Treatment of acute pancreatitis. Comparison of animal and human studies

Methodical advances in reproducibility research: A proof of concept qualitative comparative analysis of reproducing animal data in humans

BACKGROUND

While the term reproducibility crisis mainly reflects reproducibility of experiments between laboratories, reproducibility between species also remains problematic. We previously summarised the published reproducibility between animal and human studies; i.e. the translational success rates, which varied from 0% to 100%. Based on analyses of individual factors, we could not predict reproducibility. Several potential analyses can assess effect of combinations of predictors on an outcome. Regression analysis (RGA) is common, but not ideal to analyse multiple interactions and specific configurations (≈ combinations) of variables, which could be highly relevant to reproducibility. Qualitative comparative analysis (QCA) is based on set theory and Boolean algebra, and was successfully used in other fields. We reanalysed the data from our preceding review with QCA.

RESULTS

This QCA resulted in the following preliminary formula for successful translation: ∼Old*∼Intervention*∼Large*MultSpec*Quantitative Which means that within the analysed dataset, the combination of relative recency (∼ means not; >1999), analyses at event or study level (not at intervention level), n < 75, inclusion of more than one species and quantitative (instead of binary) analyses always resulted in successful translation (>85%). Other combinations of factors showed less consistent or negative results. An RGA on the same data did not identify any of the included variables as significant contributors.

CONCLUSIONS

While these data were not collected with the QCA in mind, they illustrate that the approach is viable and relevant for this research field. The QCA seems a highly promising approach to furthering our knowledge on between-species reproducibility.

Animal to human translation: a systematic scoping review of reported concordance rates

Background

Drug development is currently hampered by high attrition rates; many developed treatments fail during clinical testing. Part of the attrition may be due to low animal-to-human translational success rates; so-called “translational failure”. As far as we know, no systematic overview of published translational success rates exists.

Systematic scoping review

The following research question was examined: “What is the observed range of the animal-to-human translational success (and failure) rates within the currently available empirical evidence?”. We searched PubMed and Embase on 16 October 2017. We included reviews and all other types of “umbrella”-studies of meta-data quantitatively comparing the translational results of studies including at least two species with one being human. We supplemented our database searches with additional strategies. All abstracts and full-text papers were screened by two independent reviewers. Our scoping review comprises 121 references, with various units of measurement: compound or intervention (k = 104), study/experiment (k = 10), and symptom or event (k = 7). Diagnostic statistics corresponded with binary and continuous definitions of successful translation. Binary definitions comprise percentages below twofold error, percentages accurately predicted, and predictive values. Quantitative definitions comprise correlation/regression (r²) and meta-analyses (percentage overlap of 95% confidence intervals). Translational success rates ranged from 0 to 100%.

Conclusion

The wide range of translational success rates observed in our study might indicate that translational success is unpredictable; i.e. it might be unclear upfront if the results of primary animal studies will contribute to translational knowledge. However, the risk of bias of the included studies was high, and much of the included evidence is old, while newer models have become available. Therefore, the reliability of the cumulative evidence from current papers on this topic is insufficient. Further in-depth “umbrella”-studies of translational success rates are still warranted. These are needed to evaluate the probabilistic evidence for predictivity of animal studies for the human situation more reliably, and to determine which factors affect this process.

Adaptive Immune Cell Dysregulation and Role in Acute Pancreatitis Disease Progression and Treatment

Acute pancreatitis (AP) is an inflammation of the pancreas caused by various stimuli including excessive alcohol consumption, gallstone disease and certain viral infections. Managing specifically the severe form of AP is limited due to lack of an understanding of the complex immune events that occur during AP involving immune cells and inflammatory molecules such as cytokines. The relative abundance of various immune cells resulting from the immune dysregulation drives disease progression. In this review, we examine the literature on the adaptive immune cells in AP, the prognostic value of these cells in stratifying patients into appropriate care and treatment strategies based on cell frequency in different AP severities are discussed.

Acute Pancreatitis: Work-up and Management

Acute pancreatitis is still a common clinical entity that causes significant morbidity and mortality. The most common etiological associations include chronic al coholism, biliary tract disease, iatrogenic (e.g., endo scopic retrograde cholangiopancreatography-induced), hypertriglyceridemia, and idiopathic varieties. New radiological techniques such as dynamic pancreatog raphy appear to be useful in diagnosing and determin ing the extent of necrotizing pancreatitis. Biochem ical variables such as the C-reactive protein and the trypsinogen-activated peptide seem promising in de tecting severe disease within the first few days of hospi talization. Computed tomographic-guided percutane ous aspiration of phlegmonous pancreatitis may be helpful in differentiating infected from noninfected masses. Although current studies have not identified any pharmacological agent as efficacious in improving sur vival, emergency sphincterotomy and removal of im pacted gallstones in severe gallstone pancreatitis may be beneficial in this regard. Prolonged (i.e., 7 day) perito neal dialysis may reduce the severity of pancreatic sep sis. Surgical drainage of infected fluid collections such as abscesses is a well-accepted adjunct to medical therapy. Surgical necrosectomy for necrotizing pancreatitis, however, which is advocated in some aggressive surgi cal units, is not yet commonplace and its role needs to be determined in controlled studies.

Immune cells and immune-based therapy in pancreatitis

Alcohol and gallstones are the most common etiologic factors in acute pancreatitis (AP). Recurrent AP can lead to chronic pancreatitis (CP). Although the underlying pathophysiology of the disease is complex, immune cells are critical in the pathogenesis of pancreatitis and determining disease severity. In this review, we discuss the role of innate and adaptive immune cells in both AP and CP, potential immune-based therapeutic targets, and animal models used to understand our knowledge of the disease. The relative difficulty of obtaining human pancreatic tissue during pancreatitis makes animal models necessary. Animal models of pancreatitis have been generated to understand disease pathogenesis, test therapeutic interventions, and investigate immune responses. Although current animal models do not recapitulate all aspects of human disease, until better models can be developed available models are useful in addressing key research questions. Differences between experimental and clinical pancreatitis need consideration, and when therapies are tested, models with established disease ought to be included.

High-dose versus low-dose octreotide in the treatment of acute pancreatitis: a randomized controlled trial

To evaluate the therapeutic efficacy of high-dose octreotide in patients with predicted severe acute pancreatitis (SAP) or SAP, two hundred and thirty-six patients with predicted SAP and 136 patients with SAP were randomized into control, high-dose octreotide (High-O) and low-dose octreotide (Low-O) groups. In addition to the conventional managements administrated in control group, High-O group received an intravenous infusion of octreotide at 50 μg/h × 3d + 25 μg/h × 4d, and Low-O group received octreotide at 25 μg/h × 7d. The major primary outcomes included the numbers of predicted SAP patients which developed SAP after intervention and the number of patients with SAP amelioration. Secondary outcomes included APACHE II, SIRS scores, plasma levels of somatostatin (SST), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6). There were no significant differences between the control and Low-O groups in terms of prevention and treatment for SAP. The incidence of SAP in patients with predicted SAP who received High-O was significantly lower than the Low-O group: 37.5% vs. 59.8%, p=0.005. Compared with Low-O group, the number of SAP patients in the SAP arm in the High-O group was reduced by 29.8%. Plasma levels of SST in both predicted SAP and the SAP patients were efficiently recovered (from 132.71±31.40 pg/ml to 180.00±23.50 pg/ml, p<0.05) after high-dose octreotide supplementation, which concomitantly reduced TNF-α and IL-6 levels. High-dose octreotide administration within 48h after AP onset may efficiently reduce the risk of SAP developing and partly attenuate SAP through raising plasma SST to a normal level and decreasing IL-6 and TNF-α.

Aprotinin in severe acute pancreatitis

Aprotinin, a Kunitz protease inhibitor, has a wide inhibitory action with particular activity against trypsin, chymotrypsin and kallikrein, making it theoretically attractive in ameliorating the effects of acute pancreatitis. Its use in acute pancreatitis has been studied for the last 50 years with disappointing results. In this paper, we review the previous studies and argue that all the studies have not been adequately powered, have inappropriate end-points, but most importantly have not attained adequate plasma and peritoneal levels of aprotinin to produce sufficient inhibitory activity. We hypothesise that a well-powered study with adequate aprotinin dosing may clarify its clinical benefit in severe acute pancreatitis.

Prediction of severe acute pancreatitis: Current knowledge and novel insights

Acute pancreatitis (AP) is a common and potentially lethal acute inflammatory process with a highly variable clinical course. It is still unclear why some patients progress to organ failure and others do not. Ability to predict which patients will develop severe disease is limited. Routine clinical and laboratory data and multi-factorial clinical scores measured on admission and during the first 48 h of hospitalization are currently the standards of care used to estimate the magnitude of the inflammatory response to injury. Current literature highlights several common environmental, metabolic and genetic factors that increase the risk of AP development and subsequent adverse sequelae. Several cytokines have been found to play a critical role in the pathogenesis of AP by driving the subsequent inflammatory response, to include tumor necrosis factor-α (TNF-α), Interleukin-1 (IL-1), IL-6 and monocyte chemotactic protein-1 (MCP-1). Large, prospective studies are still needed to address these questions by identifying AP risk factors and serum biomarkers of severe disease.

Pentoxifylline attenuates pulmonary inflammation and neutrophil activation in experimental acute pancreatitis

OBJECTIVES

Acute pancreatitis (AP) is associated with a systemic inflammatory response. Pentoxifylline (PTX) has been shown to attenuate neutrophil activation and end-organ injury in shock states such as hemorrhage and sepsis. We hypothesized that PTX would down-regulate AP-induced lung injury.

METHODS

Sprague-Dawley rats underwent catheterization of the pancreatic duct. Acute pancreatitis (n = 7) and AP/PTX animals (n = 7) received a retrograde infusion of 3.5% sodium taurocholate and intravenous treatment with normal saline or normal saline and PTX (25 mg/kg), respectively. Pulmonary neutrophil degranulation and sequestration were determined by zymography and detection of myeloperoxidase. Nuclear factor kappa B and mitogen-activated protein kinase phosphorylation was determined by Western blot. Cytokine-induced neutrophil chemoattractant was quantified by enzyme linked immunosorbent assay.

RESULTS

Pulmonary histologic injury scores were attenuated in the AP/PTX group (P < 0.05). Plasma amylase levels remained unchanged. Pentoxifylline produced a significant decline in myeloperoxidase content and matrix metalloproteinase activity (P < 0.05). The increase in the phosphorylation of pulmonary nuclear factor kappa B, p38 mitogen-activated protein kinase, and extracellular-related signal kinase 1/2 observed after AP was not demonstrated with PTX (P < 0.05). Pentoxifylline supplementation reduced pulmonary cytokine-induced neutrophil chemoattractant levels by 50% (P < 0.05).

CONCLUSIONS

Pentoxifylline significantly attenuated histologic lung injury, pulmonary neutrophil activity, and proinflammatory signaling in a severe model of AP. Therefore, PTX may serve as an adjunct for the treatment of the inflammatory complications of severe AP.

Pathophysiology and treatment of acute pancreatitis: new therapeutic targets--a ray of hope?

Acute pancreatitis is a life-threatening disease with putatively high mortality rates, particularly in the setting of systemic inflammatory response and multiple organ failure when superinfection of necrosis occurs. Although the APACHE II and Ranson score are widely accepted as clinical scores to predict the prognosis, current medical treatment is still based upon state of the art intensive care treatment largely unrelated to the pathogenesis of the disease. The mechanisms by which premature enzyme activation and autodigestion of the pancreatic gland is triggered and maintained are still ill-defined. It is well known that activation of chemokines, cytokines and pancreatic enzymes characterize the cause of the disease, but disease-phase specific treatment attempts have thus far not resulted in successful molecular based medical treatments. The current summary describes the novel understanding in the pathophysiology of acute pancreatitis with special emphasis on specific disease phases. It outlines promising and novel experimental and medical therapeutic approaches which might become clinical targets and successful strategies to significantly reduce pancreatitis-associated mortality rates.

Effect of a selective inhibitor of secretory phospholipase A2, S-5920/LY315920Na, on experimental acute pancreatitis in rats

We investigated the efficacy of a potent inhibitor of secretory phospholipase A2 (sPLA2), S-5920/LY315920Na, in an experimental model of acute pancreatitis in rats. Combined intraductal injection of sodium taurocholate (5 mg/rat) and porcine pancreatic sPLA2-IB (300 microg/rat) caused severe hemorrhagic necrotizing pancreatitis resulting in high mortality, along with rapid increases of catalytic PLA2 and lipase activities in plasma and ascites and with gradual increases of plasma amylase and aspartate aminotransferase levels over 9 h after the pancreatitis. Prophylactic intravenous treatment with S-5920/LY315920Na significantly reduced mortality at 7 days, and strongly abrogated PLA2 activities in both plasma and ascites along with significant reduction of lipase activity, amylase, aspartate aminotransferase, and hemorrhage at 6 h. It also significantly reduced histological damage such as edema and parenchymal and fat necroses of the pancreatic tissue. This sPLA2 inhibitor could become an effective agent for the treatment of severe acute pancreatitis.

[Therapy of chronic pancreatitis]

Treatment of chronic pancreatitis is dependend on the stage of the disease and its complications. Pain therapy should be based on the knowledge of various causes of pain. In therapy of complications such as bile duct or pancreatic duct strictures interventional endoscopy is usually the first choice followed by surgery. Exocrine insufficiency is treated by porcine pancreatic extracts, endocrine insufficiency by insulin. One has to apply various imaging procedures such as sonography, MRCP, ERCP, endosonography, CT for exact diagnosis of complications and planning various therapeutic strategies. Pseudocysts may be drained via the transgastric, transduodenal, transpapillary or transcutaneous route. Distal prepapillary stenosis of the main pancreatic duct and bile duct stenoses can be drained by stents. Pancreatic duct stones can be desintegrated by shock waves and removed by endoscopy. Early diagnosis of pancreatic carcinoma as a potential complication of long standing inflammation of the pancreas remains an unsolved problem.

Hereditary pancreatitis: a model for understanding the genetic basis of acute and chronic pancreatitis

Progress in understanding pancreatic diseases has been limited by a number of factors. Primary problems include the absence of good animal models, and difficulty in understanding the origin of pancreatic disease since the disease is usually manifest by the progressive destruction of the gland itself. Beginning in 1995, our laboratory, with the support of the Midwest Multicenter Pancreatic Study Group, began investigating the genetic basis of hereditary pancreatitis. Utilization of information becoming available through the human genome project allowed us to map and identify the hereditary pancreatitis gene as cationic trypsinogen (PRSS1). Molecular modeling, and subsequent experimental evidence, has solved key elements of the mysteries surrounding the origin of acute pancreatitis and the progression of acute pancreatitis to chronic pancreatitis. The availability of new genetic information and genomic tools should produce a revolution in our understanding of pancreatic diseases.

Site-specific therapeutic effects of protease inhibitors: effect of route of administration in experimental pancreatitis

Inappropriate local and systemic activation of trypsin arising from trypsinogen mediates key steps in the pathogenesis of acute pancreatitis. Trypsin presumably causes direct injury to cells, but also activates other proteases and causes secondary effects such as inducing the expression of adhesion molecules on endothelium and leukocytes, and stimulating leukocytes to secrete cytokines, tissue-damaging enzymes, oxygen radicals and matrix metalloproteinases. Protease inhibition interferes with this cascade of events. Here we review experimental studies on protease inhibition and their potential application and report our findings of site-specific therapeutic effects of the novel protease inhibitor nafamostat (FUT-175) in experimental acute pancreatitis.

Hereditary pancreatitis: a model for inflammatory diseases of the pancreas

Acute and chronic pancreatitis remain among the most recalcitrant of all diseases to investigation and intervention. In the majority of patients, excessive alcohol consumption is associated with development of the disease. Therefore, several theories have been proposed seeking to explain the relationship between alcohol and the development of acute and chronic pancreatitis. However, recent investigations in hereditary pancreatitis provided important insights into chronic pancreatitis pathogenesis and offer an important model for understanding pancreatic inflammation. This article highlights several advances gained from investigating hereditary pancreatitis kindreds, and reviews the TIGAR-O risk/aetiology classification system. Finally, the major independent theories on development of chronic pancreatitis are reviewed with respect to the SAPE hypothesis of chronic pancreatitis pathogenesis.

Optimising outcomes in acute pancreatitis

Acute pancreatitis is a common cause for presentation to emergency departments. Common causes in Western societies include biliary pancreatitis and alcohol (the latter in the setting of chronic pancreatitis). Acute pancreatitis also follows endoscopic retrograde pancreatography in 5 to 10% of patients, a group that could potentially benefit from prophylactic treatment. Although episodes of pancreatitis usually run a relatively benign course, up to 20% of patients have more severe disease, and this group has significant morbidity and mortality. Therefore, attempts have been made to identify, at or soon after presentation, those patients likely to have a poor outcome and to channel resources to this group. The mainstay of treatment is aggressive support and monitoring of those patients likely to have a poor outcome. Pharmacotherapy for acute pancreatitis (both prophylactic and in the acute setting) has been generally disappointing. Efforts initially focused on protease inhibitors, of which gabexate shows some promise as a prophylactic agent. Agents that suppress pancreatic secretion have produced disappointing results in human studies. Infection of pancreatic necrosis is associated with high mortality and requires surgical intervention. In view of the seriousness of infected necrosis, the use of prophylactic antibacterials such as carbapenems and quinolones has been advocated in the setting of pancreatic necrosis. Similarly, data are accumulating to support the use of prophylactic antifungal therapy. Recently, it has become apparent that the intense inflammatory response associated with acute pancreatitis is responsible for much of the local and systemic damage. With this realisation, future efforts in pharmacotherapy are likely to focus on suppression or antagonism of pro-inflammatory cytokines and other inflammatory mediators. Similarly, animal studies have demonstrated the importance of oxidative stress in acute pancreatitis, although to date there is a paucity of information regarding the efficacy of antioxidants. Although the clinical course for most patients with acute pancreatitis is mild, severe acute pancreatitis continues to be a clinical challenge, requiring a multidisciplinary approach of physician, intensivist and surgeon.

Pancreatic polypeptide in pancreatitis

Pancreatitis is a disease with increasing incidence which can be divided into an acute and a chronic form. In both acute and chronic pancreatitis, changes in plasma concentration of pancreatic polypeptide (PP) and its regulation have been reported. In daily clinical work a serologic test for the precise diagnosis and staging of acute and chronic pancreatitis is still desirable. Therefore, many studies have investigated plasma concentrations of PP in acute and chronic pancreatitis as a diagnostic marker and as a therapeutic option to treat pancreatogenic diabetes mellitus. Although the study results are presently inconclusive and potentially contradictory, the findings are nevertheless encouraging, and indicate that PP might have a role in diagnosis, grading and estimation of the prognosis of pancreatitis. Further data and prospective controlled studies are needed to judge whether PP is of clinical value for diagnosing, staging and predicting long-term outcome in acute and chronic pancreatitis.

Accelerated radiochemotherapy in pancreatic cancer is not necessarily related to a pathologic pancreatic function decline in the early period

PURPOSE

To evaluate the functional effects of ionizing radiation in patients with unresectable pancreatic cancer in the early period after accelerated radiochemotherapy (ART).

METHODS AND MATERIALS

To analyze the exocrine component, the amino acid consumption test and fecal elastase 1 were performed in 13 patients immediately before and 4-8 weeks after ART. Pancreatic duct morphology was evaluated before therapy. Weight loss and clinical steatorrhea were recorded. Endocrine parameters were examined according to standardized criteria.

RESULTS

The relative change of the amino acid consumption test results and the median elastase concentration was 41.2% and 56.4%, respectively. Five patients still had normal test results after ART and 5 patients developed pathologic values. The median relative weight loss of the total body weight was 7.7% +/- 4.5%. No steatorrhea occurred. Of the 5 patients with normal values, 3 had a mean organ dose of <40 Gy. Of the 5 patients with pathologic values, 4 had a mean organ dose of >41 Gy. The endocrine function measurements remained unchanged.

CONCLUSION

Although a nominal reduction of exocrine function parameters occurred in most patients, ART was not necessarily related to a pathologic level in the early period. Diabetes was not established. The functional impairment that was existent in the patient population presumably contributed to the weight loss. Pancreatic enzyme preparations may also play a role in maintaining an anabolic state during and after radiochemotherapy.

Regional effects of nafamostat, a novel potent protease and complement inhibitor, on severe necrotizing pancreatitis

BACKGROUND

We evaluated the effect of the novel protease inhibitor nafamostat on rat necrotizing pancreatitis through different routes of administration.

METHODS

Three hours after the induction of severe pancreatitis, the rats received intravenous gabexate or intravenous or local mesenteric intra-arterial nafamostat. At 9 hours, ascites and bronchoalveolar lavage fluid were collected for the evaluation of capillary leakage (Evans blue extravasation). Pancreas and lung were excised for histologic features, myeloperoxidase, and trypsinogen activation peptide. Twenty-four hour survival was evaluated.

RESULTS

Only the intravenous infusion of nafamostat significantly reduced myeloperoxidase (11.7 +/- 2.3 vs 18.3 +/- 1.8 mU/mg; P <.05) and capillary leakage in lungs (Evans blue dye, 1.6 +/- 0.3 vs 2.6 +/- 0.3; P <.05). Only intra-arterial infusion of nafamostat significantly diminished capillary peritoneal leakage (Evans blue dye, 3.6 +/- 0.9 vs 9.4 +/- 0.4; P <.01). Typsinogen activation peptide levels were significantly reduced in all groups, but only intra-arterial infusion did so to baseline. Histologic inflammation in the pancreas was most significantly reduced after intra-arterial infusion (0.92 +/- 0.08 vs 2.91 +/- 0.06; P <.05). No form of protease inhibition reduced mortality rates.

CONCLUSIONS

The effects of protease inhibition depend on the route of administration. Nafamostat has maximal effects on the pancreas and peritoneal capillary leakage when delivered by way of local intra-arterial infusion, and shows a greater reduction of lung leukocyte infiltration and capillary leakage by the intravenous route. Nafamostat is more effective than gabexate.

Randomized, placebo-controlled trial of lazaroid effects on severe acute pancreatitis in rats

OBJECTIVES

To evaluate the therapeutic potential of lazaroids in severe necrotizing acute pancreatitis and to investigate the association between oxidative stress, protease activation, and local production of proinflammatory cytokines and the severity and lethality of the disease.

BACKGROUND

Oxidative stress is a crucial factor in the pathophysiology of acute pancreatitis and its systemic complications. Treatment with antioxidants, however, failed to improve survival in most studies performed so far. Lazaroids are a novel class of antioxidants that potently protect pancreatic acinar cells against oxidant attack in vitro.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

University research laboratory.

SUBJECTS

Seventy-five anesthetized male Wistar rats (300-350 g).

INTERVENTIONS

Severe acute pancreatitis was induced by retrograde injection of 3.5% taurocholate-sodium into the common bile-pancreatic duct. Interventions were performed to mimic the clinical situation, including continuous intravenous fluid substitution and administration of lazaroids in a therapeutic protocol. Therapy was started 1 hr after injection of the bile salt by using three different lazaroids, lactated Ringer's solution (placebo), and methylprednisolone as a corticosteroid control (n = 15 in each group). All the substances were given by continuous intravenous infusion throughout the 20-hr trial period.

MEASUREMENTS AND MAIN RESULTS

Pancreatic homogenates and ascites were analyzed for indicators of oxidative stress, antioxidants, proteases, and proinflammatory cytokines. Pancreatic edema, morphologic pancreatitis severity, and pancreatic histopathology also were assessed. All three lazaroids and methylprednisolone diminished pancreatic tumor necrosis factor-alpha concentrations. Lethality was 33% in the placebo group. Neither the lazaroids nor methylprednisolone influenced survival. The local pancreatic and peritoneal concentrations of lipid peroxidation products, antioxidants, and proteases did not differ among the five groups. Nonsurviving rats, however, had a higher total protease activity in the pancreas and higher concentrations of trypsinogen activation peptide in ascites, as compared with surviving animals. There were no differences between survivors and nonsurvivors with regard to variables of oxidative stress and cytokines.

CONCLUSIONS

Lazaroid application under clinically relevant conditions (i.e., after induction of fulminant acute pancreatitis) does not influence lethality or biochemical variables relevant to this disease. Protease activation rather than oxidative stress or local pancreatic cytokine production is an important determinant of disease severity and survival in acute pancreatitis. In experimental studies evaluating novel therapeutics, the same strict criteria should be applied as in the human setting.

Hereditary pancreatitis and mutations of the cationic trypsinogen gene

BACKGROUND

Mutations of the cationic trypsinogen gene have been detected in hereditary pancreatitis. This article reviews current understanding of their function and clinical significance.

METHODS

An unrestricted Medline search was conducted using the key words hereditary pancreatitis and 'cationic trypsinogen . Additional material was obtained from references cited in original papers and recently published abstracts of meetings.

RESULTS AND CONCLUSION

Cationic trypsinogen mutations have been identified in most, but not all, families with hereditary pancreatitis. This confirms existing evidence that premature trypsinogen activation plays a central role in the pathogenesis of human pancreatitis. Patients currently clinically defined as having hereditary pancreatitis should be screened for the presence of cationic trypsinogen mutations. A subgroup of patients with non-hereditary pancreatitis may also benefit from being screened for these mutations. Patients with hereditary pancreatitis should be entered into prospective, multicentre trials investigating secondary screening for pancreatic cancer. Gene therapy for hereditary pancreatitis is beyond current technological capability but remains a future therapeutic prospect for this often debilitating condition.

Genetic predispositions to acute and chronic pancreatitis

Advances in molecular genetics have provided the powerful tools necessary to identify the key molecules and mechanisms that underly the disease process. Continued work in this area promises to reveal new insights as new disease genes are discovered. This article focuses on the insights into the cause of acute and chronic pancreatitis gained by investigation of the HP genes, the diagnosis of the known mutations, the fascinating observation of nonpenetrance, and a look at future directions.

The effects of somatostatin and octreotide on experimental and human acute pancreatitis

The role of somatostatin and octreotide for AP has been studied for two decades, yet the data still remain inconclusive. The inconsistencies of the results of experimental studies and clinical trials may stem from the fact that the optimal therapeutic modality has not been determined. Furthermore, although they are similar in structure and physiologic activities, the mechanisms of action and effects of somatostatin and octreotide in AP may be different. Because the data are sparse, most reports, primarily those in the English literature, on the efficacy of somatostatin and octreotide in the management of AP were reviewed. Included are both nonrandomized and prospective, double-blind, clinical trials and studies on the effects of these agents on various experimental models of the disease. The results of the studies on somatostatin and octreotide are presented and discussed separately, with specific reference to the experimental and treatment details. The main focus of the review is the effect of subcutaneous and intravenous administration of octreotide. Analysis of the data suggests that somatostatin could not be recommended for AP and that the efficacy of subcutaneous administration of octreotide is also questionable. Theoretically, intravenous octreotide may be more appropriate for this condition, but recent results with this therapeutic method are limited and contradictory. Studies that would delineate the optimal therapeutical modality and the patient population most likely to respond to the treatment are prerequisite for large-scale clinical trials on the effects of octreotide on human pancreatitis.

Inhibition of kinin action and kinin generation compared to dexamethasone pretreatment with respect to vascular effects and pancreatic enzymes in experimental acute pancreatitis

It was determined earlier that inhibition of the action of endogenous kinins by the bradykinin B2 antagonist, icatibant (Hoe-140; D-Arg-[Hyp3, Thi5, D-Tic7, Oic8]-bradykinin), prevents pancreatic oedema formation during caerulein-induced acute pancreatitis, and simultaneously improves the egress of activated pancreatic enzymes from the pancreas. We have now investigated whether inhibition of increases in vascular permeability by another approach, i.e., pretreatment with dexamethasone, would have comparable effects. In addition, preliminary data are presented on the effects of the selective low molecular weight inhibitor of tissue kallikrein, H-(4-Cl)-D-Phe-1Nal-(3-aminopropyl)-guanidine (CH-2856). Icatibant abolished plasma extravasation into the pancreatic tissue and prevented the development of hypovolaemia. Caerulein-induced increases of amylase activity in the pancreas were significantly reduced by icatibant, while amylase activity in blood was augmented. Inhibition of kinin generation by CH-2856 had similar effects, as oedema formation was inhibited and enzyme activities were reduced in the pancreas and augmented in the blood serum. Dexamethasone completely abolished oedema formation, but only partially inhibited the development of hypovolaemia and haemoconcentration. Amylase activities in the pancreas and in blood remained completely unaffected by dexamethasone. The results suggest that retention of activated enzymes in the pancreatic tissue during acute pancreatitis involves a B2 receptor-mediated, but glucocorticoid-insensitive mechanism.

The spectrum of complications of hereditary pancreatitis. Is this a model for future gene therapy?

Hereditary pancreatitis is an unusual form of acute and chronic pancreatitis that is usually associated with two specific mutations in the cationic trypsinogen gene. The extensive information available on the biochemistry, cell biology, and molecular biology of cationic trypsinogen and its gene provides the groundwork for development of a variety of therapeutic strategies, including gene therapy. Several features of this disease, however, make gene therapy unlikely in the near future. Further research using new models, including transgenic animals, is required before breakthroughs in therapy can be expected.

Complicated Acute Pancreatitis

The treatment of severe, complicated pancreatitis requires: Rapid assessment and recognition of severity, determined by using APACHE or equivalent scoring systems. Aggressive resuscitation with crystalloid and colloid solutions using central venous monitoring for guidance, and to help identify and treat early organ failure. Nutritional support including total parenteral feeding, which can assist in maintaining nutrition during the prolonged period that may ensue. Nasojejunal feedings, bypassing the duodenum, supply nutrition and may decrease infectious complications. Judicious use of imaging studies, mainly dynamic-bolus contrast computed tomography (CT) of the abdomen. These studies will identify necrosis and other local complications of pancreatitis that are treatable by endoscopic, radiological or surgical means. Antibiotics, whose role has evolved to that of prophylaxis to prevent infection of necrotizing pancreatitis. Other medications such as octreotide have a limited role in the management of certain specific complications such as fistulas and post-pancreatic surgery. A multidisciplinary approach, including the use of endoscopic techniques and surgery to treat complicated pancreatitis. This approach provides optimal care of this challenging group of patients.

The therapeutic effect of hypertonic solutions on the changes in the effective circulating plasma volume in acute necrotizing pancreatitis in rats

While hypovolemia or hypovolemic shock is dominant in the early stage of severe acute pancreatitis, there have been few studies on the effects of hypertonic solutions in the management of this disease. We conducted this study to evaluate the therapeutic effects of hypertonic saline solutions (HS) on the course of severe acute pancreatitis in rats. Pancreatitis was induced in male Wistar rats by injecting a 5% solution of sodium taurocholate into the biliopancreatic duct. The effective circulating plasma volume (ECPV) was measured using radioiodinated [125I]bovine serum albumin. Samples of blood and of ascitic fluid were obtained 3, 6, and 12 h after the onset of pancreatitis. Lactated Ringer's solution (LR) and HS were administered consecutively for 3 h beginning 3 h after the induction of pancreatitis. ECPV was measured 6 h after the onset of pancreatitis. The survival rates were investigated for up to 10 days. The mean ECPV decreased significantly from 24.9 +/- 1.1 ml/kg before disease onset to 11.5 +/- 1.3 ml/kg 6 h postoperatively. LR failed to achieve a normal value for ECPV even following a 150 ml/kg infusion. HS200 and HS300 restored the ECPV to the normal level, and with smaller volumes infused. All rats in the untreated group died within 3 days. LR and HS improved the survival rates, with the infusion of HS200, 100 ml/kg, thus attaining a 45% survival at 10 days.

Beneficial effect of octreotide treatment in acute pancreatitis in rats

CONCLUSIONS

Octreotide treatment contributes to the regulation of tumor necrosis factor (TNF) production in sodium taurocholate-induced acute necrotizing pancreatitis in rats. Owing to its complex effect, octreotide can partially ameliorate the deleterious consequences of acute necrotizing pancreatitis. Elevated TNF and interleukin-6 (IL-6) levels in the peritoneal fluid may be considered a consequence of the activation of peritoneal macrophages.

BACKGROUND

The effects of octreotide on exocrine pancreatic function have been investigated in numerous studies, but little attention has been paid to its influence on cytokine production in acute pancreatitis.

METHODS

Acute pancreatitis was induced by the retrograde injection of taurocholic acid into the pancreatic duct in male Wistar rats. Serum amylase activity, wet pancreatic weight/body weight (pw/bw) ratio, and TNF and IL-6 levels were measured. Four micrograms/kg of octreotide was administered subcutaneously at the time of induction of pancreatitis and 24 or 48 h later. Rats were sacrificed 6, 24, 48, or 72 h after the operation.

RESULTS

The serum amylase level and pancreatic weight to body weight ratio were decreased significantly in the octreotide-treated group. The serum TNF level was decreased significantly in the octreotide-treated group as compared with the control group at 6, 24, and 48 h (0.6 +/- 1.5, 2.0 +/- 3.3, and 0 vs 50 +/- 15.5, 37.5 +/- 18.4, and 13.1 +/- 12.5 U/mL, respectively). The ascites TNF level was decreased to 0 in the octreotide-treated group and was elevated in the control group at 72 h (28.0 +/- 49.0 U/mL). IL-6 production in ascites was extremely high in both groups at 6 h (80,000 +/- 43,817 pg/mL and 58,500 +/- 33,335 pg/mL), but the difference was not significant.

Alcohol and the pancreas

Alcoholic pancreatitis may be one of the most serious adverse consequences of alcohol abuse. Its diagnosis, as it has for many years, depends primarily on clinical acumen in interpreting properly the symptoms and signs of abdominal distress, buttressed by elevated pancreatic enzymes (amylase and lipase). More recently, the use of computerized tomography (CT) in selected situations has been both of confirmatory and prognostic value. Severity of abnormality by CT correlates reasonably well with a variety of clinical-laboratory clusters (APACHE system, Ranson's criteria, etc.) and aids in therapy. The pathogenesis of alcoholic pancreatitis is not fully defined. The ultimate picture is one of tissue autolysis by activated proteolytic enzymes. The triggers for such activation, however, are still not known. They are represented by three main theories: (1) large duct obstruction and/or increased permeability relative to pancreatic secretion, (2) small duct obstruction due to proteinaceous precipitates, and (3) a direct toxic-metabolic effect of ethanol on pancreatic acinar cells. While not mutually exclusive, we favor the last hypothesis as being most consistent with the effects of ethanol on other organ systems. The direct effects of ethanol and/or its metabolites may be mediated, at least in part, via oxidative stress or the generation of fatty acid ethyl esters. Autolysis (regardless of proximate mechanism(s)) leads to inflammation likely mediated via release of various cytokines. It also should be appreciated that "acute" pancreatitis (the topic of this chapter) likely represents an acute process within a chronic pancreatic exposure and injury from alcoholic abuse. The key question of why pancreatitis develops in only a small number of alcohol abusers is not resolved. Therapy depends on the severity of alcoholic pancreatitis, which is defined by clinical-laboratory and often CT criteria. Mild pancreatitis usually resolves acutely with alcohol abstention and supportive therapy. Severe pancreatitis has a significant morbidity and mortality, mainly related to the degree of pancreatic necrosis and infection. It requires meticulous combined medical-surgical care.

Experimental study of a novel phospholipase A2 inhibitor in acute pancreatitis

BACKGROUND

In acute pancreatitis, two different types of secretory phospholipase A2 (PLA2) have been found: pancreatic type I PLA2 and non-pancreatic type II PLA2. In this study a potent new PLA2 inhibitor effective against type II PLA2 was used in an experimental model of acute pancreatitis.

METHODS

In 70 rats the efficacy of the compound was analysed in two experimental models of acute pancreatitis: cerulein- and taurocholate-induced acute pancreatitis, imitating mild and severe disease respectively. Serum rat type I PLA2 protein concentration and type I and type II PLA2 catalytic activities were measured while giving the inhibitor therapeutically. In a prophylactic protocol the effect on histology was analysed.

RESULTS

In the taurocholate model, type II PLA2 activity was found to be nine-fold higher than in the cerulein model (P < 0.002), whereas the activity of type I PLA2 was not increased. The inhibitor significantly decreased serum type II PLA2 activity in the taurocholate model of acute pancreatitis (P < 0.05) but type I PLA2 protein concentration and type I PLA2 activity were not affected. The inhibitor also reduced histological tissue damage, with significant differences at 3 and 12 h (P < 0.01).

CONCLUSION

The PLA2 inhibitor significantly reduced type II PLA2 activity and was able to protect the pancreas against tissue damage. PLA2 inhibition offers the possibility of a treatment for acute pancreatitis.

Meta-analysis of somatostatin, octreotide and gabexate mesilate in the therapy of acute pancreatitis

BACKGROUND

Autodigestion of the pancreas, secondary to the activation of digestive enzymes, is the pathogenetic mechanism of acute pancreatitis (AP).

AIM

Clinical trials in which somatostatin (SS), octreotide (OCT) and gabexate mesilate (FOY) were used to treat patients with AP, were submitted to a meta-analytical evaluation. Five end-points were evaluated: early and overall mortality, patients with complications, complication rate, and patients who needed surgery.

RESULTS

In mild AP, no agent proved of value. In severe AP, both SS and OCT were beneficial in improving the overall mortality: the odds ratios (OR) were, respectively, 0.36 (95% CI: 0.20-0.64, P = 0.001) and 0.57 (95% CI: 0.35-0.88, P = 0.006). FOY had no effect on either early or overall mortality, but was effective in improving complication rate (OR = 0.70, 95% CI: 0.56-0.88, P = 0.02), number of patients with complications (OR = 0.61, 95% CI: 0.41-0.91, P = 0.01), and number of cases submitted to surgery (OR = 0.60, 95% CI: 0.39-0.92, P = 0.01). SS and OCT had no effect on these latter outcomes.

CONCLUSIONS

Antisecretory agents, such as SS and OCT, are able to reduce mortality without affecting complications, whereas antiproteases, such as FOY, have no effect on mortality but do reduce complications. A trial exploring the efficacy of combining antisecretory agents with antiproteases would be of great benefit in patients with severe AP.

Clinical update: management of acute pancreatitis

The management of acute pancreatitis commences with confirming the diagnosis and establishing the aetiology. Improved methods of assessing the biliary tree may reduce the number of patients regarded as having idiopathic pancreatitis. Detailed clinical and laboratory protocols, designed to assess severity, have no major advantage over clinical assessment. The contrast-enhanced computed tomography scan is important to assess the degree of pancreatic necrosis and to detect local complications. The treatment of pancreatitis continues to be largely supportive. However, controlled studies support the use of antibiotics in severe acute pancreatitis and indicate a possible role for the use of octreotide and antioxidants. The place of endoscopic and surgical intervention is becoming better defined. Once an attack has passed, further investigation is often required in a bid to prevent further episodes of inflammation.

Acute pancreatitis: nonsurgical management

The care of patients with severe acute pancreatitis is complex. Although numerous medical therapies have been proposed, few interventions have been shown to be of benefit in patients with severe disease. This review summarizes the nonoperative management of patients with acute pancreatitis, including therapies shown to be of little value, the role of antibiotics in patients with acute pancreatitis, the importance of monitoring and supportive care, and the rationale of endoscopic and surgical intervention.

Octreotide treatment in patients with necrotizing pancreatitis and pulmonary failure

OBJECTIVE

To determine the efficiency of intravenous infusion of octreotide in the treatment of patients with severe pancreatitis and pulmonary failure.

DESIGN

Prospective, case-control study.

SETTING

Intensive care unit of a university hospital.

PATIENTS

Treatment group: 39 patients with necrotizing pancreatitis were selected for the study. In all, pulmonary failure developed under conservative treatment and surgical intervention had been necessary because of local (abscess, necrosis) or systemic (systemic inflammatory response syndrome) complications. The outcome was prospectively followed up until death or discharge from the hospital.

CONTROL GROUP

54 case-control matched patients with acute necrotizing pancreatitis and pulmonary failure, who had not been treated with octreotide.

INTERVENTION

Each patient in the treatment group received 100 micrograms intravenous octreotide three times daily for 10 days, in addition to the standard intensive care therapy.

RESULTS

The groups (octreotide group, control group) were highly comparable with regard to age (mean age: 54, 51 years), sex, severity of illness (Acute Physiology and Chronic Health Evaluation II score: 27, 27), etiology of pancreatitis, and pretreatment at the time of admission to the intensive care unit. There was no difference in the development of renal, hepatic, gastrointestinal, hemostatic, neurologic, or local complications. But the frequency of the adult respiratory distress syndrome (18 vs 40%; p < 0.05) and circulatory shock (51 vs 87%; p < 0.05) was significantly lower in the treatment group. Furthermore, mortality was 26% (10 of 39 patients) in the octreotide group and 61% (33 of 54 patients) in the control group (p < 0.01).

CONCLUSION

The results of our case-control study showed a beneficial effect of octreotide in patients with severe necrotizing pancreatitis and pulmonary failure. Based on these data, a prospective, double-blind, placebo-controlled study should be performed to evaluate these results.

Experimental models of acute pancreatitis and their relevance to human disease

There are no experimental models which mimic the most common causes of human acute pancreatitis, i.e. gallstones and alcohol abuse. However, existing models can reproduce the morphology and physiological derangements of certain phases of the illness. Current models have been useful in elucidating the earliest events involved in the initiation and progression of pancreatitis. However, very few animal studies demonstrate effective therapeutic intervention when treatment is given after the induction of experimental pancreatitis. Since immediate intervention is unachievable in human disease, most experimental therapies have not been successfully applied to clinical disease.

Protease-antiprotease interactions and the rationale for therapeutic protease inhibitors

A number of pancreatic enzymes have been suggested as the initiating factor for acute pancreatitis. In particular, the relationship between proteases and antiproteases has been examined extensively, based on the suspicion that an imbalance between them is the central factor in the pathogenesis of acute pancreatitis. Animal studies with antiproteolytic agents in models of acute pancreatitis have shown an improvement in outcome. However, more recently, prospective, randomized, multicentre trials treating human acute pancreatitis with antiproteolytic drugs (aprotinin, gabexate mesilate, and even fresh frozen plasma) have failed to show any benefit in the clinical setting. Thus, clinically, it seems likely that antiproteolytic therapy has no effect on the course of severe acute pancreatitis. Today, the mortality in severe acute pancreatitis is determined by septic complications due to infected pancreatic necroses in the late phase 2-3 weeks after the onset of the disease. Death in the early phase of the disease has become increasingly rare where an imbalance between proteases and antiproteases may be involved.

Intrapancreatic turnover of recombinant human pancreatic secretory trypsin inhibitor in experimental porcine pancreatitis

Experimental porcine pancreatitis was induced by the injection of taurocholate into the pancreatic duct. Recombinant human pancreatic secretory trypsin inhibitor (25 mg) was administered to each animal in one of three different ways: into the pancreatic duct (n = 5), into the abdominal cavity adjacent to the pancreas (n = 2) or intravenously (n = 2). The intrapancreatic turnover was assessed during 6 h using a microdialysis technique. The intraglandular concentration, measured by enzyme-linked immunosorbent assay, was highest after injection of rhPSTI into the pancreatic duct and substantially lower after intravenous and intraperitoneal administration. The intrapancreatic half-life of the inhibitor after intraductal administration was considerably longer (3-6 times) in pigs with pancreatitis than has previously been found in the normal gland. These facts argue in favour of the intraductal administration route in future trials of antiprotease treatment in acute pancreatitis.

Experimental models of acute pancreatitis

Various models of experimental acute pancreatitis are described. An ideal model would be reproducible, have a similar natural history to that of the human disease and a similar response to treatment. Furthermore, it should be relatively cheap and simple. Few, if any, of the available experimental models completely satisfy these criteria. The appropriate choice of model is discussed, as are possible future developments in this field.

Therapy of acute pancreatitis with somatostatin

BACKGROUND

The various conservative measures which have been used to date in the treatment of acute pancreatitis have not proven helpful. However, somatostatin appears to have a favourable effect on the course and outcome of this potentially lethal disease.

METHOD AND RESULTS

Experiments in animals have shown that somatostatin prevents experimentally induced acute pancreatitis and lowers the mortality rate of established pancreatitis. In human acute pancreatitis, somatostatin reduces gastric and pancreatic secretions; it reduces the local complication rate and shortens hospitalization. The effect of somatostatin on the mortality rate of acute pancreatitis has not been demonstrated in isolated studies, although a meta-analysis of randomized controlled trials has shown a mortality rate of 6.2% in the somatostatin treated group versus 14.0% in the placebo-treated group. The synthetic analogue of somatostatin, octreotide, is an effective treatment for established local complication of acute pancreatitis, such as pancreatic fistulae and pseudocysts.

CONCLUSION

It is suggested that large-scale, carefully designed multi-centre studies of somatostatin are needed if the beneficial effects of this drug on the course and outcome of acute pancreatitis are to be evaluated.

Gabexate mesilate vs aprotinin in human acute pancreatitis (GA.ME.P.A.). A prospective, randomized, double-blind multicenter study

The authors report the results of a randomized, double-blind multicenter clinical trial on the use of gabexate mesilate vs aprotinin in the therapy of acute pancreatitis. The size of the study sample and the end points chosen for evaluation of the early systemic complications of the pancreatitis--carefully selected targets for reliable assessment of the efficacy of any protease inhibitor--lead to the conclusion that gabexate mesilate is more efficacious than aprotinin in reducing the early complications of necrotizing acute pancreatitis, if administered within 72 h of onset of symptoms. Its good tolerability means that it can be used safely even at the dose of 3 g/24 h.

Controlled trial of high-dose octreotide in treatment of acute pancreatitis. Evidence of improvement in disease severity

Nineteen consecutive patients with acute pancreatitis were sequentially allocated to treatment with high-dose octreotide (N = 9) or to act as controls (N = 10). All other aspects of treatment were similar and were according to a strict treatment protocol. There was no significant difference between the two groups on admission with regard to recognized criteria of poor prognosis. The octreotide-treated group required significantly less analgesia and after 48 hr developed significantly fewer poor prognostic indicators, including falls in hematocrit of > 10%, in serum albumin to < 32 g/liter, and in serum calcium to < 2.00 mmol/liter. Falls in arterial PO2 to < 10 kPa, in serum albumin of > 20%, and in hemoglobin of > 2 g/dl were also significantly less frequent. There was a trend towards improvement in the octreotide-treated group in every other physiological and radiological indicator of disease severity. High-dose octreotide may reduce the severity of acute pancreatitis.