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The focus of the review is on roles of autophagy and pancreatic secretory trypsin inhibitor (PSTI), an endogenous trypsin inhibitor, in trypsinogen activation in acute pancreatitis. Acute pancreatitis is a disease in which tissues in and around the pancreas are autodigested by pancreatic digestive enzymes. This reaction is triggered by the intrapancreatic activation of trypsinogen. Autophagy causes trypsinogen and cathepsin B, a trypsinogen activator, to colocalize within the autolysosomes. Consequently, if the resultant trypsin activity exceeds the inhibitory activity of PSTI, the pancreatic digestive enzymes are activated, and they cause autodigestion of the acinar cells. Thus, autophagy and PSTI play important roles in the development and suppression of acute pancreatitis, respectively.

Objectives: Although a number of pathological studies using various names/synonyms for autoimmune pancreatitis (AIP) have been reported, they do not mention the pathological staging related to origin/pathogenesis. Here, we propose a pathological staging for AIP lesions., Methods: We histopathologically examined pancreatic tissue specimens of 31 AIP patients (14 pancreatectomized and 17 needle-biopsied materials) provided by 15 hospitals in Japan and studied the relevance of clinical manifestations to the pathological stage of AIP., Results: Based on the presence or absence of acinar cells in AIP lesions, pancreatic tissue specimens were successfully divided into 20 cases in the early stage and 11 cases in the advanced stage, respectively. In the early stage, fibrosis was distributed in the interlobular and intralobular areas, admixed with acinar atrophy. Lymphoplasmacytic infiltration caused the narrowing of the ductal lumen and obliterative phlebitis. The common bile duct wall was also involved. In the advanced stage, the lesion was replaced by massive/extensive interlobular fibrosis with lymphoplasmacytic infiltrates to various degrees. Phlebitis was mild. Comparative analysis of clinical parameters between the early and advanced stages showed a significantly higher prevalence of jaundice and positive antinuclear antibodies in the early stage, and decreased serum lipase levels in the advanced stage., Conclusions: Autoimmune pancreatitis can be divided into early and advanced stages according to the presence or absence of acinar cells. Our pathological staging will facilitate understanding and evaluation of the clinical course in AIP.

Background & Aims: Serine protease inhibitor Kazal type 1 (SPINK1), which is structurally similar to epidermal growth factor, is thought to inhibit trypsin activity and to prevent pancreatitis. Point mutations in the SPINK1 gene seem to predispose humans to pancreatitis; however, the clinical significance of SPINK1 mutations remains controversial. This study aimed to elucidate the role of SPINK1., Methods: We generated Spink3-deficient (Spink3(-/-)) mice by gene targeting in mouse embryonic stem cells. Embryonic and neonatal pancreases were analyzed morphologically and molecularly. Specific probes were used to show the typical autophagy that occurs during acinar cell death., Results: In Spink3(-/-) mice, the pancreas developed normally up to 15.5 days after coitus. However, autophagic degeneration of acinar cells, but not ductal or islet cells, started from day 16.5 after coitus. Rapid onset of cell death occurred in the pancreas and duodenum within a few days after birth and resulted in death by 14.5 days after birth. There was limited inflammatory cell infiltration and no sign of apoptosis. At 7.5 days after birth, residual ductlike cells in the tubular complexes strongly expressed pancreatic duodenal homeodomain-containing protein 1, a marker of pancreatic stem cells, without any sign of acinar cell regeneration., Conclusions: The progressive disappearance of acinar cells in Spink3(-/-) mice was due to autophagic cell death and impaired regeneration. Thus, Spink3 has essential roles in the maintenance of integrity and regeneration of acinar cells.

Objectives: The pathophysiology of acute pancreatitis is strongly associated with autoactivation of trypsin. The biologic activity of trypsin on cells is attributed to the activation of protease-activated receptor-2 (PAR-2). We hypothesize that trypsin may activate acinar cells or inflammatory cells through PAR-2 signals in acute pancreatitis., Methods: We immunochemically analyzed the expression of PAR-2 in the rat acinar cell line, ARIP, and the rat pancreas, using anti-rat PAR-2 cleavage site (PCS) and anti-rat PAR-2 N-terminal fragment (PNF) antibodies. Plasma levels of PNF were determined. Furthermore, the effects of the anti-rat PCS antibody and nafamostat mesylate, a potent trypsin inhibitor, on PAR-2 activation during acute pancreatitis were also analyzed., Results: ARIP cells expressed PAR-2, which was activated by exogenous trypsin activity. We also showed that PAR-2 is strongly expressed in pancreatic acinar and duct cells and that it is activated in rat cerulein-induced acute pancreatitis. The anti-rat PCS antibody and nafamostat mesylate reduced interleukin-6 and interferon gamma production and alleviated distant organ injury., Conclusions: These results suggest that trypsin and its specific receptor, PAR-2, play an important role in cytokine production and the resultant development of distant organ injury during rat acute pancreatitis.

Acute pancreatitis is a potentially fatal disease, the severity of which ranges from a mild edematous form to a severe necrotizing form. Most patients develop systemic inflammatory response syndrome (SIRS), which is induced by proinflammatory cytokines. The cytokine production can be induced by activation of Toll-like receptor. The breakdown products of the pancreatic and peripancreatic tissues by proteases might be the agonists. Cytokines are supposed to be produced as a biological defense system. However, cytokines may often evoke organ failure and/or immunosuppressive state, if they would be produced excessively. To express this complicated pathologic condition, Ogawa proposed a concept of LISIS(local inflammation-induced systemic immunosuppression syndrome). We have to pay attention to such aspects in the management of this disease.

Context: Assessment of tissue microcirculation is one of the important aspects of pathological evaluation in acute pancreatitis. Severe ischemic change sometimes leads to the development of organ dysfunction and/or infectious complications., Objective: To evaluate the angiographic features of acute pancreatitis and correlate them with the severity of the disease., Design: Retrospective study., Patients: Twenty-seven consecutive patients with acute pancreatitis who had undergone angiography were retrospectively investigated., Main Outcome Measures: Vascular findings and Ranson score., Results: Ischemic changes were found in 18 patients (66.7%); 11 (40.7%) were severe changes. Pseudoaneurysm, bleeding, and staining were seen in 4 (14.8%), 2 (7.4%) and 5 (18.5%) patients, respectively. The rate of severe ischemic changes was significantly correlated with the Ranson score (P=0.012). Conclusions Angiographic findings are useful for the evaluation of severe acute pancreatitis.

Context: Hepatic injury is considered one of the critical complications associated with acute pancreatitis. It was proposed that initial insults to the liver in the early phase of the attack have an important priming effect, and the subsequent infectious attack (e.g. infectious pancreatic necrosis, bacterial translocation episode) constitutes a second attack on the liver., Objective: To evaluate the role of priming by induction of cerulein pancreatitis and a following second attack by endotoxemia., Main Outcome Measures: Plasma clearance and biliary excretion of indocyanine green (a hepatophillic hydrophobic organic anion)., Design: A model of acute pancreatitis in rats., Setting: Four groups of rats: untreated control, cerulein pancreatitis, endotoxemia and endotoxemia following the induction of cerulein pancreatitis (pancreatitis + endotoxemia)., Results: Biliary indocyanine green excretion was significantly disturbed only in the pancreatitis + endotoxemia group. Plasma clearance (a reflection of hepatic uptake) of indocyanine green from the blood was only slightly affected in endotoxemia group., Conclusion: Biliary secretion is quite sensitive to this hepatic injury model. Both the preceding priming insult and the following second attack are important in the development of hepatic injury.

We demonstrated dynamic aspects of granulocyte activation in rat severe acute pancreatitis, which was induced by cerulein and aggravated following lipopolysaccharide (LPS) injection. Pancreatitis induced by cerulein increased intracellular elastase activity of granulocytes in the blood. However, significant systemic cytokinemia was not provoked under such conditions. After induction of severe pancreatitis by LPS, intracellular elastase activity of circulating granulocytes decreased markedly and immediately. This decrease occurred simultaneous to induction of systemic hypercytokinemia and granulocyte migration into the lung. Overall results imply that: (1) circulating granulocytes are activated by induction of mild pancreatitis; (2) activation of granulocytes is mediated by factors other than systemic cytokinemia, such as locally produced cytokines; (3) those priming granulocytes immediately and significantly migrate from the circulation into the extravascular space by induction of endotoxemia; and (4) migration of granulocytes, in turn, may be mediated by systemic cytokinemia.

Introduction: Severe acute pancreatitis is occasionally associated with pancreatic and intestinal necrosis. Mesenteric vasoconstriction is one of the most probable types of pathogenesis of these complications., Aim: To investigate the involvement of endothelin-1 (ET-1), a potent vasoconstrictor., Methodology and Results: Plasma ET-1 concentrations were extremely high in patients with pancreatic and/or diffuse intestinal necrosis. ET-1 mRNA was demonstrated in the rat pancreas, and the production of ET-1 protein by human umbilical vein endothelial cells was enhanced by tumor necrosis factor-alpha, thrombin, and protease-activated receptor-2-activating peptide. Administration of ET-1 in vivo induced mesenteric arterial spasm and decreased pancreatic and intestinal blood flow., Conclusion: These results suggest the following: ET-1 is produced in and around the pancreas, mainly by endothelial cells, in severe acute pancreatitis; in the inflammatory setting, cytokines, activated thrombin and trypsin, may stimulate ET-1 production in a paracrine fashion; produced ET-1 may exaggerate the splanchnic microcirculation; and progressive ischemia may lead to necrosis of the pancreas and intestine.

Background: Mutations in the pancreatic secretory trypsin inhibitor ( PSTI) gene have been reported in patients suffering from chronic pancreatitis. The aim of the present study was to investigate whether similar gene mutations are present in familial and juvenile pancreatitis patients in Japan., Methods: All four exons of the PSTI gene and their flanking intronic sequences were amplified by polymerase chain reaction and sequenced for 37 familial pancreatitis patients (24 families) and 15 juvenile pancreatitis patients, distributed throughout Japan., Results: Three types of exonic mutation in the PSTI gene were observed. The N34S mutation was found in six familial pancreatitis patients (three families) and in one juvenile pancreatitis patient, and the R67C mutation was found in one familial pancreatitis patient and one juvenile pancreatitis patient. We also found a 272C>T mutation in the 3' untranslated region of exon 4 in one familial pancreatitis patient and four juvenile pancreatitis patients. It should be noted that the N34S mutation was cosegregated with two intronic mutations, specifically, IVS1-37T>C and IVS3-69insTTTT., Conclusions: The same set of N34S mutations (N34S + IVS1-37T>C + IVS3-69insTTTT) that exists in other countries was found in the PSTI gene in Japanese familial and juvenile pancreatitis patients. Another unique mutation (R67C) was also observed in two patients; 272C>T was suggested to be a normal polymorphism.

Methodology: In 1997, a cooperative nationwide survey of 192 patients diagnosed with severe acute pancreatitis in 1996 was carried out., Results: Alcoholic pancreatitis was the major etiology (46%), and the male-to-female ratio was 2.6:1. Overall, the mortality rate was 27%, which was similar to the rate (30%) in the first nationwide survey of 1,219 patients diagnosed between 1982 and 1986 that was performed in 1987. A marked difference between the surveys was the early mortality rate within 2 weeks: 52% in the 1987 survey and 29% in the current survey. We devised a new stage classification system for acute pancreatitis. Stages 0 and 1 are equivalent to mild and moderate conditions, respectively, in the conventional classification, and stages 2 and higher correspond to severe acute pancreatitis. Severity scores of 2-8 are regarded as stage 2, scores of 9-14, as stage 3, and scores of > or =15, as stage 4. The mortality rates were as follows: 0, stages 0 and 1 at hospitalization; approximately 10%, stage 2; approximately 30-40%, stage 3; and approximately 70-100%, stage 4., Conclusion: We found that stage at hospitalization reflected the prognosis of acute pancreatitis.

Background: We hypothesized that mutation of the pancreatic secretory trypsin inhibitor ( PSTI) gene may promote a predisposition to pancreatitis, possibly by reducing the inhibition of trypsin activity. Based on this hypothesis, we performed a biochemical analysis of recombinant PSTI protein., Methods: The trypsin inhibitory activity of the recombinant protein was analyzed. The activity of PSTI protein with a point mutation of the most common type: (34)Asn (AAT)-to-Ser (AGT)(101A>G N34S: N34S) in exon 3, was compared with that of the wild type., Results: The function of N34S PSTI remained unchanged under both the usual alkaline and acidic conditions compared with the wild-type PSTI. The calcium concentration did not affect the activity of recombinant PSTI. The trypsin susceptibility of the N34S protein was not increased either., Conclusions: Mechanisms other than the conformational change of PSTI associated with amino-acid substitution, such as abnormal splicing, may underlie the predisposition to pancreatitis in patients with the N34S mutation.

OBJECTIVE: The aim of this study was to examine the association of alcohol drinking and nutrient intake with chronic pancreatitis in a hospital-based case-control study. METHODS: From July, 1997, to December, 1998, 91 male patients, who were newly diagnosed as having chronic pancreatitis, were recruited as cases, and 175 controls were individually matched to each case for gender, age (± 5 yr), hospital, and time of the first visit to a hospital (± 1 yr). Information on demographic characteristics, smoking and drinking, and dietary habits were collected by a self-administered questionnaire. The strength of associations was examined by odds ratios (ORs) and 95% CIs calculated from conditional logistic regression models. RESULTS: Our study showed that the more the daily amount of alcohol drinking, the larger the OR. Men who consumed ≥ 100 g ethanol/day were at an approximately 11-fold increased risk as compared with nondrinkers. Long-term alcohol consumption (>35 yr) was associated with the increased risk (OR = 4.0). Risk of chronic pancreatitis remarkably increased with increasing cumulative alcohol consumption (trend p = 0.0001). Intakes of saturated fatty acid and vitamin E were negatively associated with the risk (trend p) = 0.05 for saturated fatty acid and 0.03 for vitamin E). CONCLUSION: Our study clearly demonstrated that prolonged heavy alcohol consumption was an important and independent risk factor, and suggested a role of lower nutrient intakes in the development of chronic pancreatitis. [ABSTRACT FROM AUTHOR]

Background/Aims: The priming mechanism of macrophages to secrete cytokines in acute pancreatitis is important for remote organ failure following septic complication. The effects of novel carboxamide derivative, IS-741, on neutrophil chemoattractant production by bronchoalveolar macrophages were studied in rats with cerulein-induced pancreatitis complicated by sepsis. Methods: Pancreatitis was induced by four intramuscular injections of cerulein (50 μg/kg at 1-hour intervals). Pancreatitis rats were injected intraperitoneally with 10 mg/kg of lipopolysaccharide (LPS) 6 h following the first cerulein injection as a septic challenge. Pancreatitis rats received a continuous intravenous injection of IS-741 (3 mg/kg/h) 30 min before the septic challenge. Results: Intense mononuclear cell infiltration and lung hemorrhage occurred in untreated pancreatitis rats complicated with sepsis, but hemorrhage was not seen in septic pancreatitis rats receiving a continuous intravenous injection of IS-741 shortly before sepsis induction. The IS-741-treated rats had lower serum concentrations of cytokine-induced neutrophil chemoattractant (CINC), as well as fewer the pulmonary neutrophils and infiltrates immunoreactive for CINC or Mac-1 (CD11b/CD18). Conclusion: The novel carboxamide derivative IS-741 reduced CINC production by bronchoalveolar macrophages and effectively prevented pancreatitis-associated lung injury following the septic challenge. [ABSTRACT FROM AUTHOR]

The proteolytic attack of the cholesterol-binding pancreatic proteinase (CBPP) on the oxidized insulin A and B chains as well as on glucagon was investigated by kinetic studies. The reaction products were isolated by high-pressure liquid chromatography and identified by amino acid analysis. The combined results reveal a pronounced selectivity of CBPP for the peptide bonds at the carboxy ends of Ala, Val, Leu, Ser, His and Thr residues with Ala, Val and Leu most favoured, indicating a close catalytic relationship to porcine pancreatic elastase [Narayanan, A. S. & Anwar, R. A. (1969) Biochem. J. 114. 11-17] and the anionic porcine pancreatic protease E [Kobayashi R., Kobayashi, Y. & Hirs, C. H. W. (1981) J. Biol. Chem. 256, 2460-2465] which resembles human pancreatic elastase 1. The immunological comparison indeed disclosed the identity of CBPP with human pancreatic elastase 1. [ABSTRACT FROM AUTHOR]

Introduction: The pancreatic secretory trypsin inhibitor (PSTI) is thought to be a specific inactivation factor of intrapancreatic trypsin activity. N34S mutation of PSTI was reported in chronic pancreatitis patients from all over the world including us, and is thought to be one of the predisposing factors for pancreatitis. The N34S mutation located close to the reactive lysine–isoleucine site (K41∼I42) might lead to a decreased inhibitory capacity. N34S is also in complete linkage with other intronic sequence variants such as IVS1-37T→C and IVS3-65insTTTT. Materials/Methods: Based on the hypothesis above, we performed biochemical experiments. (I) Activity of recombinant PSTI protein with N34S was compared to that of the wild type. (II) Molecular weight of PSTI from a patient with N34S was analysed by Western blotting to check the possibility of abnormal splicing (e.g. splice-out of exon 4). Results: (I) The function of N34S PSTI remained unchanged compared to wild-type PSTI. (II) The molecular weight of PSTI protein from a patient with N34S was not altered. Conclusion: We could not detect any functional or configurational abnormalities of N34S PSTI protein by the two experiments mentioned above. Other factors, such as translational abnormality by intronic mutation, may be associated with the predisposition to pancreatitis. [Copyright &y& Elsevier]

We demonstrated the dynamic aspects of granulocyte activation in rat severe acute pancreatitis which was induced by cerulein and aggravated following lipopolysaccharide (LPS) injection. Pancreatitis induced by cerulein increased intracellular elastase activity of granulocytes in the blood. However, significant systemic cytokinemia was not provoked under such conditions. After induction of severe pancreatitis by LPS, intracellular elastase activity of circulating granulocytes decreased markedly and immediately. The timing of this decrease was concomitant with induction of systemic hypercytokinemia and granulocytes migration into the lung. Overall results provide the following implications: (1) circulating granulocytes are activated by the induction of mild pancreatitis; (2) the activation of granulocytes is mediated by other factors than systemic cytokinemia, such as locally produced cytokine; (3) those priming granulocytes immediately and significantly migrate from the circulation into extravascular space by the induction of endotoxemia; (4) the migration of granulocytes, in turn, may be mediated by systemic cytokinemia. [Copyright &y& Elsevier]

Background: Interleukin-18 (IL-18) production is the main mechanism of hepatic injury in several animal models via further gamma interferon (IFN-γ) release. IL-18 also functions as an inducer of proinflammatory cytokines as TNF-α, which are also shown to induce organ injuries in many severe inflammatory conditions. To clarify the mechanism of hepatic injury developed in acute pancreatitis, plasma concentrations of IL-18 and its related cytokines were analyzed. Patients and methods: Plasma levels of IL-18, IL-12, IFN-γ, TNF-α, soluble TNF receptor (sTNF-R) and soluble Fas ligand (sFas-L) were measured by ELISA. Results: Plasma concentrations of IL-18 in patients with hepatic injury increased during the first few days apparently and remained so to some extent thereafter. However, IFN-γ showed no apparent increase in plasma concentrations. Those of TNF-α and sTNF-R remained increased in the hepatic injury group. Conclusion: These results suggest that IL-18 may act as a pro-inflammatory cytokine, which provokes the cytokine storm and eventually hepatic injury. [Copyright &y& Elsevier]

Pancreatic secretory trypsin inhibitor (PSTI) is a potent natural inhibitor of trypsin. We proposed a hypothesis: if the function of PSTI is impaired by its genetic mutation, trypsin may easily promote autodigestion causing pancreatitis, and performed mutational analysis of PSTI gene in patients with pancreatitis. Two exonic mutations (N34S and R67C) were suggested to be associated with the predisposition to pancreatitis. N34S mutation was co-segregated with two intronic mutations, IVS1-37T>C and IVS3-69insTTTT. Although we analyzed the function of recombinant N34S protein, we could not demonstrate the loss of function of this protein. Intronic mutations rather than N34S itself (IVS1-37T>C+N34S+IVS3-69insTTTT complex) may be associated with the decreased function of PSTI. Alternatively, increased digestion of N34S in vivo may be applicable. As for R67C, the conformational alteration of the protein by forming intramolecular or intermolecular disulfide bonds with 67Cys was strongly suggested. These results, along with the brand new findings in PSTI knockout mice, suggest that genetic mutation of PSTI is one of the important mechanisms for predisposition to pancreatitis by lowering the trypsin inhibitory function. [Copyright &y& Elsevier]

Tumor necrosis factor-α (TNF-α) is known to play a central part in the pathogenesis of acute pancreatitis. TNF-α and its two receptors (p55 and p75 TNF receptors) have shown to be expressed at various sites in the body. TNF-α is initially expressed as a 26-kDa membrane-associated perform, which is proteolytically processed to a 17-kDa secreted mature form. Recently, TNF-α converting enzyme (TACE) has been identified as a membrane-bound TNF-α activating enzyme. Hence, it is expected that the newly devised TACE inhibitor, Y39083, will be a useful candidate for the treatment of inflammatory disorders provoked by TNF-α, including acute pancreatitis. Y39083 suppressed TNF-α production in vitro and in vivo significantly. However, the production of other cytokines, such as IL-1β, IFNγ and IL-6, in vivo were not. The blockade of secreted TNF-α production by Y39083 could not improve the organ injury.These results suggest that the blockade of activities of secreted TNF-α production is not sufficient to suppress systemic cytokine reaction and distant organ injury. [Copyright &y& Elsevier]

Pancreatic secretory trypsin inhibitor (PSTI) is synthesized in the acinar cells of the pancreas and acts as a potent protease inhibitor that inhibits intrapancreatic activation of trypsin to prevent the occurrence of pancreatitis. Recently, we and other groups reported that some patients with chronic pancreatitis had a point mutation in the PSTI gene. Genetic mutations in the PSTI gene seem to promote a predisposition to pancreatitis, possibly by lowering the threshold of pancreatitis caused by other factors. In order to prove this hypothesis, we generated PSTI knockout mice using cre/mutant lox system. Heterozygous offsprings of chimeras appeared entirely normal. [Copyright &y& Elsevier]