Events In Pancreatitis Research Articles

The Acinar Cell and Early Pancreatitis Responses

Pathologic responses arising from the pancreatic acinar cell appear to have a central role in initiating acute pancreatitis. Environmental factors that sensitize the acinar cell to harmful stimuli likely have a critical role in many forms of pancreatitis, including that induced by alcohol abuse. Activation of zymogens within the acinar cell and an inhibition of secretion are critical, but poorly understood, early pancreatitis events. While there is firm evidence relating trypsinogen activation to pancreatitis, the importance of other zymogens has been less studied. Preliminary studies suggest that trypsin may be activated by mechanisms that are distinct from other zymogens. Further, unlike the small intestine, it may not catalyze the activation of other zymogens. These features could affect strategies aimed at inhibiting proteases to treat pancreatitis. Specific intracellular signals are required to activate pancreatitis pathways in the acinar cell. The most important is calcium. Recent studies have suggested that calcium release through specific calcium channels in the endoplasmic reticulum is the means by which pathological elevations in cytosolic calcium occur. Although the targets of abnormal calcium signaling are unknown, calcineurin, a calcium-dependent phosphatase, may serve such a role. Finally, recent work suggests that an acute acid load might sensitize the acinar cell to pancreatitis responses. Therapies aimed at preventing or reversing the effects of an acid load on the pancreas may be important for treatment.

Yes, Simultaneous Damage to Both the Pancreas and Liver Are Associated in Subjects Who Drink Excessive Amounts of Alcohol!

It has generally been accepted that although excessive alcohol intake might lead to liver damage or pancreatic damage, both conditions are rarely associated, and the pathogenesis of the tissue injury is not related. Indeed, many have believed that subjects with alcohol-induced liver damage are somehow not apt to develop pancreatic damage and vice versa. The study by Pace et al 1 in this issue of Clinical Gastroenterology and Hepatology refutes that remarkably well. These authors evaluated the prevalence of simultaneous liver cirrhosis and chronic pancreatitis in subjects who were heavy imbibers. Postmortem autopsy data were evaluated from 620 individuals with a history of excessive alcohol use and 100 nonalcoholic control subjects. The individuals were classified into groups on the basis of macroscopic observations of the pancreas (no injury, acute pancreatitis, fibrosis, and chronic pancreatitis) and liver (no injury, moderate steatosis, severe steatosis, and cirrhosis). The same classification system was used for histologic data that were used to confirm and correlate macroscopic findings. Of 183 subjects with liver cirrhosis, 33 (18%) had chronic pancreatitis, and 93 (51%) had pancreatic fibrosis. Of the 230 subjects with severe steatosis, 37 (16%) had chronic pancreatitis, and 97 (42%) were found to have pancreatic fibrosis. Thirtythree (39%) subjects with chronic pancreatitis also had liver cirrhosis, and 37 (44%) had severe steatosis. Thirty-eight percent of the subjects with pancreatic fibrosis were found to have liver cirrhosis, and in another 40%, severe steatosis occurred. Thirtyfive subjects demonstrated neither liver nor pancreatic damage. In the control group neither chronic pancreatitis nor cirrhosis was detected. Thus, Andrea and associates demonstrated the simultaneous occurrence of liver and pancreatic damage in these individuals who were heavy drinkers. Recent studies indicated that both chronic pancreatitis and cirrhosis have precursor lesions. Chronic pancreatitis develops through fibrosis of the pancreas. 2,3 The precursor form of liver cirrhosis appears to be hepatic steatosis. 4,5 Thus, hepatic and stellate cells are important in the development of fibrosis in both the liver and the pancreas, implying similar molecular mechanisms for the fibrotic changes in both organs. 3,6 The authors were unable to accurately evaluate the effect of nicotine use as a risk factor for liver and/or pancreatic damage because smoking data were only available for 49% of the subjects. Why is it that the consensus opinion was that these lesions in the pancreas and liver did not occur simultaneously? First, the studies in the literature that defended the nonoccurrence of these lesions were usually performed in small numbers of patients. 7 In addition, none of these studies looked systematically into morphologic changes such as pancreatic fibrosis. 8,9 Indeed, the importance of fibrosis as a crucial initial event in chronic pancreatitis has only been emphasized relatively recently. Andrea and associates readily recognized the limitations of their study such as having no quantitative data on exactly how much alcohol was taken by these “heavy drinkers” and the duration of drinking; the semiquantitative analysis of the tissue damage; the inability to evaluate nicotine use as a risk factor for either liver or pancreatic damage; and the lack of data on other potential risk factors such as diabetes, body mass index, and nutrition status. These criticisms notwithstanding, the data obtained in this large number of subjects should convincingly demonstrate, contrary to common belief, that there is a close association between pancreatic and liver injury in patients with heavy alcohol intake. The authors also make a good case for a correlation of organ damage between the pancreas and the liver.

Intracellular Trypsin Induces Pancreatic Acinar Cell Death but Not NF-κB Activation

Premature intracellular activation of the digestive enzyme trypsinogen is considered to be the initiating event in pancreatitis. However, the direct consequences of intracellular trypsin activity have not previously been examined. In the current study, a mutant trypsinogen (paired basic amino acid cleaving enzyme (PACE)-trypsinogen), which is activated intracellularly by the endogenous protease PACE, was developed. This new construct allowed for the first time direct examination of the effects of intracellular trypsin on pancreatic acinar cells. We found that PACE-trypsinogen was expressed in the secretory pathway and was activated within acinar cells. Expression of PACE-trypsinogen induced apoptosis of HEK293 cells and pancreatic acinar cells, as indicated by histology, DNA laddering, PARP cleavage, and caspase-3 activation. Cell death was blocked by the trypsin inhibitor Pefabloc but not by the pancaspase inhibitor benzyloxycarbonyl-VAD, indicating that caspase-independent pathways were also involved. However, intracellular trypsin had no significant effect on the activity of the proinflammatory transcription factor NF-kappaB. In contrast, extracellular trypsin caused cell damage and dramatically increased NF-kappaB activity. These data indicate that localization of active trypsin determines its effects on pancreatic acinar cells. This new model will greatly improve our understanding of the role of active trypsin in pancreatitis and its associated inflammatory response.

Increased Risk of Acute Pancreatitis and Biliary Disease Observed in Patients With Type 2 Diabetes

OBJECTIVEThe objective of this study was to assess the risk of acute pancreatitis in patients with type 2 diabetes compared with that in patients without diabetes. We also examined the risk of biliary disease (defined as occurrence of cholelithiasis, acute cholecystitis, or cholecystectomy), which is a major cause of pancreatitis.RESEARCH DESIGN AND METHODSWe conducted a retrospective cohort study using a large, geographically diverse U.S. health care claims database. Eligible patients (≥18 years) were enrolled for at least 12 continuous months (1999–2005), with no incident events of pancreatitis or biliary disease during that 1 year baseline period. ICD-9 codes and prescription data were used to identify patients with type 2 diabetes; ICD-9 codes were also used to identify cases of pancreatitis and biliary disease. Overall, 337,067 patients with type 2 diabetes were matched on age and sex with 337,067 patients without diabetes. Incidence rates of disease and 95% CI were calculated per 100,000 person-years of exposure.RESULTSThe type 2 diabetic cohort had a 2.83-fold (95% CI 2.61–3.06) greater risk of pancreatitis and 1.91-fold (1.84–1.99) greater risk of biliary disease compared with the nondiabetic cohort. Relative to patients of corresponding age without diabetes, younger type 2 diabetic patients had the highest risk of pancreatitis (<45 years: incidence rate ratio [IRR] 5.26 [95% CI 4.31–6.42]; ≥45 years: 2.44 [2.23–2.66]).CONCLUSIONSThese data suggest that patients with type 2 diabetes may have an increased risk of acute pancreatitis and biliary disease.

Long‐term plasma exchange for severe refractory hypertriglyceridemia: A decade of experience demonstrates safety and efficacy

Hypertriglyceridemia (hyperTG) is a common form of dyslipidemia and is frequently associated with premature coronary disease, and when severe, recurrent events of pancreatitis may occur. The management of hyperTG is generally medical (life style modification, medications). Plasma exchange (PE) has been reported to be useful in emergency situations particularly when acute pancreatitis results from extreme hyperTG. To our knowledge, there is only one report on long-term use of PE for hyperTG. We here report our results of long-term treatment of hyperTG in 6 patients with Frederickson Type V hyperlipidemia who had recurrent attacks of pancreatitis due to hyperTG refractory to medical therapy. PE was performed from one to eight times a month, mostly using a Cobe Spectra apparatus. In total, our center has performed a total of 1,593 PE sessions for hyperTG. There were no safety issues associated with PE for hyperTG other than occasional access problems (clotted fistula, IV access problems). Determination of plasma TG levels before and after PE demonstrated high efficiency of TG removal (42% to 58% reduction). There was marked clinical improvement in recurrent pancreatitis; patients had a major decrease in episodes (39% to 100%) while on regular PE, as long as they adhered to the treatment schedule. We conclude that long-term PE for hyperTG, while costly, is feasible and safe and may reduce recurrent attacks of pancreatitis.

TRANSGENIC EXPRESSION OF INTRACELLULAR ACTIVE TRYPSIN DOES NOT CAUSE ACUTE PANCREATITIS

Background: It is widely believed that premature intracellular activation of trypsinogen (TRY) is the initiating event in pancreatitis. However, its biological consequences have not yet been directly tested. Therefore, the aim was to develop a transgenic mouse model expressing intracellular active TRY. Methods: Mutant TRY, which can be activated by the endogenous protease PACE, was utilized to achieve intracellular expression and activation of trypsinogen. Using a Cre-loxP approach, mutant floxed pace-TRY mice were interbred with tamoxifen regulated Cre mice. Upon activation with tamoxifen, full-length Elastase promoter driven Cre was specifically expressed in nearly all pancreatic acinar cells. Pace-TRY expression was documented by western blot in double transgenic mice. Acinar cell morphology was monitored by light and electron microscopy. Levels of apoptosis and inflammation were examined. Results: Pace-TRY was expressed and activated in acinar cells and was correctly localized to the secretory pathway. After induction by tamoxifen, the active TRY mutant caused extensive loss of zymogen granules reaching more than 80% loss after 7d. However, despite the obvious effects on acinar cell morphology, no edema or obvious inflammation was observed and only few cells underwent apoptosis. Conclusion: These results indicate that intracellular trypsinogen activation alone does not cause acute pancreatitis. Other co-factors may be necessary to precipitate the disease. This study provides important new insights into the role of trypsin activity for the initiation of pancreatitis.

Endoscopic treatment of choledochal cyst type III

BACKGROUND: Todani type III cysts are not very common disease. Endoscopically the choledochocele is not a challenging diagnosis. Sometimes biliary stone disease is associated and events of cholangitis and pancreatitis may occur. Normally these patients are referred for surgical treatment, mainly because there is a widespread concept that choledocal cysts are very prone to develop neoplasia and must be resected. Nevertheless surgical resection is not free of morbidity. The chance for neoplasia in such cases seems to be related to the presence of pancreaticobiliary reflux towards the common bile duct. AIM: To report a case of endoscopic treatment of choledochal cyst type III with literature review. CASE REPORT: Young man with recurrent abdominal pain, fever and hyperamylasemia. An ERCP showed pancreaticobiliary maljunction and calculus impaction. Papillotomy was performed and complete biliary clearance was achieved. Amylase contents in the common bile duct was measured and normal. Due to absence of pancreatiobiliary reflux, a second endoscopic approach was performed and a wide communication between choledochocele and duodenum was done with diathermy (using the papillotome). The patient recovering was uneventful and in 30 months follow-up he remains asymptomatic. CONCLUSION: Since pancreatobiliary reflux is not present, surgical approach of the diverticulum seemed to be not necessary. Endoscopic drainage of choledococele was a good option for conservative treatment.

Abnormal crosstalk between pancreatic acini and macrophages during the clearance of apoptotic cells in chronic pancreatitis

In chronic pancreatitis (CP), both the progressive loss of acinar parenchyma and aggressive fibro-inflammatory reactions ultimately lead to irreversible organ destruction. Dying cells are normally removed by macrophages and elimination is associated with anti-inflammatory cytokine switch. We investigated whether defective clearance of damaged acini by macrophages such as compromised phagocytosis or altered cytokine reaction occurs in CP and thus represents a causative link between acinar loss and fibro-inflammation. In a checkerboard-like co-culture system, we assessed normal and CP macrophages for their phagocytic and cytokine responses to dying pancreatic acinar cells of normal or CP origin by FACS, confocal microscopy, QRT-PCR, and ELISA. In CP, phagocytosis of apoptotic acini by macrophages was not impaired; however, the associated cytokine responses were gradually perturbed. Most interestingly, only normal acini suppressed TGFbeta1 expression and accumulation specifically in normal macrophage cultures, while CP acini lost this ability. Both types of apoptotic acini induced pro-inflammatory cytokine bursts of varying strength in both types of macrophages; however, the most significant difference (more than 50-fold higher expression of IL-1beta, IL-6, and IL-8) was evident between CP/CP and normal/normal combinations, indicating that acinar and macrophage alterations synergistically lead to the ultimate CP-specific bias. In combination with in situ data comparing circulating inflammatory cells to pancreatic resident ones, our results indicate that cytokine expression in inflammatory cells undergoes spatiotemporal modulation, most likely through a successive interplay of acinar, stromal, and circulating factors. Thus, clearance of injured pancreatic acini by macrophages is associated with a unique cytokine reaction which may constitute a basis for progression of SAPE (sentinel acute pancreatitis event) to the irreversible fibro-inflammation in CP.

The changing face of the exocrine pancreas in cystic fibrosis: the correlation between pancreatic status, pancreatitis and cystic fibrosis genotype

The aims of this study were to determine the current pancreatic status of the entire cystic fibrosis (CF) population of Israel, to analyze the clinical characteristics of the pancreatic sufficient (PS) patients, and to characterize the correlation between pancreatic status, pancreatitis, and CF genotype. The Israeli CF database includes 505 patients. These patients were defined as being PS or insufficient according to their fecal pancreatic elastase level or by coefficient fat absorption findings. Mutations were categorized as severe (DeltaF508, W1282X, G542X, S549R, N1303K, Q359K/T360K, 405+1G, and 1717) or mild/variable (3849+10 kb, D1152H, G85E, I1234V, R334W, and 5T) based on disease severity in patients carrying these mutations. Age at diagnosis, presenting symptoms, sweat-chloride concentrations, occurrence of pancreatitis, presence of diabetes, and liver disease were recorded. One hundred and thirty-nine (27.5%) of the CF patients were PS. None carried two mutations associated with severe disease. Over one third (34%) had normal or borderline sweat tests; 20 of these 139 patients had pancreatitis (14.3%) but none of the 366 pancreatic insufficient patients had it. Four initially PS patients became pancreatic insufficient: conversion followed several events of pancreatitis in three of them. Nasal potential differences were all pathological in 35 tested PS patients. None had either diabetes or liver disease. A substantial number of CF patients are PS. All of them carry at least one mild mutation enabling production of a sufficient amount of normal mRNA to maintain exocrine pancreatic function. Pancreatitis occurs only in CF patients who are PS. These patients are at risk of progressing to pancreatic insufficiency.

Recurrent Acute Pancreatitis Leads to Chronic Pancreatitis: A Prospective Case Series

Purpose: Growing evidence suggests that recurrent acute pancreatitis (AP) leads to chronic pancreatitis (CP), but this sequence is seldom demonstrated in human subjects. The Sentinel Acute Pancreatitis Event (SAPE) hypothesis supports that an initial episode of AP is the first step in a complicated series of events which ultimately leads to CP. The aim of this study is to identify patients who evolved from recurrent AP (RAP) to CP. Methods: The Severity of Acute Pancreatitis Study (SAPS) database was reviewed. Patients with their first episode of AP were prospectively followed. Results: Three of 102 enrolled AP patients fulfilled the above sequence of events. All 3 patients were teenagers. Upon initial presentation, there was no evidence of CP on the CT scan performed and no clear AP etiology was identified. Patients were completely asymptomatic between recurrent attacks. All patients progressed to CP, as evidenced by CT and ERCP findings, over a relatively short period of time (Table 1). Two patients were positive for SPINK-1 mutations (N34S), and subsequently underwent total pancreatectomy with pancreatic islet autotransplantation with good results. Conclusion: The three patients presented here seem to fulfill the SAPE hypothesis. Their clinical course supports the concept that pancreatitis may be a syndrome with a broad spectrum of severity ranging from an isolated episode of AP to CP. Further studies and the development of additional disease models are needed in order to fully establish this link.Table: Patients Characteristics

Quantitative Proteomics Analysis Reveals That Proteins Differentially Expressed in Chronic Pancreatitis Are Also Frequently Involved in Pancreatic Cancer

The effective treatment of pancreatic cancer relies on the diagnosis of the disease at an early stage, a difficult challenge. One major obstacle in the development of diagnostic biomarkers of early pancreatic cancer has been the dual expression of potential biomarkers in both chronic pancreatitis and cancer. To better understand the limitations of potential protein biomarkers, we used ICAT technology and tandem mass spectrometry-based proteomics to systematically study protein expression in chronic pancreatitis. Among the 116 differentially expressed proteins identified in chronic pancreatitis, most biological processes were responses to wounding and inflammation, a finding consistent with the underlining inflammation and tissue repair associated with chronic pancreatitis. Furthermore 40% of the differentially expressed proteins identified in chronic pancreatitis have been implicated previously in pancreatic cancer, suggesting some commonality in protein expression between these two diseases. Biological network analysis further identified c-MYC as a common prominent regulatory protein in pancreatic cancer and chronic pancreatitis. Lastly five proteins were selected for validation by Western blot and immunohistochemistry. Annexin A2 and insulin-like growth factor-binding protein 2 were overexpressed in cancer but not in chronic pancreatitis, making them promising biomarker candidates for pancreatic cancer. In addition, our study validated that cathepsin D, integrin beta1, and plasminogen were overexpressed in both pancreatic cancer and chronic pancreatitis. The positive involvement of these proteins in chronic pancreatitis and pancreatic cancer will potentially lower the specificity of these proteins as biomarker candidates for pancreatic cancer. Altogether our study provides some insights into the molecular events in chronic pancreatitis that may lead to diverse strategies for diagnosis and treatment of these diseases.

Constitutive IKK2 activation in acinar cells is sufficient to induce pancreatitis in vivo

Activation of the inhibitor of NF-kappaB kinase/NF-kappaB (IKK/NF-kappaB) system and expression of proinflammatory mediators are major events in acute pancreatitis. However, the in vivo consequences of IKK activation on the onset and progression of acute pancreatitis remain unclear. Therefore, we modulated IKK activity conditionally in pancreatic acinar cells. Transgenic mice expressing the reverse tetracycline-responsive transactivator (rtTA) gene under the control of the rat elastase promoter were generated to mediate acinar cell-specific expression of IKK2 alleles. Expression of dominant-negative IKK2 ameliorated cerulein-induced pancreatitis but did not affect activation of trypsin, an initial event in experimental pancreatitis. Notably, expression of constitutively active IKK2 was sufficient to induce acute pancreatitis. This acinar cell-specific phenotype included edema, cellular infiltrates, necrosis, and elevation of serum lipase levels as well as pancreatic fibrosis. IKK2 activation caused increased expression of known NF-kappaB target genes, including mediators of the inflammatory response such as TNF-alpha and ICAM-1. Indeed, inhibition of TNF-alpha activity identified this cytokine as an important effector of IKK2-induced pancreatitis. Our data identify the IKK/NF-kappaB pathway in acinar cells as being key to the development of experimental pancreatitis and the major factor in the inflammatory response typical of this disease.

Incidence Rates of Post-ERCP Complications: A Systematic Survey of Prospective Studies

To provide health-care providers, patients, and physicians with an exhaustive assessment of prospective studies on rates of complications and fatalities associated with endoscopic retrograde cholangiopancreatography (ERCP). We searched MEDLINE (1977-2006) for prospective surveys on adult patients undergoing ERCP. "Grey literature" was sought by looking at cited references to identify further relevant studies. Data on postprocedural pancreatitis, bleeding, infections, perforations, and miscellaneous events as well as their associated fatalities were extracted independently by two reviewers. Sensitivity analysis was performed to test for data consistency between multicenter versus single center studies, and old (1977-1996) versus recent (1997-2005) reports. In 21 selected surveys, involving 16,855 patients, ERCP-attributable complications totaled 1,154 (6.85%, CI 6.46-7.24%), with 55 fatalities (0.33%, CI 0.24-0.42%). Mild-to-moderate events occurred in 872 patients (5.17%, CI 4.83-5.51%), and severe events in 282 (1.67%, CI 1.47-1.87%). Pancreatitis occurred in 585 subjects (3.47%, CI 3.19-3.75%), infections in 242 (1.44%, CI 1.26-1.62%), bleeding in 226 (1.34%, CI 1.16-1.52%), and perforations in 101 (0.60%, CI 0.48-0.72%). Cardiovascular and/or analgesia-related complications amounted to 173 (1.33%, CI 1.13-1.53%), with 9 fatalities (0.07%, CI 0.02-0.12%). As compared with old reports, morbidity rates increased significantly in most recent studies: 6.27%versus 7.51% (P(c)= 0.029). ERCP remains the endoscopic procedure that carries a high risk for morbidity and mortality. Complications continue to occur at a relatively consistent rate. The majority of events are of mild-to-moderate severity.

Pancreatobiliary Complications After Composite Visceral Transplantation: Incidence, Diagnosis and Management

Background: Combined liver-intestinal (L/SB) and multivisceral (MV) transplantation has been increasingly utilized with significant improvement in outcome. This is the first report to address the potential risk and management of pancreatobiliary (PB) complications in this unique population. Aim: Assess incidence, clinical features and management outcome of PB complications after the different types of the composite visceral graft. Methods: Between May 1990 and October 2006, a total of 227 consecutive patients received a composite visceral graft. Of these, 115 (51%) were adults and 112 (49%) were children. The composite visceral grafts were L/SB in 130 (57%) and MV in the remaining 97 (43%). The pancreas was included in 61 (53%) of the L/SB and the liver was excluded in 25 (26%) of the MV. Most donors were ABO identical and HLA matching was random with positive cross match in 23%. Immunosuppression was tacrolimus based and induction was used in 150 patients (66%). With a mean cold ischemia time of 9 ± 2 hours, UW solution was used to preserve the allograft in 82% and HTK in 18%. With ERCP being the gold standard for the diagnosis of biliary complications and pancreatic leak, significant injury of the pancreatic gland was diagnosed according to serum tests and operative findings. Results: A total of 28 PB complications were diagnosed in 20 patients with an overall incidence of 9%. Risk was similar among L/SB and MV recipients with a rate of 8% and 10%, respectively. Of the 28 morbid events, 9 were biliary complications alone, 11 were isolated pancreatic injury and 8 were combined pathology. Biliary complications included bile leak (n = 5), bile cast syndrome (n = 4), ampullary dysfunction (n = 3) and recurrent ascending cholangitis (n = 1). Pancreatic injury was necrotizing pancreatitis in 7, distal duct fistulae in 6 and chronic calcific pancreatitis in 2. ERCP was instrumental in diagnosis and treatment of cases with ampullary dysfunction, bile cast syndrome and non-surgical PB leak. However, surgical intervention was performed in patients with significant pancreatic allograft necrosis and anastomotic biliary leak. With no direct complication related mortality, all morbid events were successfully treated with the exception of a case with persistent pancreatico-cutaneous fistula. With no statistically identifiable risk factors, there was a trend toward more pancreatitis events with HTK use. Conclusions: PB complications are not uncommon after composite visceral transplantation. Early diagnosis and prompt intervention with combined surgical and endoscopic approach is essential for proper management and successful outcome.

Cause-effect relationships between zymogen activation and other early events in secretagogue-induced acute pancreatitis

We have hypothesized that the colocalization of digestive zymogens with lysosomal hydrolases, which occurs during the early stages of every experimental pancreatitis model, facilitates activation of those zymogens by lysosomal hydrolases such as cathepsin B and that this activation triggers acute pancreatitis by leading to acinar cell injury. Some, however, have argued that the colocalization phenomenon may be the result, rather than the cause, of zymogen activation during pancreatitis. To resolve this controversy and explore the causal relationships between zymogen activation and other early pancreatitis events, we induced pancreatitis in mice by repeated supramaximal secretagogue stimulation with caerulein. Some animals were pretreated with the cathepsin B inhibitor CA-074 me to inhibit cathepsin B, prevent intrapancreatic activation of digestive zymogens, and reduce the severity of pancreatitis. We show that inhibition of cathepsin B by pretreatment with CA-074 me prevents intrapancreatic zymogen activation and reduces organellar fragility, but it does not alter the caerulein-induced colocalization phenomenon or subcellular F-actin redistribution or prevent caerulein-induced activation of NF-kappaB, ERK1/2, and JNK or upregulated expression of cytochemokines. We conclude 1) that the colocalization phenomenon, F-actin redistribution, activation of proinflammatory transcription factors, and upregulated expression of cytochemokines are not the results of zymogen activation, and 2) that these early events in pancreatitis are not dependent on cathepsin B activity. In contrast, zymogen activation and increased subcellular organellar fragility during caerulein-induced pancreatitis are dependent on cathepsin B activity.

Pancreatic duct pressure, duct permeability and acute pancreatitis

The relationship between pancreatic duct pressure, duct permeability to macromolecules and the development of acute pancreatitis was studied in a cat model. Perfusion of the pancreatic duct with 15 mM glycodeoxycholic acid, ethanol administration, or secretagogue-stimulated pancreatic secretion against greater than 50 per cent duct obstruction resulted in an increase in peak pancreatic duct pressure in all animals. Duct permeability to 20,000 molecular weight dextran molecules was increased in 22 of 29 experimental animals compared with two of 22 control animals (P less than 0.01). Perfusion of the pancreatic duct with activated pancreatic enzymes resulted in acute pancreatitis in 24 of 29 experimental animals compared with three of 22 control animals (P less than 0.01). These results suggest that pancreatic ductal hypertension, resulting in increased ductal permeability to large molecules, may be a common early event in gallstone and alcoholic pancreatitis.

Extracellular Cleavage of E-Cadherin by Leukocyte Elastase During Acute Experimental Pancreatitis in Rats

Cadherins play an important role in cell-cell contact formation at adherens junctions. During the course of acute pancreatitis, adherens junctions are known to dissociate-a requirement for the interstitial accumulation of fluid and inflammatory cells-but the underlying mechanism is unknown. Acute pancreatitis was induced in rats by supramaximal cerulein infusion. The pancreas and lungs were either homogenized for protein analysis or fixed for morphology. Protein sequencing was used to identify proteolytic cleavage sites and freshly prepared acini for ex vivo studies with recombinant proteases. Results were confirmed in vivo by treating experimental pancreatitis animals with specific protease inhibitors. A 15-kilodalton smaller variant of E-cadherin was detected in the pancreas within 60 minutes of pancreatitis, was found to be the product of E-cadherin cleavage at amino acid 394 in the extracellular domain that controls cell-contact formation, and was consistent with E-cadherin cleavage by leukocyte elastase. Employing cell culture and ex vivo acini leukocyte elastase was confirmed to cleave E-cadherin at the identified position, followed by dissociation of cell contacts and the internalization of cleaved E-cadherin to the cytosol. Inhibition of leukocyte elastase in vivo prevented E-cadherin cleavage during pancreatitis and reduced leukocyte transmigration into the pancreas. These data provide evidence that polymorphonuclear leukocyte elastase is involved in, and required for, the dissociation of cell-cell contacts at adherens junctions, the extracellular cleavage of E-cadherin, and, ultimately, the transmigration of leukocytes into the epithelial tissue during the initial phase of experimental pancreatitis.

Secretin differentially sensitizes rat pancreatic acini to the effects of supramaximal stimulation with caerulein

Supramaximal stimulation of the rat pancreas with CCK, or its analog caerulein, triggers acute pancreatitis and a number of pancreatitis-associated acinar cell changes including intracellular activation of digestive enzyme zymogens and acinar cell injury. It is generally believed that some of these various acinar cell responses to supramaximal secretagogue stimulation are interrelated and interdependent. In a recent report, Lu et al. showed that secretin, by causing generation of cAMP and activation of PKA, sensitizes acinar cells to secretagogue-induced zymogen activation, and, as a result, submaximally stimulating concentrations of caerulein can, in the presence of secretin, trigger intracellular zymogen activation. We found that secretin also sensitizes acinar cells to secretagogue-induced cell injury and to subapical F-actin redistribution but that it did not alter the caerulein concentration dependence of other pancreatitis-associated changes such as the induction of a peak plateau intracellular [Ca(2+)] rise, inhibition of secretion, activation of ERK1/2, and activation of NF-kappaB. The finding that secretin sensitizes acinar cells to both intracellular zymogen activation and cell injury is consistent with the concept that these two early events in pancreatitis are closely interrelated and, possibly, interdependent. On the other hand, the finding that, in the presence of secretin, caerulein can trigger subapical F-actin redistribution without inhibiting secretion challenges the concept that disruption of the subapical F-actin web is causally related to high-dose secretagogue-induced inhibition of secretion in pancreatic acinar cells.

Chronic Alcohol Consumption Accelerates Fibrosis in Response to Cerulein-Induced Pancreatitis in Rats

Alcohol consumption is a risk factor for chronic pancreatitis (CP), but the mechanism in humans remains obscure because prolonged alcohol consumption in most humans and animal models fails to produce alcoholic chronic pancreatitis (ACP). We hypothesize that the process leading to ACP is triggered by a sentinel acute pancreatitis (AP) event; this event causes recruitment of inflammatory cells, which initiates fibrosis driven by the anti-inflammatory response to recurrent AP and/or chronic oxidative stress. The aim was to determine whether chronic alcohol consumption accelerates fibrosis in response to cerulein-induced pancreatitis in the rat. Wistar male rats were pair-fed control (C) or 5% ethanol (E) Lieber-DeCarli liquid diets. Animals were studied without pancreatitis (P0), with cerulein pancreatitis induced once (P1), or with cerulein-induced pancreatitis weekly for 3 weeks (P3). AP markers, inflammation, and fibrosis were measured histologically, by gene expression profiling and protein expression. Macrophage infiltration was reduced in EP0 versus CP0 rats, but the pattern was reversed after AP. Microabscess, severe necrosis, and early calcification were only induced in the EP3 rats. Fibrosis was significantly induced in the EP3 rats versus EP1, CP1, and CP3 by histology, hydroxyproline content, and mRNA expression for collagen alpha1(1) and procollagen alpha2(1). Proinflammatory cytokine mRNAs were up-regulated shortly after induction of AP, while the anti-inflammatory cytokines (interleukin-10 and transforming growth factor-beta) were strongly up-regulated later and in parallel with fibrogenesis, especially in the EP3 rats. Pancreatic fibrosis develops after repeated episodes of AP and is potentiated by alcohol. Expression of fibrosis-associated genes was associated with expression of anti-inflammatory cytokines in alcohol-fed rats.

Molecular and genetic mechanisms of acute and chronic pancreatitis

Hereditary pancreatitis is a rare, autosomal dominant disorder characterized by acute pancreatitis, chronic pancreatitis and a very high risk for pancreatic cancer. Over 300 families have been identified, with the majority originating in Europe. The cause of most of the cases is from mutations in the cationic trypsinogen gene, or PRSS1. The three most common mutations are R122H, N29I and R122C. The mutations are thought to cause gain-of-function mutations so that trypsinogen is either more easily activated, or active trypsin has delayed degradation. Research focused on the amino acids mutated in hereditary pancreatitis teach us about the central role of trypsin in the initiation of acute pancreatitis, and how the pancreas is normally protected from trypsin. The link between SPINK1 and trypsin activation further supports these concepts. Hereditary pancreatitis also teaches us about chronic pancreatitis. In this case, chronic pancreatitis develops in patients with recurrent acute pancreatitis. The unifying sentinel acute pancreatitis event (SAPE) model is reviewed. There are several major unanswered questions. First, how are 20% of the individuals who inherit the hereditary pancreatitis gene protected from ever getting an attack of pancreatitis? Secondly, what is the cause of the pancreatitis in the 35–40% of patients who do not have trypsinogen mutations? Third, what determines the severity of pancreatitis in those who develop pancreatitis? Finally, with knowledge of the mechanisms leading to pancreatitis, what can be done to limit or prevent damage from this disease?