent manner.

CONCLUSIONS

These results suggest that the dramatic elevation of hepatocyte [Ca(2+)](i) due to PAAF may be closely related to the hepatocellular injury in severe acute pancreatitis and that platelet-activating factor may play a pivotal role in increasing hepatocyte [Ca(2+)](i). Elevation of [Ca(2+)](i) in various cells may be involved in the mechanism of multiple organ failure in this disease.

Inflammatory mediators in acute pancreatitis

Inflammatory mediators play a key role in acute pancreatitis and the resultant multiple organ dysfunction syndrome, which is the primary cause of death in this condition. Recent studies have confirmed the critical role played by inflammatory mediators such as TNF-alpha, IL-1beta, IL-6, IL-8, PAF, IL-10, C5a, ICAM-1, and substance P. The systemic effects of acute pancreatitis have many similarities to those of other conditions such as septicaemia, severe burns, and trauma. The delay between the onset of inflammation in the pancreas and the development of the systemic response makes acute pancreatitis an ideal experimental and clinical model with which to study the role of inflammatory mediators and to test novel therapies. Elucidation of the key mediators involved in the pathogenesis of acute pancreatitis will facilitate the development of clinically effective anti-inflammatory therapy.

Inflammatory mediators in acute pancreatitis

Inflammatory mediators play a key role in acute pancreatitis and the resultant multiple organ dysfunction syndrome, which is the primary cause of death in this condition. Recent studies have confirmed the critical role played by inflammatory mediators such as TNF-alpha, IL-1beta, IL-6, IL-8, PAF, IL-10, C5a, ICAM-1, and substance P. The systemic effects of acute pancreatitis have many similarities to those of other conditions such as septicaemia, severe burns, and trauma. The delay between the onset of inflammation in the pancreas and the development of the systemic response makes acute pancreatitis an ideal experimental and clinical model with which to study the role of inflammatory mediators and to test novel therapies. Elucidation of the key mediators involved in the pathogenesis of acute pancreatitis will facilitate the development of clinically effective anti-inflammatory therapy.

The scientific basis of medical therapy of acute pancreatitis. Could it work, and is there a role for lexipafant?

For a 30-year period beginning in 1958, the general basis of medical therapy of acute pancreatitis had as its focus the provision of supplementary antiprotease therapy usually given intravenously. This concept was based on the belief that the body's natural antiprotease defense mechanism, which relies heavily on alpha 2-macroglobulin, together with alpha 1-antiprotease (alpha 1-antitrypsin), was inadequate to cope with the vast enzyme release that occurred with the onset of the more severe forms of the disease. This article examines recent studies and emerging theories on the medical therapy of acute pancreatitis.

The potential role of therapeutic cytokine manipulation in acute pancreatitis

The central, detrimental role of the inflammatory cytokines IL-1 and TNF and the biologically active phospholipid PAF in the pathogenesis of AP has been established over the past 8 years. A number of antagonists to these mediators have been used successfully in the laboratory setting and are currently being examined in prospective randomized trials. The effectiveness of any antagonist depends not only on its ability to block the effects of the inflammatory mediators but also on its administration early enough in the course of the pancreatitis before pancreatic necrosis or organ dysfunction.

Role of oxidative stress in the pathogenesis of caerulein-induced acute pancreatitis

In the last decade, the role of oxidative stress has been extensively evaluated in different experimental models of acute pancreatitis. This review shows that there is strong evidence that this stress occurs as an early phenomenon in pancreatic tissue in the course of caerulein-induced acute pancreatitis. Oxidative stress was documented in pancreatic tissue by means of methods showing generation of reactive oxygen species (e.g., chemiluminescence) and accumulation of products of reactive oxygen species-mediated lipid peroxidation. with concomitant depletion of enzymatic and low molecular weight antioxidants. Features of acinar cell injury and inflammation, especially pancreatic edema, show a marked improvement following treatment with a broad spectrum of antioxidants, platelet activating factor antagonists, or donors of nitric oxide (NO). Unfortunately, in most cases these beneficial effects are temporary and generally restricted to an early phase of the disease. However, results of well-designed clinical trials should finally evaluate the importance of oxidative stress-oriented treatment in acute pancreatitis in humans.

Treatment with lexipafant ameliorates the severity of pancreatic microvascular endothelial barrier dysfunction in rats with acute hemorrhagic pancreatitis

CONCLUSION

Treatment with lexipafant reduced the severity of pancreatitis-associated endothelial barrier compromise, also associated with a decrease in systemic concentrations of interleukin (IL) 1. Thus, the present findings imply that platelet-activating factor (PAF) may play an important role in the pathogenesis of pancreatic endothelial dysfunction by signaling and triggering the production and release of certain cytokines.

BACKGROUND

Pancreatic capillary endothelial barrier dysfunction is an initial and characteristic feature of acute pancreatic injury and pancreatitis. PAF, a proinflammatory mediator and an intercellular signaling substance, has been considered to be involved in the inflammatory reaction and the systemic endothelial dysfunction of acute pancreatitis.

METHODS

The development of pancreatic capillary endothelial barrier dysfunction was monitored by tissue edema and exudation of plasma albumin into the interstitium, 3 and 12 h after induction of acute pancreatitis by intraductal infusion of 5% sodium taurodeoxycholate in rats. Pancreatic leukocyte recruitment was reflected by measuring myeloperoxidase activity. Serum levels of IL-1 beta and IL-6 were determined by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Pretreatment with lexipafant, a potent PAF receptor antagonist, significantly reduced the pancreatitis-induced increase in pancreatic endothelial barrier dysfunction, pancreatic leukocyte recruitment and serum levels of IL-1 beta, although a difference persisted between animals with sham operation and pancreatitis.

The Effect of Lexipafant on Bacterial Translocation in Acute Necrotizing Pancreatitis in Rats

Bacterial translocation (BT) from the gastrointestinal tract to mesenteric lymph nodes (MLNs) and other extra intestinal organs is an important source of infection in acute pancreatitis (AP). Lexipafant (BB-882) is a potent platelet-activating factor receptor antagonist that has an anti-inflammatory effect. To examine whether BB-882 could affect BT in acute necrotizing pancreatitis, 48 male Sprague Dawley rats (250–350 g) were studied. AP was induced in Group I and Group II by pressure injection of 3% taurocholate and trypsin into the common biliopancreatic duct (1 mL/kg of body weight). Group I rats received BB-882 (10 mg/kg, ip qd) and Group II rats received a similar volume of normal saline as a placebo postoperatively for 2 days. Group III and Group IV received BB-882 and placebo, respectively, after an exploratory laparotomy. At 48 hours postoperatively, blood was drawn for culture, serum amylase, and tumor necrosis factor (TNF)-α determinations. Specimens from MLNs, spleen, liver, pancreas, and cecum were harvested for culture of Gram-positive, Gram-negative, and anaerobic bacteria. Quantitative cecal cultures of Gram-positive, Gram-negative, and anaerobic bacteria were obtained. A point scoring system for five histological features that include interstitial edema, inflammatory cellular infiltration, fat necrosis, parenchymal necrosis, and hemorrhage was used to evaluate the severity of pancreatitis. There was no difference in serum amylase levels (2415 ± 127 IU/L versus 2476 ± 170 IU/L), serum TNF-α levels (7820 ± 1396 pg/mL versus 7318 ± 681 pg/mL), and the mean pancreatic histology score (5.9 ± 1.2 versus 6.5 ± 1.1) between Group I and Group II, respectively (P gt 0.05). Seven of 12 Group I rats had BT to MLNs, compared with 11 of 12 rats in Group II (P > 0.05). Five of 12 Group I rats had BT to distant sites such as pancreas, spleen, liver, and/or blood, compared with 11 of 12 rats in Group II (P < 0.05). BB-882 treatment decreases bacterial spread to distant sites, but does not reduce serum amylase levels and serum TNF-α levels or ameliorate pancreatic damage in rats with AP.

Treatment with lexipafant ameliorates the severity of pancreatic microvascular endothelial barrier dysfunction in rats with acute hemorrhagic pancreatitis

CONCLUSION

Treatment with lexipafant reduced the severity of pancreatitis-associated endothelial barrier compromise, also associated with a decrease in systemic concentrations of interleukin (IL) 1. Thus, the present findings imply that platelet-activating factor (PAF) may play an important role in the pathogenesis of pancreatic endothelial dysfunction by signaling and triggering the production and release of certain cytokines.

BACKGROUND

Pancreatic capillary endothelial barrier dysfunction is an initial and characteristic feature of acute pancreatic injury and pancreatitis. PAF, a proinflammatory mediator and an intercellular signaling substance, has been considered to be involved in the inflammatory reaction and the systemic endothelial dysfunction of acute pancreatitis.

METHODS

The development of pancreatic capillary endothelial barrier dysfunction was monitored by tissue edema and exudation of plasma albumin into the interstitium, 3 and 12 h after induction of acute pancreatitis by intraductal infusion of 5% sodium taurodeoxycholate in rats. Pancreatic leukocyte recruitment was reflected by measuring myeloperoxidase activity. Serum levels of IL-1 beta and IL-6 were determined by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Pretreatment with lexipafant, a potent PAF receptor antagonist, significantly reduced the pancreatitis-induced increase in pancreatic endothelial barrier dysfunction, pancreatic leukocyte recruitment and serum levels of IL-1 beta, although a difference persisted between animals with sham operation and pancreatitis.

Inhibition of nuclear factor-kappaB activation improves the survival of rats with taurocholate pancreatitis

BACKGROUND

Death in the early stages of severe acute pancreatitis is frequently the result of multiple organ dysfunction, but its mechanism is not clear.

AIMS

To investigate the state of nuclear factor-kappaB (NF-kappaB) in macrophages of rats with lethal pancreatitis, and to assess the effectiveness of pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB, on the pathology and mortality.

METHODS

Taurocholate pancreatitis was produced in rats, and the severity of the disease, the mortality, and activation of NF-kappaB in peritoneal and alveolar macrophages were compared in rats receiving pyrrolidine dithiocarbamate (PDTC) treatment and those that were not.

RESULTS

Taurocholate pancreatitis produced massive necrosis, haemorrhage, and severe leucocyte infiltration in the pancreas as well as alveolar septal thickening in the lung. NF-kappaB was activated in peritoneal and alveolar macrophages six hours after pancreatitis induction. Pretreatment with PDTC dose-dependently attenuated the NF-kappaB activation and improved the survival of the rats, although it did not affect the early increase in serum amylase and histological findings.

CONCLUSIONS

Early blockage of NF-kappaB activation may be effective in reducing fatal outcome in severe acute pancreatitis.