Neutrophils, not complement, mediate the mortality of experimental hemorrhagic pancreatitis

New insights into the etiology, risk factors, and pathogenesis of pancreatitis in dogs: Potential impacts on clinical practice

While most cases of pancreatitis in dogs are thought to be idiopathic, potential risk factors are identified. In this article we provide a state‐of‐the‐art overview of suspected risk factors for pancreatitis in dogs, allowing for improved awareness and detection of potential dog‐specific risk factors, which might guide the development of disease prevention strategies. Additionally, we review important advances in our understanding of the pathophysiology of pancreatitis and potential areas for therapeutic manipulation based thereof. The outcome of pathophysiologic mechanisms and the development of clinical disease is dependent on the balance between stressors and protective mechanisms, which can be evaluated using the critical threshold theory.

The Role of Neutrophils and Neutrophil Extracellular Traps in Acute Pancreatitis

Leukocyte invasion (neutrophils and monocytes/macrophages) is closely related to the severity of acute pancreatitis (AP) and plays an important role in the systemic inflammatory response and other organ injuries secondary to AP. Increased and sustained activation of neutrophils are major determinants of pancreatic injury and inflammation. After the onset of AP, the arrival of the first wave of neutrophils occurs due to a variety of triggers and is critical for the exacerbation of inflammation. In this review, we summarize the functional characteristics of neutrophils, elastase, and heparin-binding proteins in granules, the mechanisms of neutrophil recruitment and the role of neutrophil extracellular traps (NETs) in AP.

Complement in Pancreatic Disease-Perpetrator or Savior?

The complement system is a major pillar of the humoral innate immune system. As a first line of defense against pathogens, it mediates early inflammatory response and links different branches of humoral and cellular immunity. Disorders affecting the exocrine pancreas, such as acute pancreatitis, potentially lead to a life-threatening systemic inflammatory response with aberrant activation of complement and coagulation cascades. Pancreatic proteases can activate key effectors of the complement system, which in turn drive local and systemic inflammation. Beyond that, the extent of pancreas–complement interaction covers complex pro- and anti-inflammatory mechanisms, which to this day remain to be fully elucidated. This review provides a comprehensive overview of the pathophysiological role of complement in diseases of the exocrine pancreas, based on existing experimental and clinical data. Participation of complement in acute and chronic pancreatitis is addressed, as well as its role in tumor immunology. Therapeutic strategies targeting complement in these diseases have long been proposed but have not yet arrived in the clinical setting.

Rosmarinic Acid Attenuates Sodium Taurocholate-Induced Acute Pancreatitis in Rats by Inhibiting Nuclear Factor-κB Activation

Rosmarinic Acid (RA), a caffeic acid ester, has been shown to exert anti-inflammation, anti-oxidant and antiallergic effects. Our study aimed to investigate the effect of RA in sodium taurocholate ( NaTC )-induced acute pancreatitis, both in vivo and in vitro. In vivo, RA (50 mg/kg) was administered intraperitoneally 2 h before sodium taurocholate injection. Rats were sacrificed 12 h, 24 h or 48 h after sodium taurocholate injection. Pretreatment with RA significantly ameliorated pancreas histopathological changes, decreased amylase and lipase activities in serum, lowered myeloperoxidase activity in the pancreas, reduced systematic and pancreatic interleukin-1 β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) levels, and inhibited NF-κB translocation in pancreas. In vitro, pretreating the fresh rat pancreatic acinar cells with 80 μ mol/L RA 2 h before 3750 nmol/L sodium taurocholate or 10 ng/L TNF-α administration significantly attenuated the reduction of isolated pancreatic acinar cell viability and inhibited the nuclear activation and translocation of NF-κB. Based on our findings, RA appears to attenuate damage in sodium taurocholate-induced acute pancreatitis and reduce the release of inflammatory cytokines by inhibiting the activation of NF-κB. These findings might provide a basis for investigating the therapeutic role of RA in managing acute pancreatits.

Free radicals and acute pancreatitis: much ado about … something

There is a convincing body of evidence that oxidative stress is involved in the pathogenesis of acute pancreatitis. The effects of different radical scavengers suggested that reactive oxygen metabolites are generated at very early stage of disease and contribute to amplify the pancreatic damage. Oxidative stress is also involved in the progression of the disease from a local damage to a systemic organ failure. However, therapeutic use of antioxidants failed to clearly show a clinical benefit in different trials. Therefore, although antioxidants alone seem to be not enough for the treatment of severe acute pancreatitis, future combined therapeutic strategies should include antioxidants in its composition.

Lasting inhibition of receptor-mediated calcium oscillations in pancreatic acini by neutrophil respiratory burst--a novel mechanism for secretory blockade in acute pancreatitis?

Although overwhelming evidence indicates that neutrophil infiltration is an early event in acute pancreatitis, the effect of neutrophil respiratory burst on pancreatic acini has not been investigated. In the present work, effect of fMLP-induced neutrophil respiratory burst on pancreatic acini was examined. It was found that neutrophil respiratory burst blocked calcium oscillations induced by cholecystokinin or by acetylcholine. Such lasting inhibition was dependent on the density of bursting neutrophils and could be overcome by increased agonist concentration. Inhibition of cholecystokinin stimulation was also observed in AR4-2J cells. In sharp contrast, neutrophil respiratory burst had no effect on calcium oscillations induced by phenylephrine (PE), vasopressin, or by ATP in rat hepatocytes. These data together suggest that inhibition of receptor-mediated calcium oscillations in pancreatic acini by neutrophil respiratory burst would lead to secretory blockade, which is a hallmark of acute pancreatitis. The present work has important implications for clinical treatment and management of acute pancreatitis.

Research on scutellarin parenteral solution's protective effects in rats with severe acute pancreatitis and multiple organ injuries

The aim of this study was to observe scutellarin parenteral solution's therapeutic effects and mechanisms in rats with severe acute pancreatitis (SAP). We divided SD rats into four groups randomly: (1) sham-operated group, (2) model control group, (3) scutellarin-treated group, and (4) Salvia miltiorrhiza-treated group. All of those rats in the abovementioned groups are randomly subdivided into 6 and 12 h subgroups, respectively, according to the postoperative time. Rats have been mercifully killed at different time after operation, and then detected their serum amylase, contents of ALT, AST, BUN, and Cr and observed the pathologic changes of multiple organs (pancreas, liver, kidneys, and lungs). We found that the survival rates have no marked differences (P < 0.05) between model control group and two treated groups at any time points. AST and BUN serum contents have no marked difference (P > 0.05). ALT serum contents in S. miltiorrhiza-treated group (6 and 12 h) and scutellarin-treated group (12 h) are obviously less than those in model control group (P < 0.05). The serum contents of Cr and amylase in scutellarin-treated group (6 h) are obviously less than those in model control group (P < 0.05). There is a different degree of relief on the pathologic changes of multiple organs in the two treated groups compared with those in model control group, of which pancreas and liver's pathologic severity scores in scutellarin-treated group (6 and 12 h) have reduced (P < 0.01) significantly compared with those in the model control group. However, there are no significant differences between scutellarin-treated group and S. miltiorrhiza-treated group (P > 0.05). We think the scutellarin parenteral solution has a certain protective effect on SAP rats' multiple organ injuries.

Involvement of thrombopoietin in acinar cell necrosis in L-arginine-induced acute pancreatitis in mice

Thrombopoietin (TPO) plays an important role in injuries of different tissues. However, the role of TPO in acute pancreatitis (AP) is not yet known. The aim of the study was to determine the involvement of TPO in AP. Serum TPO was assayed in necrotizing pancreatitis induced by L-arginine in mice. Recombinant TPO and anti-TPO antibody were given to mice with necrotizing pancreatitis. Amylase, lipase, lactate dehydrogenase, myeloperoxidase activity and pancreatic water content were assayed in serum and tissue samples. Pancreas and lung tissue samples were also collected for histological evaluation. Immunohistochemistry of amylase α and PCNA were applied for the study of acinar regeneration and TUNEL assay for the detection of apoptosis in the pancreas. Increased levels of serum TPO were found in necrotizing pancreatitis. After TPO administration, more severe acinar necrosis was found and blockade of TPO reduced the acinar necrosis in this AP model. Acinar regeneration and apoptosis in the pancreas were affected by TPO and antibody treatment in necrotizing pancreatitis. The severity of pancreatitis-associated lung injury was worsened after TPO treatment, but attenuated after Anti-TPO antibody treatment. In conclusion, serum TPO is up-regulated in the necrotizing pancreatitis induced by L-arginine in mice and may be a risk factor for the pancreatic acinar necrosis in AP. As a pro-necrotic factor, blockade of TPO can attenuate the acinar necrosis in AP and may be a possible therapeutic intervention for AP.

Role of neutrophils in the activation of trypsinogen in severe acute pancreatitis

The relationship between inflammation and proteolytic activation in pancreatitis is an unresolved issue in pancreatology. The purpose of this study was to define the influence of neutrophils on trypsinogen activation in severe AP. Pancreatitis was induced by infusion of taurocholate into the pancreatic duct in C57BL/6 mice. For neutrophil depletion, an anti-Gr-1 antibody was administered before pancreatitis induction. Administration of the anti-Gr-1 antibody reduced circulating neutrophils by 97%. Pancreatic TAP and serum amylase levels increased 2 h and 24 h after induction of pancreatitis. Neutrophil depletion reduced pancreatic TAP and serum amylase levels at 24 h but not at 2 h after pancreatitis induction. Pancreatic MPO and infiltration of neutrophils, as well as MIP-2 levels, were increased 24 h after taurocholate infusion. Two hours after taurocholate administration, no significant pancreatic infiltration of neutrophils was observed. Injection of the anti-Gr-1 antibody abolished MPO activity, neutrophil accumulation, and MIP-2 levels, as well as acinar cell necrosis, hemorrhage, and edema in the pancreas at 24 h. Moreover, taurocholate-provoked tissue damage and MPO activity in the lung were normalized by neutrophil depletion. Intravital fluorescence microscopy revealed a 97% reduction of leukocytes in the pancreatic microcirculation after administration of the anti-Gr-1 antibody. Our data demonstrate that initial trypsinogen activation is independent of neutrophils, whereas later activation is dependent on neutrophils in the pancreas. Neutrophils are critical in mediating pancreatic and lung tissue damage in severe AP.

Rho-kinase signalling regulates trypsinogen activation and tissue damage in severe acute pancreatitis

BACKGROUND AND PURPOSE

Severe acute pancreatitis (SAP) is characterized by trypsinogen activation, infiltration of leucocytes and tissue necrosis but the intracellular signalling mechanisms regulating organ injury in the pancreas remain elusive. Rho-kinase is a potent regulator of specific cellular processes effecting several pro-inflammatory activities. Herein, we examined the role of Rho-kinase signalling in acute pancreatitis.

EXPERIMENTAL APPROACH

Pancreatitis was induced by infusion of taurocholate into the pancreatic duct in C57BL/6 mice. Animals were treated with a Rho-kinase inhibitor Y-27632 (0.5-5 mg·kg⁻¹) before induction of pancreatitis.

KEY RESULTS

Taurocholate infusion caused a clear-cut increase in blood amylase, pancreatic neutrophil infiltration, acinar cell necrosis and oedema formation in the pancreas. Levels of pancreatic myeloperoxidase (MPO), macrophage inflammatory protein-2 (MIP-2), trypsinogen activation peptide (TAP) and lung MPO were significantly increased, indicating local and systemic disease. Inhibition of Rho-kinase activity dose-dependently protected against pancreatitis. For example, 5 mg·kg⁻¹ Y-27632 reduced acinar cell necrosis, leucocyte infiltration and pancreatic oedema by 90%, 89% and 58%, respectively, as well as tissue levels of MPO by 75% and MIP-2 by 84%. Moreover, Rho-kinase inhibition decreased lung MPO by 75% and blood amylase by 83%. Pancreatitis-induced TAP levels were reduced by 61% in Y-27632-treated mice. Inhibition of Rho-kinase abolished secretagogue-induced activation of trypsinogen in pancreatic acinar cells in vitro.

CONCLUSIONS AND IMPLICATIONS

Our novel data suggest that Rho-kinase signalling plays an important role in acute pancreatitis by regulating trypsinogen activation and subsequent CXC chemokine formation, neutrophil infiltration and tissue injury. Thus, these results indicate that Rho-kinase may constitute a novel target in the management of SAP.

Prophylactic glycine administration attenuates pancreatic damage and inflammation in experimental acute pancreatitis

BACKGROUND/AIMS

Acute pancreatitis (AP) is characterized by premature zymogen activation, systemic inflammatory response resulting in inflammatory infiltrates, sustained intracellular calcium, neurogenic inflammation and pain. The inhibitory neurotransmitter and cytoprotective amino acid glycine exerts a direct inhibitory effect on inflammatory cells, inhibits calcium influx and neuronal activation and therefore represents a putative therapeutic agent in AP.

METHODS

To explore the impact of glycine, mild AP was induced in rats by supramaximal cerulein stimulation (10 μg/kg BW/h) and severe AP by retrograde injection of sodium taurocholate solution (3%) into the common biliopancreatic duct. 100/300 mmol glycine was administered intravenously before induction of AP. To elucidate the effect of glycine on AP, we determined pathomorphology, pancreatic cytokines as well as proteases, serum lipase and amylase, pancreatic and lung MPO activity and pain sensation.

RESULTS

Glycine administration resulted in a noticeable improvement of pathomorphological alterations in AP, such as a reduction of necrosis, inflammatory infiltrates and cytoplasmic vacuoles in cerulein pancreatitis. In taurocholate pancreatitis, glycine additionally diminished pancreatic cytokines and MPO activity, as well as serum lipase and amylase levels.

CONCLUSIONS

Glycine reduced the severity of mild and much more of severe AP by attenuating the intrapancreatic and systemic inflammatory response. Therefore, glycine seems to be a promising tool for prophylactic treatment of AP. and IAP.

Role of macrophages in the progression of acute pancreatitis

In addition to pancreatic cells, other inflammatory cell populations contribute to the generation of inflammatory mediators during acute pancreatitis. In particular, macrophages could be activated by mediators released during pancreatitis by a damaged pancreas. It has been reported that peritoneal macrophages, alveolar macrophages and Kupffer cells become activated in different stages of severe acute pancreatitis. However, macrophages display remarkable plasticity and can change their physiology in response to environmental cues. Depending on their microenvironmental stimulation, macrophages could follow different activation pathways resulting in marked phenotypic heterogeneity. This ability has made these cells interesting therapeutical targets and several approaches have been assayed to modulate the progression of inflammatory response secondary to acute pancreatitis. However, despite the recent advances in the modulation of macrophage function in vivo, the therapeutical applications of these strategies require a better understanding of the regulation of gene expression in these cells.

Role of platelets in experimental acute pancreatitis

BACKGROUND

Platelets not only control thrombosis and haemostasis but may also regulate inflammatory processes. Acute pancreatitis (AP) is characterized by changes in both coagulation and proinflammatory activities. The role of platelets in AP is not yet known.

METHODS

AP was induced in C57BL/6 mice by repeated caerulein administration (50 µg/kg intraperitoneally). Mice received a platelet-depleting or control antibody before caerulein challenge. Neutrophil infiltration, myeloperoxidase (MPO) and macrophage inflammatory protein (MIP) 2 levels, acinar cell necrosis and haemorrhage in the pancreas, as well as serum amylase activity, were determined 24 h after caerulein injection. In an alternative model of pancreatitis, L-arginine (4 g/kg intraperitoneally) was given twice with an interval of 1 h and tissue samples were taken after 72 h [Correction added after online publication 29 September 2010: in the preceding sentence, 4 mg/kg was corrected to 4 g/kg].

RESULTS

Caerulein administration increased acinar cell necrosis, neutrophil infiltration, focal haemorrhage and serum amylase levels. Platelet depletion reduced acinar cell necrosis, haemorrhage and serum amylase levels in AP. Depletion of platelets decreased caerulein-induced MPO levels and neutrophil recruitment in the pancreas. Platelet depletion abolished caerulein-induced MIP-2 generation in the pancreas and circulation. The effects of platelet depletion on necrosis, neutrophils and MPO levels were confirmed in L-arginine-induced pancreatitis.

CONCLUSION

Platelets play a crucial role in AP by regulating neutrophil infiltration, most likely mediated by MIP-2 production in the pancreas.

Effect of dexamethasone on peripheral blood leukocyte immune response in bile-pancreatic duct obstruction-induced acute pancreatitis

Our aim was to analyze the effects of dexamethasone (Dx) (1mg/kg), prophylactically or therapeutically administered, on the inflammatory response triggered by peripheral blood leukocytes during acute pancreatitis (AP) induced in rats by bile-pancreatic duct obstruction (BPDO) and their consequences in the progress of the disease. Flow cytometry was used to analyze the distribution of the major leukocyte populations, the CD45 expression and the activated state of monocytes as reflected by the membrane-bound intercellular adhesion molecule-1 (ICAM-1) and the production of tumor necrosis factor-alpha (TNF-alpha) and monocyte chemoattract protein-1 (MCP-1) in response to lipopolysaccaride (LPS). Interleukin-6 (IL-6) plasma levels, pancreatic fluid content and histology of pancreas sections were also evaluated. Dx, given either before or after AP, blunted the monocyte increase induced by BPDO-induced AP, but did not change lymphocyte and neutrophil counts. Membrane-bound ICAM-1 expression did not vary in circulating monocytes during BPDO, either in Dx-treated or non-treated rats. Both Dx treatments inhibited TNF-alpha and MCP-1 production in non-stimulated and LPS-stimulated monocytes, whose response was found to be higher than in controls from early AP. Leukocyte CD45 expression was found to be reduced in rats with AP and shifted to control values in Dx-post-treated rats. Cytokinemia as well as pancreatic edema and leukocyte infiltration found in BPDO rats were reduced by Dx given either before or after AP. We conclude that prophylactic and therapeutic Dx treatments inhibited the inflammatory response triggered by circulating leukocytes in rats with BPDO-induced AP, thus contributing to reducing the severity of the disease.

Hydrogen sulfide promotes transient receptor potential vanilloid 1-mediated neurogenic inflammation in polymicrobial sepsis

OBJECTIVE

To investigate the interaction and involvement of hydrogen sulfide and transient receptor potential vanilloid type 1 in the pathogenesis of sepsis. Hydrogen sulfide has been demonstrated to be involved in many inflammatory states including sepsis. Its contribution in neurogenic inflammation has been suggested in normal airways and urinary bladder. However, whether endogenous hydrogen sulfide would induce transient receptor potential vanilloid type 1-mediated neurogenic inflammation in sepsis remains unknown.

DESIGN

Prospective, experimental study.

SETTING

Research laboratory.

SUBJECT

Male Swiss mice.

INTERVENTIONS

Mice were subjected to cecal ligation and puncture-induced sepsis and treated with transient receptor potential vanilloid type 1 antagonist capsazepine (15 mg/kg subcutaneous) 30 mins before cecal ligation and puncture. To investigate hydrogen sulfide-mediated neurogenic inflammation in sepsis, DL-propargylglycine (50 mg/kg intraperitoneal), an inhibitor of hydrogen sulfide formation was administrated 1 hr before or 1 hr after the induction of sepsis, whereas sodium hydrosulfide (10 mg/kg intraperitoneal), a hydrogen sulfide donor, was given at the same time as cecal ligation and puncture. Lung and liver myeloperoxidase activities, liver cystathionine-gamma-lyase activity, plasma hydrogen sulfide level, histopathological examination, and survival studies were determined after induction of sepsis.

MEASUREMENTS AND MAIN RESULTS

Capsazepine treatment attenuates significantly systemic inflammation and multiple organ damage caused by sepsis, and protects against sepsis-induced mortality. Similarly, administration of sodium hydrosulfide exacerbates but capsazepine reverses these deleterious effects. In the presence of DL-propargylglycine, capsazepine causes no significant changes to the attenuation of sepsis-associated systemic inflammation, multiple organ damage, and mortality. In addition, capsazepine has no effect on endogenous generation of hydrogen sulfide, suggesting that hydrogen sulfide is located upstream of transient receptor potential vanilloid type 1 activation, and may play a critical role in regulating the production and release of sensory neuropeptides in sepsis.

CONCLUSIONS

The present study shows that hydrogen sulfide induces systemic inflammation and multiple organ damage characteristic of sepsis via transient receptor potential vanilloid type 1-mediated neurogenic inflammation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Differing Roles of the Classical and Mannose-Binding Lectin Complement Pathways in the Events following Skeletal Muscle Ischemia-Reperfusion

Complement is an important mediator of the injuries observed after skeletal muscle ischemia and subsequent reperfusion. Although the classical pathway had been assumed to be the major pathway of activation leading to injury, the mannose-binding lectin (MBL) pathway might also play a contributing role. In this study, we found that MBL-deficient mice had significant protection after skeletal muscle reperfusion injury compared with wild-type, classical pathway-specific C1q-deficient mice, or MBL-deficient mice reconstituted with recombinant human MBL. MBL-deficient mice, however, were not protected from permeability edema or secondary lung injury after ischemia-reperfusion. These data indicate that blockade of the classical pathway alone (C1q) is protective against permeability edema and remote pulmonary injury but not protective against histologic muscle injury. In contrast, blocking the MBL pathway alone protects against histological injury but is not protective against permeability edema or lung injury. Thus, the activation of both pathways is likely responsible for the full spectrum of injuries observed after skeletal muscle reperfusion injury.

Interaction of complement and leukocytes in severe acute pancreatitis: potential for therapeutic intervention

In acute pancreatitis, local as well as systemic organ complications are mediated by the activation of various inflammatory cascades. The role of complement in this setting is unclear. The aim of the present study was to determine the level of complement activation in experimental pancreatitis, to evaluate the interaction of complement and leukocyte-endothelium activation, and to assess the effects of complement inhibition by soluble complement receptor 1 (sCR1) in this setting. Necrotizing pancreatitis was induced in Wistar rats by the combination of intravenous cerulein and retrograde infusion of glycodeoxycholic acid into the biliopancreatic duct; edematous pancreatitis was induced by intravenous cerulein only. In control animals, a sham operation (midline laparotomy) was performed. Complement activation, leukocyte sequestration, and pancreatic as well as pulmonary injury were assessed in the presence/absence of sCR1. Increased levels of C3a were found in necrotizing but not in edematous pancreatitis. When complement activation in necrotizing pancreatitis was blocked by sCR1, levels of C3a and total hemolytic activity (CH50) were decreased. Leukocyte-endothelial interaction, as assessed by intravital microscopy, and pancreatic as well as pulmonary organ injury (wet-to-dry weight ratio, MPO activity, and histology) were ameliorated by sCR1. As a result of the present study, necrotizing but not edematous pancreatitis is characterized by significant and early complement activation. Based on the interaction of complement and leukocytes, complement inhibition by sCR1 may be a valuable option in the treatment of leukocyte-associated organ injury in severe pancreatitis.

Effect of early continuous high-volume hemofiltration on histopathological changes of pancreas and extrapancreatic organs in pigs with severe acute pancreatitis

AIM: To observe the effect of early continuous high-volume hemofiltration on the histopatho-logical changes of pancreas and extrapancreatic organs in pigs with severe acute pancreatitis (SAP).

METHODS: Twenty-four domestic pigs were randomly and averagely assigned into 3 groups: control group (untreated model group) as group A, low-volume hemofiltration [20 mL/(kg·h)] group as group B, and high-volume hemofiltration [100 mL/(kg·h)] group as group C. SAP model was produced by injection of sodium taurocholate (40 g/L, 1 mL/kg) and trypsin (2 U/kg) via the pancreatic duct. The pigs in group B and C received hemofiltration immediately after modeling. The parameters including survival time and histopathological scores of pancreas and extra-pancreatic organs were observed.

RESULTS: The median survival times were 41, 50 and 65 h in group A, B, and C, respectively, and there were significant differences among them (P < 0.01). The histopathological scores had no marked differences between the three groups (P > 0.05). However, the scores for hepatocellular degeneration, pulmonary hyaline membranes and microthrombi, and renal tubular damage were obviously lower than those in the other groups (P < 0.05).

CONCLUSION: Although hemofiltration can not reduce the pancreatic damage in pigs with SAP, early continuous high-volume hemofiltration can significantly ameliorate the hepatocellular degeneration, the formation of pulmonary hyaline membranes and microthrombi, and the renal tubular damage in pigs with SAP, which is useful in improving the survival time.

Effects of immunosuppressive and immunostimulative treatment on pancreatic injury and mortality in severe acute experimental pancreatitis

OBJECTIVES

Acute pancreatitis is associated with substantial alterations of the immunologic host response which has been claimed to promote remote organ dysfunction, septic complications, and mortality. Treatment with immunomodulating substances has been subject of few experimental studies with still conflicting results.

METHODS

We used the taurocholate-induced model of severe acute pancreatitis (SAP) in rats which were assigned to different treatment regimen: isotonic saline (SAP-S) for nontreated controls, recombinant rat interferon-gamma for immunostimulation (SAP-IFN-gamma), and FK506 for immunosuppression (SAP-FK506). Animals were killed after 3, 6, and 24 hours as well as 3 and 7 days, and parameters of local and systemic severity were assessed.

RESULTS

Treatment with IFN-gamma and FK506 attenuated the progression of intrapancreatic necrosis within the first 24 hours after pancreatitis induction along with a substantial reduction of subsequent neutrophil tissue infiltration as shown by decreased myeloperoxidase activity. Enhanced cell death by apoptosis during the postacute course was reduced in FK506-treated animals only. Pancreatic interleukin (IL) 1beta messenger RNA up-regulation occurred early and was slightly suppressed in both treatment groups; tumor necrosis factor alpha (TNF-alpha) and IL-2 messenger RNA expression paralleled the onset of apoptosis and was markedly decreased in IFN-gamma- and FK506-treated rats. The 2 therapeutic regimens had similar effects on intrapancreatic and systemic IL-1beta and TNF-alpha protein release; however, the profiles of both cytokines were differently influenced. Whereas IFN-gamma and FK506 treatment lead to an enhanced intrapancreatic and systemic TNF-alpha protein release during the early course, IL-1beta concentrations were significantly reduced within the late intervals. Seven-day mortality was 44% in saline-, 29% in IFN-gamma-, and 25% in FK506-treated rats (P = not significant).

CONCLUSIONS

Severe acute pancreatitis is associated with early alterations of the immune response comprising overt T-cell activation and impaired monocyte/macrophage function alike. Targeting either immunologic derangement improves local pancreatic damage and systemic severity. However, because mortality was not improved, a therapeutic benefit of immunomodulating substances in clinical SAP remains to be defined.

Role of phosphatidylinositol 3-kinase/protein kinase B signal transduction pathway in activation of neutrophils during severe acute pancreatitis

AIM: To investigate the role of phosphatidy-linositol 3-kinase/protein kinase B (PI3K/PKB) signal transduction pathway in the activation of neutrophils during severe acute pancreatitis (SAP).

METHODS: Thirty male health adult Sprague Dawley rats were averagely randomized into group A, B and C. SAP model was established in group B and C by retrograde injection of 50 g/L sodium taurocholate into the pancreatic and biliary duct. The rats in group C were treated with wortmannin 4 h before modeling, and those in group A served as the controls. All the rats were killed 6 h after modeling, and the neutrophils were isolated by density gradient centrifugation. The serum levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were analyzed by enzyme-linked immunosorbent assay (ELISA). The expression of TNF-α and IL-1β mRNA were detected by RT-PCR and the activity of phosphorylated PKB (p-PKB) was examined by Western blot.

RESULTS: The serum levels of TNF-α and IL-1β were significantly higher in group B than those in group A (150.8 ± 31.7 ng/L vs22.4 ± 5.2 ng/L, P < 0.01; 217.5 ± 38.4 ng/L vs 43.7 ± 9.6 ng/L, P < 0.01), and mRNA levels of TNF-α and IL-1β were also markedly increased (0.72 ± 0.06 vs 0.19 ± 0.03, P < 0.01; 0.84 ± 0.11 vs 0.14 ± 0.04, P < 0.01). However, the serum and mRNA levels of TNF-α and IL-1β were all significantly decreased in group C in comparison with those in group B (TNF-α: 70.9 ± 11.3 ng/L, 0.32 ± 0.04; IL-1β: 93.0 ± 11.5 ng/L, 0.22 ± 0.04; all P < 0.01). Western blot showed that the activity of p-PKB was increased in group B as compared with that in group A (0.63 ± 0.08 vs 0.34 ± 0.03, P < 0.01), but it was markedly down-regulated in group C (0.38 ± 0.06, P < 0.01).

CONCLUSION: PI3K/PKB signal transduction pathway is activated in the neutrophils during severe acute pancreatitis, which mediates the production of pro-inflammatory cytokines TNF-α and IL-1β.

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Neutrophils in development of multiple organ failure in sepsis

Multiple organ failure is a major threat to the survival of patients with sepsis and systemic inflammation. In the UK and in the USA, mortality rates are currently comparable with and projected to exceed those from myocardial infarction. The immune system combats microbial infections but, in severe sepsis, its untoward activity seems to contribute to organ dysfunction. In this Review we propose that an inappropriate activation and positioning of neutrophils within the microvasculature contributes to the pathological manifestations of multiple organ failure. We further suggest that targeting neutrophils and their interactions with blood vessel walls could be a worthwhile therapeutic strategy for sepsis.

Mechanism of lung injury and protective effect of prostaglandin E1 in experimental acute pancreatitis

AIM: To explore the mechanism of lung injury in experimental acute pancreatitis (AP) and the protective effect of prostaglandin E₁ (PGE₁).

METHODS: Seventy-eight rats were averagely and randomly divided into sham operation, AP, and PGE₁ group. AP model was induced by creating a closed duod enal loop in rats. The rats in PGE₁ group were intravenously injected with PGE₁ (60 ng/kg). The histopathological changes of pancreatic and pulmonary tissues were examined by microscopy. The serum level of amylase, the activity of myeloperoxidase (MPO), the pulmonary level of lipid peroxidation (LPO), and lung capillary permeability (LCP) were measured. The expression of pulmonary intercellular adhesion molecule-1 (ICAM-1) was determined by immunohistochemical technique (ABC).

RESULTS: In AP group, the progressive pathological damages in the pancreas and lung tissues were clearly observed. The activity of pulmonary MPO (12 h: 5.65 ± 0.80 vs 1.22 ± 0.71 kat/g, P < 0.01; 24 h: 7.22 ± 1.05 vs 1.48 ± 0.57 kat/g, P < 0.01), the level of LPO (12 h: 1.44 ± 0.63 vs 0.38 ± 0.07 μmol/g, P < 0.01; 24 h: 3.64 ± 0.83 vs 0.44 ± 0.15 μmol/g, P < 0.01) and LCP (12 h: 145.4 ± 23.0 vs 47.3 ± 5.5 μg/g wet weight, P < 0.01), as well as pulmonary ICAM-1 expression were markedly increased as compared with those in sham operation group. In comparison with those in AP group, the activity of MPO (12 h: 2.96 ± 1.04 vs 5.65 ± 0.80 kat/g, P < 0.05; 24 h: 3.68 ± 1.15 vs 7.22 ± 1.05 kat/g, P < 0.05) and the level of LPO (12 h: 0.86 ± 0.34 vs 1.44 ± 0.63 μmol/g, P < 0.05; 24 h: 1.69 ± 0.45 vs 3.64 ± 0.83 μmol/g, P < 0.05) in the lung tissues were significantly decreased, and the level of LCP (12 h: 105.9 ± 23.9 vs 145.4 ± 23.0 μg/g wet weight, P < 0.05), as well as pulmonary ICAM-1 expression was down-regulated (12 h: P < 0.05; 24 h: P < 0.01) in PGE1 group. Pathological examination revealed that intra-alveolar hemorrhage, edema and polymorphonuclear leukocytes (PMN) infiltration in the lung tissues were attenuated after PGE₁ treatment, although pancreatic damages were not alleviated.

CONCLUSION: The over-expression of ICAM-1, PMN infiltration and the release of free oxygen radicals in lung tissues may be closely related to pancreatitis-associated lung injury. PGE₁ can ameliorate lung injury by reducing ICAM-1 expression and inhibiting PMN activation and the release of free oxygen radicals.

Microcirculation disturbance affects rats with acute severe pancreatitis following lung injury

AIM: To study the effects of microcirculation disturbance (MD) on rats with acute severe pancreatitis (ASP).

METHODS: We developed ASP rat models, and anatomized separately after 1, 3, 5, 7, and 9 h. We took out blood and did hemorrheologic examination and erythrocyte osmotic fragility test, checked up the water content, capillary permeability, and genetic expression of intercellular adhesion molecule-1 (ICAM-1) in lung tissues, examined the apoptosis degree of blood vessel endothelium while we tested related gene expression of Bax and Bcl-2 in lung tissues. We did the same examination in control group.

RESULTS: The viscosity of total blood and plasma, the hematocrit, and the erythrocyte osmotic fragility were all increased. Fibrinogen was decreased. The water content in lung tissues and capillary permeability were increased. Apoptosis degree of blood vessel endothelium was increased too. ICAM-1 genetic expression moved up after 1 h and reached its peak value after 9 h.

CONCLUSION: MD plays an important role in ASP following acute lung injury (ALI). The functional damage of blood vessel endothelium, the apoptosis of capillary vessel endothelium, WBC edging-concentration and the increasing of erythrocyte fragility are the main reasons of ALI.

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.

From acinar cell damage to systemic inflammatory response: current concepts in pancreatitis

Acute pancreatitis represents a local inflammatory disorder with severe systemic consequences. Significant progress in understanding the pathophysiology of acute pancreatitis has been achieved in recent years. However, there is no clear concept about initialization and propagation of the disease both in experimental models and in humans. Furthermore, reliable strategies to evaluate prognosis and perform therapy are still missing. The review focuses on mechanisms originating from acinar cells leading to a systemic inflammatory response in experimental pancreatitis.