Altered cytokine response in rat acute pancreatitis complicated with endotoxemia

Roles of Autophagy and Pancreatic Secretory Trypsin Inhibitor in Trypsinogen Activation in Acute Pancreatitis

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.

Polymorphisms of the TNF, CD14, and HSPA1B genes in patients with acute alcohol-induced pancreatitis

OBJECTIVES

Genotype assessment has been suggested to be a tool for predicting disease severity in acute pancreatitis (AP). To study this hypothesis, we performed genotype analysis of tumor necrosis factor (TNF) -308 A/G, CD14 -159C/T, and HSPA1B +1267 A/G polymorphisms.

METHODS

This is a case-control association study of 397 patients with AP (214 of whom had an alcohol-induced AP) and 300 controls. The control group comprised 218 subjects with detailed data of alcohol consumption, 70 of whom were heavy drinkers (daily alcohol intake >40 g), and 92 blood donors. The severity of AP was determined according to the Atlanta classification. Genotyping was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-assisted genotyping method.

RESULTS

Major allele frequency in TNF gene was 0.87 for patients with AP and 0.86 for controls. For CD14, the gene major allele frequency was 0.60 for patients and 0.63 for controls. For HSPA1B, the major allele frequencies were 0.52 for patients and 0.49 for controls, respectively. The allele frequencies did not differ significantly between AP patients with organ failure and those with mild disease, patients with alcohol-induced AP, or those with biliary AP. The patients with septic infectious complications (n = 47) had genotype distribution no different from those with mild, uncomplicated disease (n = 245).

CONCLUSIONS

The TNF, CD14, and HSPA1B polymorphisms studied seem not to play a role in determining the severity of AP or the risk of alcohol-induced AP and thus do not serve as a tool for predicting disease severity.

Acute pancreatitis: A complication associated with rheolytic mechanical thrombectomy of deep venous thrombosis

Percutaneous mechanical rheolytic thrombectomy is increasingly being used for the treatment of arterial, venous, and graft thromboses. We describe three cases of pancreatitis as a complication of mechanical rheolytic thrombectomy used in the treatment of caval and ileofemoral deep venous thrombosis and discuss the possible etiologic factors involved. To our knowledge, this complication has been previously reported in only two cases.

Neutrophil engagement and septic challenge in acute experimental pancreatitis in rats

AIM: To investigate the influence of neutrophil adhesion molecule blockade with monoclonal antibody (MoAb CD11b) and E. coli lipopolysaccharide (LPS) administration on experimental acute pancreatitis (AP).

METHODS: AP was induced by four ip injections of cerulein (Cn) at 1-h intervals. MoAb CD 11b and LPS were administered at the beginning of the experiment.

RESULTS: The neutrophil count and chemiluminescence were diminished at the beginning of AP. The oxidative stress parameters were found within the pancreatic gland. MoAb CD 11b used for AP resulted in a significant reduction of pancreatic infiltration and pancreatitis oxidative stress parameters. Serum interleukin-6 (IL-6) was not detected in AP animals, whereas high serum IL-6 concentration was noted only in animals receiving LPS.

CONCLUSION: Neutrophils are involved in pancreatic damage in the early stage of AP. Neutrophil infiltration reduction protects the pancreatic gland from destruction during AP. LPS does not change the early course of Cn pancreatitis in rats.

Proinflammatory role of trypsin and protease-activated receptor-2 in a rat model of acute pancreatitis

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.

The isolated perfused liver response to a 'second hit' of portal endotoxin during severe acute pancreatitis

BACKGROUND/AIM

During severe acute pancreatitis (AP), the liver may show an exaggerated response to the inflammatory products of gut injury transported in the portal vein. Our aim was to explore liver proinflammatory mediator production after a 'second hit' of portal lipopolysaccharide (LPS) during AP.

METHODS

Twenty-four rats underwent one of three 'first-hit' scenarios: (1) severe AP induced by intraductal glycodeoxycholic acid injection and intravenous caerulein infusion, (2) sham laparotomy, or (3) no first intervention. Eighteen hours later, all animals received a 'second hit' of portal LPS in an isolated liver perfusion system. Tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 concentrations were measured in portal and systemic serum, and in the perfusate 30 and 90 min after the 'second hit'. Neutrophil activation by the perfusate was assayed using dihydrorhodamine-123 fluorescence.

RESULTS

We observed a six-fold increase in IL-6 concentration across the liver during AP. All livers produced TNF-alpha after the portal LPS challenge, but this was not exaggerated by AP. No differential neutrophil activation by the perfusate was seen.

CONCLUSION

TNF-alpha, IL-1beta, IL-6 and neutrophil activator production by the isolated perfused liver, in response to a 'second hit' of portal LPS, does not appear to be enhanced during AP.

Alterations of Adhesion Molecule Expression and Inflammatory Mediators in Acute Lung Injury Induced by Septic and Non-septic Challenges

The lung is frequently the first failing organ during the sequential development of multiple organ dysfunction under both septic or non-septic conditions. The present study compared polymorphisms of tumor necrosis factor (TNFalpha), monocyte chemoattractant protein-1 (MCP-1), and adhesion molecule (AM) expression on circulating, recruited, and migrating leukocytes in the development of lung injury after induction of acute pancreatitis (AP) or abdominal sepsis by cecal ligation and puncture (CLP). Pulmonary alveolar barrier and endothelial barrier permeability dysfunction were measured. The expression of AMs (CD11b, CD11b/c, CD31, CD54 and CD62L) on leukocytes isolated from blood, lung tissue, and bronchoalveolar space were measured by flowcytometry. Plasma exudation to the interstitial tissue and the bronchoalveolar space significantly increased 1 and 3 hours after induction of pancreatitis and to the bronchoalveolar space from 6 hours after sepsis. Bronchoalveolar levels of MCP-1 significantly increased earlier than plasma exudation to the alveoli in both pancreatitis and sepsis. Alterations in expression of adhesion molecules on bronchoalveolar lavage (BAL) leukocytes can represent a marker reflecting leukocyte activation in the lung tissue, since both BAL and lung tissue leukocytes showed similar patterns of changes. Expression of adhesion molecules on circulating leukocytes increased 1 hour after induction of pancreatitis. Activating phenotypes of circulating, lung tissue and bronchoalveolar leukocytes may thus be responsible for the-development and severity of secondary lung injury.

Acute phase response in acute pancreatitis: a comparison with abdominal sepsis

BACKGROUND

Increased knowledge on the underlying pathophysiological mechanisms in acute pancreatitis (AP) and abdominal sepsis (AS) is essential, not least for the development of novel ways of treatment. The present study aims at determining dynamic changes in the systemic inflammatory response in AP and AS.

METHODS

AP was induced by the intraductal injection of sodium taurodeoxycholate in the rat, while AS was induced by caecal ligation and puncture. The animals were killed 1, 3, 6 and 9 h after challenge. Plasma exudation of radiolabelled albumin, myeloperoxidase (MPO), TNF-alpha, MCP-1, superoxide and hydrogen peroxide was measured.

RESULTS

Leakage index of human serum albumin showed a significant increase early (I h) after induction of AP and later (9h) in AS compared to controls (P < 0.05). Hydrogen peroxide generation by circulating monocytes/macrophages was high early (1 h) in AP and after 3 and 6h in AS. Superoxide generation increased by time after both challenges. MPO activity increased significantly, starting at 3 h in both AP and AS (P < 0.05). TNF-alpha increased significantly at 6 and 9 h in both models.

CONCLUSION

Our results indicate differences in the release of systemic inflammatory mediators and cellular response in AP and AS. However, potential similarities in end-effect, such as the development of remote organ injury (lungs), may exist as implied by the MPO results. Further investigations of the mechanisms are crucial.

Dynamic aspects of granulocyte activation in rat severe acute pancreatitis

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.

An experimental model of hemolysis-induced acute pancreatitis

The literature indicates that acute pancreatitis is a complication of massive hemolysis with a prevalence of about 20%. We describe an experimental model of hemolysis-induced acute pancreatitis. Hemolytic anemia was induced in rats by a single ip injection of 60 mg/kg of 20 mg/ml acetylphenylhydrazine (APH) in 20% (v/v) ethanol on the first experimental day (day 0). One hundred and fifty Wistar albino rats weighing 180-200 g were divided into three groups of 50 animals each: groups 1, 2 and 3 were injected ip with APH, 20% ethanol, and physiological saline, respectively. Ten rats from each group were sacrificed on study days 1, 2, 3, 4 and 5. Serum amylase, lipase levels and pancreatic tissue tumor necrosis factor-alpha (TNF-alpha) and platelet-activating factor (PAF) contents were determined and a histological examination of the pancreas was performed. No hemolysis or pancreatitis was observed in any of the rats in groups 2 and 3. In group 1, massive hemolysis was observed in 35 (70%) of 50 rats, moderate hemolysis in seven (14%), and no hemolysis in eight (16%). Thirty-three of 35 (94.2%) rats with massive hemolysis had hyperamylasemia, and 29 of these rats (82.8%) had histologically proven pancreatitis. The most severe pancreatitis occurred on day 3, as demonstrated by histology. Tissue TNF-alpha and PAF levels were statistically higher in group 1 than in groups 2 and 3. Acute massive hemolysis induced acute pancreatitis, as indicated by histology, in almost 80% of cases. Hemolysis may induce acute pancreatitis by triggering the release of proinflammatory and immunoregulatory cytokines.

Factors predisposing to severe acute pancreatitis: evaluation and prevention

AIM: To analyze factors predisposing to the infections associated with severe acute pancreatitis (SAP) and to work out ways for its prevention.

METHODS: Total 208 cases of SAP treated in this hospital from Jan. 1980 to Dec. 2001 were retrospectively analyzed.

RESULTS: Statistical difference in the incidence of the aforementioned infections was found between the following pairs: between the groups of bloody or non-bloody ascites, paralytic ileus lasting shorter or longer than 5 days, Ranson scores lower or higher than 5, hematocrit lower or higher than 45%, CT Balthazar scores lower or higher than 7 and between 1980.1-1992.6 or 1992.7-2001.12 admissions (χ² > 3.84, P < 0.05), while no statistical difference was established between the groups of biliogenic and non-biliogenic pancreatitis, serum amylase < 200 U/L and ≥ 200 U/L, serum calcium < 2 mmol/L and ≥ 2 mmol/L or groups of total parenteral nutrition shorter or longer than 7 days (χ² < 3.84, P > 0.05).

CONCLUSION: Occurrence of infection in patients with SAP is closely related with bloody ascites, paralytic ileus ≥ 5 days, Ranson scores ≥ 5, hematocrit ≥ 45% and CT Balthazar Scores ≥ 7, but not with pathogens, serum calcium and total parenteral nutrition (TPN). Comprehensive prevention of pancreatic infection and practice of individualized therapy contribute to reducing the incidence of infection.

A mouse model of severe acute pancreatitis induced with caerulein and lipopolysaccharide

AIM: To establish a non-traumatic, easy to induce and reproducible mouse model of severe acute pancreatitis (SAP) induced with caerulein and lipopolyasccharide (LPS).

METHODS: Thirty-two healthy mature NIH female mice were selected and divided at random into four groups (each of 8 mice), i.e., the control group (NS group), the caerulein group (Cn group), the lipopolysaccharide group (LPS group), and the caerulein+LPS group (Cn + LPS group). Mice were injected intraperitoneally with caerulein only, or LPS only, and caerulein and LPS in combination. All the animals were then killed by neck dislocation three hours after the last intraperitoneal injection. The pancreas and exo-pancreatic organs were then carefully removed for microscopic examination. And the pancreatic acinus was further observed under transmission electron microscope (TEM). Pancreatic weight, serum amylase, serum nitric oxide (NO) concentration, superoxide dismutase (SOD) and malondialdehyde (MDA) concentration of the pancreas were assayed respectively.

RESULTS: (1) NS animals displayed normal pancreatic structure both in the exocrine and endocrine. In the LPS group, the pancreas was slightly edematous, with the infiltration of a few inflammatory cells and the necrosis of the adjacent fat tissues. All the animals of the Cn group showed distinct signs of a mild edematous pancreatitis characterized by interstitial edema, infiltration of neutrophil and mononuclear cells, but without obvious parenchyma necrosis and hemorrhage. In contrast, the Cn + LPS group showed more diffuse focal areas of nonviable pancreatic and hemorrhage as well as systemic organ dysfunction. According to Schmidt’s criteria, the pancreatic histologic score showed that there existed significant difference in the Cn + LPS group in the interstitial edema, inflammatory infiltration, parenchyma necrosis and parenchyma homorrhage in comparison with those of the Cn group, LPS group and NS group (P < 0.01 or P < 0.05). (2) The ultrasturcture of acinar cells was seriously damaged in the Cn + LPS group. Chromatin margination of nuclei was present, the number and volume of vacuoles greatly increased. Zymogen granules (ZGs) were greatly decreased in number and endoplasmic reticulum exhibited whorls. The swollen mitochondria appeared, the crista of which was decreased in number or disappeared. (3) Pancreatic weight and serum amylase levels in the Cn +LPS was significantly higher than those of the NS group and the LPS group respectively (P < 0.01 or P < 0.05). However, the pancreatic wet weight and serum amylase concentration showed no significant difference between the Cn + LPS group and the Cn group. (4) NO concentration in the Cn + LPS group was significantly higher than that of NS group, LPS group and Cn group(P < 0.05 or P < 0.01). 5) The SOD and MDA concentration of the pancreas in the Cn + LPS group were significantly higher than those of NS, LPS and Cn groups (P < 0.05 or P < 0.01).

CONCLUSION: The mouse model of severe acute pancreatitis could be induced with caerulein and LPS, which could be non-traumatic and easy to induce, reproducible with the same pathological characteristics as those of SAP in human, and could be used in the research on the mechanism of human SAP.

Human leukocyte antigen-DR expression on peripheral monocytes as a predictive marker of sepsis during acute pancreatitis

INTRODUCTION

The mortality associated with severe acute pancreatitis is still high, and death in the later stage of the disease is chiefly due to bacterial infection and sepsis. However, objective parameters for the risk of sepsis in acute pancreatitis have not been established.

AIM

To investigate the value of human leukocyte antigen-DR (HLA-DR) on peripheral monocytes for predicting the development of sepsis during acute pancreatitis.

METHODOLOGY

The expression of HLA-DR on peripheral monocytes was measured in 64 patients by flow cytometry at admission and 7 and 14 days after the onset of acute pancreatitis. Twenty-eight patients with severe acute pancreatitis and 36 with mild acute pancreatitis, as determined by the Atlanta classification, were enrolled.

RESULTS

Six patients had sepsis, and two of them died during the hospital stay. At admission, the percentage of HLA-DR-expressing cells in the monocyte population was significantly lower in the patients who had sepsis in the later course than in the patients who did not have sepsis. A percentage lower than 80% at admission was observed in 17 patients, and the patients who had persistently low percentages of HLA-DR-expressing monocytes throughout the observation period had sepsis in the later clinical course, whereas the patients in whom expression recovered to the normal range were spared the development of sepsis.

CONCLUSION

In acute pancreatitis, the low percentage of HLA-DR-expressing cells in the monocyte population is a reliable predictor of the development of sepsis. Monitoring of monocyte HLA-DR expression may be a useful marker for identifying the patients who are at high risk of sepsis in acute pancreatitis.

Functional alterations of splenocytes in severe acute pancreatitis

BACKGROUND AND AIMS

Recently, the concept of "Th1 (T helper cell type 1)/Th2 (T helper cell type 2) balance" was introduced for understanding the pathophysiologic response during septic or preseptic conditions. To clarify unknown Th1/Th2 balance during acute pancreatitis, functional alterations of the splenocyte were investigated in rat experimental severe acute pancreatitis.

METHODS

Spleens were removed from rats 24 h after the induction of severe necrotizing pancreatitis by retrograde injection of 3% sodium deoxycholate. Total splenocytes were harvested and cultured in the presence or absence of concanavalin A (con A) for 24 h. Proliferative capacities and cytokine-releasing capacities were evaluated.

RESULTS

In splenocytes harvested 24 h after the induction of pancreatitis, proliferative capacity with con A stimulation was significantly lower than that of sham operation. Interleukin-2 (IL-2) release with con A stimulation and interferon-gamma release with or without con A stimulation were significantly decreased in splenocytes from the rats with pancreatitis compared with those from sham operation. Interleukin-10 (IL-10) release with con A stimulation was also significantly decreased in splenocytes from the rats with pancreatitis compared with those from sham operation. The IL-2/IL-10 concentration ratio secreted by the splenocytes from the rats with pancreatitis was significantly lower than that from those undergoing the sham operation.

CONCLUSIONS

These results suggest that splenocyte function is markedly suppressed in experimental severe acute pancreatitis and that Th1/Th2 balance tends to Th1 suppression as a whole. Dysfunction of lymphocytes including splenocytes may play a certain role in the development of subsequent septic complications in this disease.