Therapeutic efficacy of an antineutrophil monoclonal antibody, Urge-8, against acute necrotizing pancreatitis in rats

Central role of neutrophil in the pathogenesis of severe acute pancreatitis

Severe acute pancreatitis (SAP) is an acute abdominal disease with the strong systemic inflammatory response, and rapidly progresses from a local pancreatic damage into multiple organ dysfunction. For many decades, the contributions of neutrophils to the pathology of SAP were traditionally thought to be the chemokine and cytokine cascades that accompany inflammation. In this review, we focus mainly on those recently recognized aspects of neutrophils in SAP processes. First, emerging evidence suggests that therapeutic interventions targeting neutrophils significantly lower tissue damage and protect against the occurrence of pancreatitis. Second, trypsin activation promotes the initial neutrophils recruitment into local pancreas, and subsequently neutrophils infiltration in turn triggers trypsin production. Finally, neutrophils have the unique ability to release neutrophil extracellular traps even in the absence of pathogens.

Possible involvement of endogenous 5-HT in aggravation of cerulein-induced acute pancreatitis in mice

The aim of the present study was to elucidate the pathogenic role of endogenous 5-HT in pancreatitis. Injections of cerulein at hourly intervals caused edematous pancreatitis in mice characterized by hyperenzymemia and histological alterations. While the cerulein-induced hyperenzymemia was attenuated in mice pretreated with p-CPA, a 5-HT depletor, it was exaggerated by the preferential 5-HT2A agonist (DOI), but not by the preferential 5-HT2B agonist (BW723C86) or the preferential 5-HT2C agonist (mCPP). Selective 5-HT2A antagonists (risperidone, spiperone, ketanserin, AMI-193, and MDL 11,939) dose-dependently attenuated the hyperenzymemia; and their potency order, excepting that of ketanserin which has considerable affinity at the 5-HT2C receptor as well, paralleled their reported pKi values at the 5-HT2A receptor. Selective 5-HT2B (SB204741) and 5-HT2C (SB242084) antagonists hardly affected the hyperenzymemia. Although the non-selective 5-HT2A/2B/2C antagonists (metergoline, ritanserin, and methysergide) dose-dependently attenuated the hyperenzymemia, they were relatively less potent compared to their high pKi values at the 5-HT2A receptor. In another set of experiments, risperidone, but not SB204741 and SB242084, dose-dependently reversed the cerulein-induced histological alteration of the pancreas (inflammatory cell infiltration). These results suggest that endogenously released 5-HT activates 5-HT2A receptors to aggravate cerulein-induced pancreatitis. We propose that selective 5-HT2A antagonists may provide a new therapy for acute pancreatitis.

Treatment with BX471, a nonpeptide CCR1 antagonist, protects mice against acute pancreatitis-associated lung injury by modulating neutrophil recruitment

OBJECTIVES

Chemokines and their receptors play a key role in the pathogenesis of acute pancreatitis. BX471 is a potent nonpeptide CC chemokine receptor 1 antagonist in both human and mouse. The aim of the present study was to evaluate the effect of prophylactic and therapeutic treatment with BX471 on experimental acute pancreatitis in the mouse and to investigate the underlying mechanisms.

METHODS

Acute pancreatitis was induced in mice by hourly intraperitoneal injection of cerulein. BX471 was administered either prophylactically or therapeutically, and pancreatic inflammation and lung injury were assessed. The expression of intercellular adhesion molecule 1, P-selectin, and E-selectin was studied by reverse transcriptase-polymerase chain reaction and immunohistochemistry.

RESULTS

In cerulein-induced acute pancreatitis, treatment with BX471 significantly protected mice against lung injury associated with cerulein-induced pancreatitis by attenuating myeloperoxidase activity, an indicator of neutrophil recruitment, and lung morphological changes in histological sections. Treatment with BX471 had little effect on pancreatic damage. Blocking CC chemokine receptor 1 by BX471 also down-regulated intercellular adhesion molecule 1, P-selectin, and E-selectin expression at mRNA and protein levels in both lungs and pancreas compared with vehicle-treated groups.

CONCLUSIONS

These findings suggest that interfering with neutrophil migration and activation by targeting CC chemokine receptor 1 may represent a promising strategy to prevent disease progression in acute pancreatitis.

Chemokine receptor CCR5 deficiency exacerbates cerulein-induced acute pancreatitis in mice

Acute pancreatitis (AP) is an inflammatory disease involving the production of different cytokines and chemokines and is characterized by leukocyte infiltration. Because the chemokine receptor CCR5 and its ligands [the CC chemokines CCL3/MIP-1alpha, CCL4/MIP-1beta, and CCL5/regulated upon activation, normal T cell expressed and secreted (RANTES)] regulate leukocyte chemotaxis and activation, we investigated the expression of CCR5 ligands and the role of CCR5 and its ligands in experimental AP in mice. AP was induced by hourly intraperitoneal injections of cerulein in CCR5-deficient (CCR5(-/-)) or wild-type (WT) mice. Induction of AP by cerulein resulted in an early increase of pancreatic CCL2, CCL3, and CCL4 mRNA expression, whereas CCL5 mRNA expression occurred later. CCR5(-/-) mice developed a more severe pancreatic injury than WT mice during cerulein-induced AP, as assessed by a more pronounced increase in serum amylase and lipase levels and by more severe pancreatic edema, inflammatory infiltrates (mainly neutrophils), and necrosis. CCR5(-/-) mice also exhibited increased production of CCL2/MCP-1, CCL3/MIP-1alpha, and CCL4/MIP-1beta during the course of cerulein-induced AP. In vivo simultaneous neutralization of CC chemokines with monoclonal antibodies in CCR5(-/-) mice reduced the severity of cerulein-induced AP, indicating a role of CC chemokines in exacerbating the course of AP in the absence of CCR5. Moreover, simultaneous neutralization of CCR5 ligands in WT mice also reduced the severity of cerulein-induced AP. In conclusion, lack of the chemokine receptor CCR5 exacerbates experimental cerulein-induced AP and leads to increased levels of CC chemokines and a more pronounced pancreatic inflammatory infiltrate, suggesting that CCR5 expression can modulate severity of AP.

Treatment with bindarit, a blocker of MCP-1 synthesis, protects mice against acute pancreatitis

Chemokines are believed to play a key role in the pathogenesis of acute pancreatitis. We have earlier shown that pancreatic acinar cells produce the chemokine monocyte chemotactic protein (MCP)-1 in response to caerulein hyperstimulation, demonstrating that acinar-derived MCP-1 is an early mediator of inflammation in acute pancreatitis. Blocking chemokine production or action is a major target for pharmacological intervention in a variety of inflammatory diseases, such as acute pancreatitis. 2-Methyl-2-[[1-(phenylmethyl)-1H-indazol-3yl]methoxy]propanoic acid (bindarit) has been shown to preferentially inhibit MCP-1 production in vitro in monocytes and in vivo without affecting the production of the cytokines IL-1, IL-6, or the chemokines IL-8, protein macrophage inflammatory-1alpha, and RANTES. The present study aimed to define the role of MCP-1 in acute pancreatitis with the use of bindarit. In a model of acute pancreatitis induced by caerulein hyperstimulation, prophylactic as well as therapeutic treatment with bindarit significantly reduced MCP-1 levels in the pancreas. Also, this treatment significantly protected mice against acute pancreatitis as evident by attenuated hyperamylasemia neutrophil sequestration in the pancreas (pancreatic MPO activity), and pancreatic acinar cell injury/necrosis on histological examination of pancreas sections.

Free radical attenuation prevents thrombosis and enables photochemical inhibition of vein graft intimal hyperplasia

OBJECTIVE

Photodynamic therapy (PDT) inhibits post-interventional stenosis in balloon-injured arteries, but causes thrombosis when applied to vein grafts. This may result from added free radicals produced during the hypoxia-reperfusion injury of vein graft implantation. The purposes of this study were to determine whether a free radical scavenger could inhibit vein graft thrombosis, enabling PDT to inhibit intimal hyperplasia; and to investigate the role of neutrophils, also a source of radicals, in this setting.

METHODS

Jugular vein bypass grafts of the common carotid artery were performed in rats. PDT was administered in situ to the vein graft and artery in the presence or absence of deferoxamine (DFX), an OH- scavenger.

RESULTS

PDT alone induced thrombosis in all untreated vein grafts. DFX administration or inhibition of neutrophil adhesion to the graft prevented PDT-induced vein graft thrombosis. Moreover, DFX given together with PDT significantly decreased vein graft intimal hyperplasia (0.010 mm2 +/- 0.005 mm2; P<.002) as compared with DFX alone (0.113 mm2 +/- 0.009 mm2) or untreated control animals (0.112 +/- 0.007 mm2).

CONCLUSIONS

OH- radicals and neutrophils both have key roles in PDT-induced vein graft thrombosis. By inhibiting free radical production or neutrophil adhesion to the graft, adequate PDT can be administered for successful inhibition of vein graft intimal hyperplasia.

Treatment with Met-RANTES reduces lung injury in caerulein-induced pancreatitis

BACKGROUND

Severe acute pancreatitis leads to a systemic inflammatory response characterized by widespread leucocyte activation and, as a consequence, distant lung injury. In CC chemokines the first two cysteine residues are adjacent to each other. The aim of this study was to evaluate the effect of Met-RANTES, a CC chemokine receptor antagonist, on pancreatic inflammation and lung injury in caerulein-induced acute pancreatitis in mice.

METHODS

Acute pancreatitis was induced in mice by hourly intraperitoneal injection of caerulein. Met-RANTES was administered either 30 min before or 1 h after starting caerulein injections, and pancreatic inflammation and lung injury were assessed. There were five groups of eight mice each including controls.

RESULTS

Treatment with Met-RANTES had little effect on caerulein-induced pancreatic damage. Met-RANTES, however, reduced lung injury when given either before administration of caerulein (mean(s.e.m.) lung myeloperoxidase (MPO) 1.47(0.19) versus 3.70(0.86)-fold increase over control, P = 0.024; mean(s.e.m.) microvascular permeability 1.15(0.05) versus 3.57(0.63) lavage to plasma fluorescein isothiocyanate-labelled albumin fluorescence ratio (L/P) per cent, P = 0.002) or after caerulein administration (lung MPO 1.96(0.27) versus 3.65(0.63)-fold increase over control, P = 0.029; microvascular permeability 0.94(0.04) versus 2.85(0.34) L/P per cent, P < 0.001).

CONCLUSION

Treatment with Met-RANTES reduces lung damage associated with caerulein-induced pancreatitis in mice. Chemokine receptor antagonists may be of use for the treatment of the systemic complications of acute pancreatitis.

Expression of the chemokines MCP-1/JE and cytokine-induced neutrophil chemoattractant in early acute pancreatitis

INTRODUCTION

Inflammatory mediators play a critical role in acute pancreatitis. The precise role played by members of the chemokine family remains unclear.

AIMS

To investigate the expression of the CC chemokine monocyte chemotactic protein (MCP)-1/JE and the CXC chemokine cytokine-induced neutrophil chemoattractant (CINC) in early acute pancreatitis.

METHODOLOGY

Pancreatitis was induced in rats, either by intraperitoneal injection of cerulein or by infusion of 5% sodium taurocholate into the pancreatic duct. Expression of MCP-1/JE and CINC in pancreas and plasma was determined by immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), Northern analysis, and quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Following induction of acute pancreatitis, MCP-1/JE and CINC immunoreactivity was seen in acinar cells. Infiltrating neutrophils were strongly immunolabeled with an anti-MCP-1/JE antibody, whereas macrophages reacted strongly with an antibody to CINC. Northern analysis and quantitative real-time RT-PCR demonstrated upregulation of MCP-1/JE and CINC mRNA levels in pancreatic tissue. Plasma MCP-1 levels were significantly increased after 6 hours in the cerulein hyperstimulation model (2,444 +/- 93 microg/mL versus control, 1,853 +/- 262 microg/mL; < 0.05). Plasma CINC levels were significantly increased after 6 hours in the cerulein hyperstimulation model (1,680 +/- 134 microg/mL versus control, 725 +/- 128 microg/mL; < 0.005) and after 3 hours in the bile salt infusion model (6,663 +/- 1,405 microg/mL versus control, 2,339 +/- 800 microg/mL; < 0.05).

CONCLUSION

CINC and MCP-1/JE may be early mediators of the inflammatory response in acute pancreatitis.

Levels of the chemokines growth-related oncogene alpha and epithelial neutrophil-activating protein 78 are raised in patients with severe acute pancreatitis

BACKGROUND

Multiple organ dysfunction syndrome secondary to systemic leucocyte activation is the major cause of death following an attack of acute pancreatitis. Although plasma levels of interleukin (IL) 8 are known to be raised in acute pancreatitis, levels of other CXC chemokines such as growth-related oncogene (GRO) alpha and epithelial neutrophil-activating protein (ENA) 78, which are also potent neutrophil chemoattractants and activators, have not been measured.

METHODS

Timed plasma samples were obtained from 51 patients with acute pancreatitis, 27 with a severe attack and 24 with mild disease according to the Atlanta classification. Samples were analysed to determine levels of C-reactive protein (CRP), IL-8, GRO-alpha and ENA-78.

RESULTS

Plasma levels of IL-8, GRO-alpha and ENA-78 were increased in patients with severe as opposed to mild acute pancreatitis as early as 24 h following disease onset. Using cut-off levels of 7 pg/ml for IL-8, 70 pg/ml for GRO-alpha and 930 pg/ml for ENA-78, peak levels within the first 24 h of admission had an accuracy of 81, 71 and 87 per cent respectively in predicting the severity of an attack of acute pancreatitis.

CONCLUSION

In patients with severe acute pancreatitis plasma levels of GRO-alpha and ENA-78 were raised in addition to those of IL-8, suggesting that all three chemokines are involved in the inflammatory response in this condition.

Cerulein upregulates ICAM-1 in pancreatic acinar cells, which mediates neutrophil adhesion to these cells

Neutrophil infiltration into the pancreas is a key event in pancreatitis. Here we show that intercellular adhesion molecule-1 (ICAM-1), which regulates neutrophil adhesion, is present on rat pancreatic acinar cells, is upregulated by a hormone (cerulein) and mediates direct binding of neutrophils to acinar cells. ICAM-1 was upregulated in pancreas of rats with experimental pancreatitis induced by supramaximal doses of cerulein. Furthermore, cerulein time and dose dependently stimulated expression of ICAM-1 mRNA and protein in isolated pancreatic acinar cells. Inhibitory analysis showed that activation of transcription factor nuclear factor-kappaB (NF-kappaB) was involved in ICAM-1 upregulation by cerulein, but NF-kappaB did not mediate basal expression of ICAM-1 mRNA in acinar cells. With an adhesion assay, we found that neutrophils bind to isolated pancreatic acinar cells and that cerulein upregulates the extent of adhesion. Neutralizing ICAM-1 antibody blocked neutrophil binding to both control and cerulein-stimulated acinar cells, suggesting ICAM-1 involvement in this adhesion. Thus the acinar cell is capable of targeting neutrophils to its surface, a process that may be important for inflammatory and cell death responses in pancreatitis and other pancreatic disorders.

Does large-bowel enema reduce septic complications in acute pancreatitis?

BACKGROUND

The source of septic complications in acute pancreatitis was unknown until recent years. The pathogenesis of bacterial translocation from the gut has been accepted as the main source of pancreatic or peripancreatic infection. This study was designed to investigate the role of large bowel enema during acute pancreatitis in preventing bacterial translocation.

MATERIALS AND METHODS

Twenty-four Spraque-Dawley rats were used in this study. The rats were divided into two groups. Group I animals received biliopancreatic duct ligation plus colon cleansing by rectal enemas; group II animals received only biliopancreatic duct ligation. Rectal enemas were applied to the first group of animals three times, at 6, 24, and 48 hours after the operation using 10 cc sodium hydrogen phosphate solutions. All animals were sacrificed 72 hours later, and tissue samples were taken from mesenteric lymph nodes, pancreas, spleen, and liver for bacteriologic cultures via a midline laparatomy. Blood and cecum cultures were also prepared.

RESULTS

Positive mesenteric lymph node cultures were found in all 12 animals in group II but in only 3 of 11 animals of group I (P <0.05). Distant organ cultures were positive in 9 of group II, but the only infected distant organ culture found in group I was the positive liver culture (P <0.05).

CONCLUSION

As a result of this study, we believe that large bowel enema can reduce the frequency of septic complications in acute pancreatitis by reducing bacterial translocation.