Chemotactic peptide uptake in acute pancreatitis: correlation with tissue accumulation of leukocytes

Stimulation of Central α2 Receptors Attenuates Experimental Necrotizing Pancreatitis

OBJECTIVES

Severe necrotizing pancreatitis (SNP) is a disease with relevant morbidity and mortality until today. No specific therapy is in sight. Central α2 agonists such as clonidine and dexmedetomidine are known to have anti-inflammatory effects though the cholinergic anti-inflammatory pathway and are implemented in the clinical routine as adjunct sedative drugs. Their potential effect on SNP has not yet been tested.

METHODS

Severe necrotizing pancreatitis was induced in male Wistar rats. Four treatment groups received either clonidine or dexmedetomidine before (prophylactic) or after induction of SNP (therapeutic). After 12 hours, pancreatic morphologic injury, systemic proinflammatory high-mobility group box 1 protein, and pancreatic and pulmonary myeloperoxidase levels were evaluated.

RESULTS

Severe necrotizing pancreatitis was fully established 12 hours after induction. "Prophylactic" and "therapeutic" administration of clonidine and dexmedetomidine reduced pancreatic morphologic injury (P < 0.05 vs SNP), serum proinflammatory high-mobility group box 1 protein (P < 0.0001 vs SNP), as well as pancreatic and pulmonary myeloperoxidase levels (P < 0.01 vs SNP).

CONCLUSIONS

Prophylactic and therapeutic applications of the central α2 agonists clonidine and dexmedetomidine are effective to attenuate local and systemic injury in experimental SNP and should be evaluated in the clinical setting.

Obestatin Accelerates the Recovery in the Course of Ischemia/Reperfusion-Induced Acute Pancreatitis in Rats

Objective

Several previous studies have shown that obestatin exhibits protective and regenerative effects in some organs including the stomach, kidney, and the brain. In the pancreas, pretreatment with obestatin inhibits the development of cerulein-induced acute pancreatitis, and promotes survival of pancreatic beta cells and human islets. However, no studies investigated the effect of obestatin administration following the onset of experimental acute pancreatitis.

Aim

The aim of this study was to evaluate the impact of obestatin therapy in the course of ischemia/reperfusion-induced pancreatitis. Moreover, we tested the influence of ischemia/reperfusion-induced acute pancreatitis and administration of obestatin on daily food intake and pancreatic exocrine secretion.

Methods

Acute pancreatitis was induced by pancreatic ischemia followed by reperfusion of the pancreas. Obestatin (8nmol/kg/dose) was administered intraperitoneally twice a day, starting 24 hours after the beginning of reperfusion. The effect of obestatin in the course of necrotizing pancreatitis was assessed between 2 and 14 days, and included histological, functional, and biochemical analyses. Secretory studies were performed on the third day after sham-operation or induction of acute pancreatitis in conscious rats equipped with chronic pancreatic fistula.

Results

Treatment with obestatin ameliorated morphological signs of pancreatic damage including edema, vacuolization of acinar cells, hemorrhages, acinar necrosis, and leukocyte infiltration of the gland, and led to earlier pancreatic regeneration. Structural changes were accompanied by biochemical and functional improvements manifested by accelerated normalization of interleukin-1β level and activity of myeloperoxidase and lipase, attenuation of the decrease in pancreatic DNA synthesis, and by an improvement of pancreatic blood flow. Induction of acute pancreatitis by pancreatic ischemia followed by reperfusion significantly decreased daily food intake and pancreatic exocrine secretion. Administration of obestatin at doses used was without significant effect with regard to daily food intake or pancreatic exocrine secretion in sham-operated rats, as well as in rats with acute pancreatitis. On the other hand, obestatin abolished a statistical significance of difference in food intake between animals with AP and control animals without pancreatic fistula and induction of AP.

Conclusion

Treatment with the exogenous obestatin reduces severity of ischemia/reperfusion-induced acute pancreatitis and accelerates recovery in this disease. The involved mechanisms are likely to be multifactorial, and are mediated, at least in part, by anti-inflammatory properties of obestatin.

Pretreatment with obestatin reduces the severity of ischemia/reperfusion-induced acute pancreatitis in rats

Obestatin, as ghrelin, has been originally extracted from the stomach, which remains its major source. Previous studies have shown that administration of obestatin exhibits protective and healing-promoting effects in several organs, including the stomach and kidney. In pancreas, pretreatment with obestatin inhibits the development of cerulein-induced acute pancreatitis and promotes survival of pancreatic beta cells and human islets. The aim of the present study was to check the universality of protective effect of obestatin in the pancreas. For this reason we investigated the influence of obestatin administration on the development of ischemia/reperfusion-induced pancreatitis. Acute pancreatitis was induced by pancreatic ischemia followed by reperfusion of the gland. Obestatin (4, 8 or 16 nmol/kg/dose) was administered intraperitoneally twice: 0.5h before exposure to ischemia, and 3h after the first injection. The effect of obestatin on the course of necrotizing pancreatitis was assessed after 6-h reperfusion, and included histological, functional, and biochemical analyses. Treatment with obestatin reduced morphological signs of pancreatic damage including edema, vacuolization of acinar cells, hemorrhages, acinar necrosis, and leukocyte infiltration of the gland. These effects were accompanied by an improvement of pancreatic DNA synthesis and superoxide dismutase activity, and a decrease in serum level of lipase and pro-inflammatory interleukin-1β. Moreover pretreatment with obestatin reduced myeloperoxidase activity and malondialdehyde concentration in pancreatic tissue of rats with acute pancreatitis.

CONCLUSIONS

Administration of obestatin inhibits the development of ischemia/reperfusion-induced acute pancreatitis. This observation, taken together with previous findings that obestatin protects the pancreas against cerulein-induced pancreatitis, indicates that protective effect of obestatin in the pancreas is universal and independent of the primary cause of acute pancreatitis.

Inflammatory profiling of early experimental necrotizing pancreatitis

AIMS

Inflammatory mediators play a pivotal role in severe necrotizing pancreatitis (SNP). Therapeutic approaches aim at the early inflammatory liberation of cytokines to avoid systemic complications. The present study evaluates the kinetics of inflammatory mediator release in SNP.

MAIN METHODS

Experimental SNP was induced in male Wistar rats using the GDOC model. The animals were allocated into seven groups (n = 6/group). In group 1, sample harvesting was performed after sham operation while in groups 2-7 this was performed 1 h, 2 h, 4 h, 6 h, 9 h, and 12 h after initiation of SNP, respectively. Inflammatory mediator release,morphologic injury, and tissue MPO concentrations were evaluated between 1 and 12 h after induction.

KEY FINDINGS

Pancreatic injury showed a continuous increase over the observation period (p b 0.05, respectively). MPO levels in the pancreas and lungs increased until 12 h after induction (p b 0.05, respectively). Antiinflammatory IL-10 showed an early peak and the pro-inflammatory mediators TNFα and IL-1β peaked after 6 and 9 h, respectively (p b 0.05, respectively). HMGB1 levels constantly increased over time (p b 0.05, respectively).

SIGNIFICANCE

The present study shows the release of relevant pro- and anti-inflammatory mediators in SNP for the first time in one single experimental setup. Inflammatory mediators peak within the first few hours after SNP induction. Consequently, the effect of therapeutic approaches on early changes in cytokine release should be evaluated later than 2 h after initiation.

Pharmacological cholinergic stimulation as a therapeutic tool in experimental necrotizing pancreatitis

OBJECTIVES

The endogenous immune response is influenced by the stimulation of the vagal nerve. Stimulation or ablation has a direct impact on the release of pro- and anti-inflammatory mediators. In the progression of acute pancreatitis from local to systemic disease, these mediators play a pivotal role. This study evaluates the effect of pharmacologic stimulation of the cholinergic system on pancreatic damage in experimental necrotizing pancreatitis.

METHODS

Experimental severe necrotizing pancreatitis was induced in male Wistar rats using the glycodeoxycholic acid model. Animals with acute pancreatitis (n = 6) were compared with animals with acute pancreatitis and prophylactic or therapeutic pharmacologic activation of the cholinergic system using nicotine, physostigmine, or neostigmine (n = 36). Twelve hours after the induction of acute pancreatitis, morphological damage as well as the myeloperoxidase levels of the pancreas and the serum levels of high-mobility group box 1 protein were evaluated.

RESULTS

Prophylactic and delayed therapeutic application of nicotine, physostigmine, or neostigmine significantly attenuated the severity of acute pancreatitis 12 hours after the induction of severe necrotizing pancreatitis compared with untreated controls as evaluated with histological scores, myeloperoxidase, and high-mobility group box 1 levels (P < 0.05).

CONCLUSIONS

Stimulation of the cholinergic system is useful to attenuate damage in experimental acute pancreatitis. Not only prophylactic but also delayed application was effective in the present study.

Alcohol pretreatment increases hepatic and pulmonary injury in experimental pancreatitis

BACKGROUND

Systemic complications including pancreatitis-associated lung injury (PALI) are critical factors that determine the outcome of severe necrotizing pancreatitis (SNP). The aim of the present study was to evaluate the role of chronic alcohol exposure on the development of PALI.

METHODS

48 rats were fed either a Lieber deCarli control or alcohol diet for 6 weeks. After completion, SNP was induced by intraductal infusion of bile salt followed by intravenous infusion of cerulein over 6 h. Control animals received i.v. Ringer's solution. Intravital microscopy of the liver was performed 6 h after induction of SNP to evaluate hepatic perfusion and leukocyte adhesion. Serum parameters, edema, inflammation, and histological changes were evaluated at 12 h. IL-6 levels were evaluated in portal venous and systemic blood as well as in pancreatic tissue homogenates.

RESULTS

Alcohol pretreatment did not affect pancreatic injury in SNP. PALI was aggravated after alcohol ingestion. These animals showed increased hepatic microcirculatory disturbances, compared to SNP alone. IL-6 showed peak levels in SNP with alcohol pretreatment, although they were also elevated in SNP alone. Systemic levels of IL-6 were higher than in the portal vein.

CONCLUSION

In SNP, alcoholic pretreatment increases pulmonary damage, while pancreatic injury is identical. The liver seems to participate in this effect by increased hepatic cytokine release.

Dual, time-dependent deleterious and protective effect of anandamide on the course of cerulein-induced acute pancreatitis. Role of sensory nerves

Some recent studies indicate that cannabis may induce acute pancreatitis in humans and administration of anandamide increases the severity of acute pancreatitis; whereas another study exhibits some therapeutic effects in acute pancreatitis. Aim of the present study was to discover what is the reason for these opposite confusing results and to determine the role of sensory nerves in this effect. Acute pancreatitis was induced in rats by cerulein. Anandamide, an endogenous cannabinoid, was administered i.p. (1.5 micromol/kg) before or 2 h after cerulein administration. Stimulation of sensory nerves was performed by capsaicin (0.5 mg/kg s.c.). In rats treated with combination of anandamide plus capsaicin, capsaicin was given 10 min after each dose of anandamide. After the last injection of cerulein or 4 h later, the study was terminated. In our study we observed that stimulation of sensory nerves by capsaicin, before administration of cerulein, reduced the severity of acute pancreatitis. Anandamide, administered alone before cerulein, increased pancreatic damage in acute pancreatitis. Anandamide administered in combination with capsaicin, before cerulein, abolished the capsaicin-induced protective effect on the pancreas. Opposite effects were observed when capsaicin and anandamide were administered after injection of cerulein. Capsaicin increased the severity of acute pancreatitis, whereas anandamide reduced pancreatic damage and reversed the deleterious effect of capsaicin. We conclude that the effect of anandamide on the severity of acute pancreatitis depends on the phase of this disease. Administration of anandamide, before induction of pancreatitis, aggravates pancreatic damage; whereas anandamide administered after induction of pancreatitis, reduces the severity of acute pancreatitis. Sensory nerves are involved in the mechanism of this biphasic effect of anandamide.

Pharmacologic cholinesterase inhibition improves survival in experimental sepsis

OBJECTIVE

Lethal sepsis occurs when an excessive inflammatory response evolves that cannot be controlled by physiologic anti-inflammatory mechanisms, such as the recently described cholinergic anti-inflammatory pathway. Here we studied whether the cholinergic anti-inflammatory pathway can be activated by pharmacologic cholinesterase inhibition in vivo.

DESIGN

Prospective, randomized laboratory investigation that used an established murine sepsis model.

SETTING

Research laboratory in a university hospital.

SUBJECTS

Female C57BL/6 mice.

INTERVENTIONS

Sepsis in mice was induced by cecal ligation and puncture. Animals were treated immediately with intraperitoneal injections of nicotine (400 microg/kg), physostigmine (80 microg/kg), neostigmine (80 microg/kg), or solvent three times daily for 3 days.

MEASUREMENTS AND MAIN RESULTS

Treatment with physostigmine significantly reduced lethality (p < or = .01) as efficiently as direct stimulation of the cholinergic anti-inflammatory pathway with nicotine (p < or = .05). Administration of cholinesterase inhibitors significantly down-regulated the binding activity of nuclear factor-kappaB (p < or = .05) and significantly reduced the concentration of circulating proinflammatory cytokines tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 (p < or = .001), and pulmonary neutrophil invasion (p < or = .05). Animals treated with the peripheral cholinesterase inhibitor neostigmine showed no difference compared with physostigmine-treated animals.

CONCLUSIONS

Our results demonstrate that cholinesterase inhibitors can be used successfully in the treatment of sepsis in a murine model and may be of interest for clinical use.

Cancer risk among the relatives of patients with pancreatic ductal adenocarcinoma

BACKGROUND/AIMS

Pancreatic cancer is a leading cause of cancer-related death; the most consistently identified risk factors are smoking and family history. Our aims were to examine familial aggregations of pancreas and other cancers, and to determine the relative risk of the family members.

METHODS

We prospectively collected data on the families of patients presenting with pancreatic ductal adenocarcinoma. Smoking habits and alcohol consumption of the probands were compared with the available statistics on the Italian population. Mortality from cancer was investigated in first-degree relatives, and age-dependent risks of dying from pancreatic cancer and other tumors were compared with background population levels.

RESULTS

Data for 570 families were collected, including 9,204 relatives. Probands were 3- to 5-fold more often heavy smokers than the general population, and 9.3% of them reported a positive family history of pancreatic cancer. In first-degree relatives, only mortality from pancreatic cancer was significantly increased (relative risk at age 85 years = 2.7). Lifetime risk of dying of pancreas cancer was 4.1% for the relatives of all probands, and was 7.2% for the relatives of probands who developed disease before 60 years of age.

CONCLUSIONS

The data suggest that genetic susceptibility to pancreatic cancer may be attributable, in addition to BRCA2, to moderate- to low-penetrance gene(s).

Pancreatic cellular injury after cardiac surgery with cardiopulmonary bypass: frequency, time course and risk factors

Although often clinically silent, pancreatic cellular injury (PCI) is relatively frequent after cardiac surgery with cardiopulmonary bypass; and its etiology and time course are largely unknown. We defined PCI as the simultaneous presence of abnormal values of pancreatic isoamylase and immunoreactive trypsin (IRT). The frequency and time evolution of PCI were assessed in this condition using assays for specific exocrine pancreatic enzymes. Correlations with inflammatory markers were searched for preoperative risk factors. One hundred ninety-three patients submitted to cardiac surgery were enrolled prospectively. Blood IRT, amylase, pancreatic isoamylase, lipase, and markers of inflammation (alpha1-protease inhibitor, alpha2-macroglobulin, myeloperoxidase) were measured preoperatively and postoperatively until day 8. The postoperative increase in plasma levels of pancreatic enzymes and urinary IRT was biphasic in all patients: early after surgery and later (from day 4 to 8 after surgery). One hundred thirty-three patients (69%) experienced PCI, with mean IRT, isoamylase, and alpha1-protease inhibitor values higher for each sample than that in patients without PCI. By multiple regression analysis, we found preoperative values of plasma IRT >or=40 ng/mL, amylase >or=42 IU/mL, and pancreatic isoamylase >or=20 IU/L associated with a higher incidence of postsurgery PCI (P < 0.005). In the PCI patients, a significant correlation was found between the 4 pancreatic enzymes and urinary IRT, total calcium, myeloperoxidase, alpha1-protease inhibitor, and alpha2-macroglobulin. These data support a high prevalence of postoperative PCI after cardiac surgery with cardiopulmonary bypass, typically biphasic and clinically silent, especially when pancreatic enzymes were elevated preoperatively.

Enterokinase induces severe necrosis and rapid mortality in cerulein pancreatitis: Characterization of a novel noninvasive rat model of necro-hemorrhagic pancreatitis

BACKGROUND

Unlike edematous pancreatitis, induction of severe necrotizing pancreatitis in rats generally requires an invasive laparotomy with infusion and/or ligation of the pancreatic duct or duodenal or arterial occlusion. The aim of this study was to establish and characterize a noninvasive model of severe acute pancreatitis in rats.

METHODS

Wistar rats were infused intravenously with cerulein or a combination of cerulein and enterokinase. Saline (154-mmol/L NaCl) or enterokinase only was infused in controls. In a first set of experiments, intrapancreatic protease activation and the release of cytokines were correlated with the severity of organ injury. Pancreatic and pulmonary injuries were determined at 6 h. In a second set of experiments, we assessed 24-h survival, serum parameters possibly reflecting the course of the disease, and morphologic changes later in the course of the disease.

RESULTS

The severity of pancreatic injury and survival were correlated strongly with the amount of enterokinase infused simultaneously with cerulein. Trypsin as well as elastase and cathepsin B activity in pancreatic tissue samples were increased markedly in these animals. Marked pancreatic hemorrhage, necrosis, and leukocyte infiltration were present in animals with the greatest amounts of enterokinase infused. IL-6 and LDH, but not IL-1beta, CRP, and amylase, in serum correlated with the severity of pancreatitis.

CONCLUSIONS

This noninvasive rat model of acute pancreatitis is characterized by major pancreatic necrosis, hemorrhage, and fatality. The simple and noninvasive induction technique may have advantages for future studies on inflammatory changes and sepsis in necrotizing pancreatitis compared with other currently available invasive models.

Extracellular cleavage of E-cadherin by leukocyte elastase during acute experimental pancreatitis in rats

BACKGROUND & AIMS

Cadherins play an important role in cell-cell contact formation at adherens junctions. During the course of acute pancreatitis, adherens junctions are known to dissociate-a requirement for the interstitial accumulation of fluid and inflammatory cells-but the underlying mechanism is unknown.

METHODS

Acute pancreatitis was induced in rats by supramaximal cerulein infusion. The pancreas and lungs were either homogenized for protein analysis or fixed for morphology. Protein sequencing was used to identify proteolytic cleavage sites and freshly prepared acini for ex vivo studies with recombinant proteases. Results were confirmed in vivo by treating experimental pancreatitis animals with specific protease inhibitors.

RESULTS

A 15-kilodalton smaller variant of E-cadherin was detected in the pancreas within 60 minutes of pancreatitis, was found to be the product of E-cadherin cleavage at amino acid 394 in the extracellular domain that controls cell-contact formation, and was consistent with E-cadherin cleavage by leukocyte elastase. Employing cell culture and ex vivo acini leukocyte elastase was confirmed to cleave E-cadherin at the identified position, followed by dissociation of cell contacts and the internalization of cleaved E-cadherin to the cytosol. Inhibition of leukocyte elastase in vivo prevented E-cadherin cleavage during pancreatitis and reduced leukocyte transmigration into the pancreas.

CONCLUSIONS

These data provide evidence that polymorphonuclear leukocyte elastase is involved in, and required for, the dissociation of cell-cell contacts at adherens junctions, the extracellular cleavage of E-cadherin, and, ultimately, the transmigration of leukocytes into the epithelial tissue during the initial phase of experimental pancreatitis.

99mTc-hexamethylpropylene amineoxime leukocyte scintigraphy in acute pancreatitis: an alternative to contrast-enhanced computed tomography?

OBJECTIVE

Contrast-enhanced computed tomography (CECT) is the most efficient imaging technique for the diagnosis and staging of acute pancreatitis (AP); its use, however, may be unfeasible in some patients as a consequence of the drawbacks of intravenous (IV) contrast material. The aim of this study was to test the utility of labeled leukocyte scintigraphy (LLS) as an alternative imaging technique to CECT for the staging of AP.

METHODS

Sixty-six patients with AP were prospectively studied. All patients underwent CECT and pancreatic LLS using (99m)Tc-hexamethylpropylene amineoxime as leukocyte label within a time interval of 2 days, in the early phase of AP. In addition, all patients had their serum C-reactive protein (CRP) concentration measured within 48-72 h after admission. CECT images were analyzed for Balthazar's grade of pancreatitis and for the presence or absence of pancreatic necrosis. Scintigraphic activity of 3-4 h planar images was scored on a 0-2 scale in relation to physiological liver uptake.

RESULTS

LLS score was significantly related (p < 0.001) to both components of CECT (grade of pancreatitis and pancreatic necrosis). LLS and serum CRP showed similar results for detecting the most severe pancreatic damage as showed by their respective receiver operating characteristic (ROC) curves. Sensitivities and specificities of LLS score of 2 were, respectively, 62% and 96% for the detection of grade D-E pancreatitis and 90% and 89% for the detection of pancreatic necrosis. Scintigraphic score of 2 increased the likelihood of grade D-E pancreatitis from 32% (pretest probability) to 87% (posttest probability) (likelihood ratio: 13.9) and that of pancreatic necrosis from 16% to 60% (likelihood ratio: 8.4).

CONCLUSIONS

Our results show that leukocytes are related to the severity of local pancreatic damage in AP. Thus, LLS is a potential alternative technique to CECT for staging AP.

Clinical molecular imaging

This review summarizes the rapidly growing field of molecular imaging, the spatially localized and/or temporally resolved sensing of molecular and cellular processes in vivo. Molecular imaging is used to map the anatomic locations of specific molecules of interest within living tissue and has enormous potential as a powerful means to diagnose and monitor disease. Molecular imaging agents comprise a targeting component that confers localization and a component that enables external detectability with an imaging modality, such as PET, SPECT, MRI, optical, and ultrasound. The advantages and disadvantages of each of these modalities are discussed in regard to spatial resolution, temporal resolution, sensitivity, and cost. Molecular imaging agents can be divided into three categories, Type A, which bind directly to a target molecule, Type B, which are accumulated by molecular or cellular activity by the target, and Type C, which are undetectable when injected but can be imaged after they are activated by the target. The current status of clinical molecular imaging agents is presented as well as examples of some preclinical applications. The value of molecular imaging is illustrated by some examples for diseases such as cancer, neurological and psychiatric disorders, cardiovascular disease, infection and inflammation, and the monitoring of gene therapy and stem cell therapy.

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.

Neutrophil metabolic activity but not neutrophil sequestration reflects the development of pancreatitis-associated lung injury

OBJECTIVE

Activated neutrophils are presumed to injure pulmonary endothelium by releasing oxygen radicals, proteases, and proinflammatory cytokines. Standard counting methods do not distinguish between leukocytosis, neutrophil sequestration, and activation. We used leukocyte uptake of the glucose analog [18F]fluorodeoxyglucose (18FDG), which indicates postmigrational neutrophil activity, to identify and quantify the relationship between acute respiratory distress syndrome and neutrophil activation in experimental pancreatitis in rats.

DESIGN

Prospective, experimental study.

SETTING

Research laboratory at a university hospital.

SUBJECTS

Mild and severe pancreatitis models in the rat. INTERVENTIONS Pulmonary (with muscle as control) leukocyte accumulation was assessed by uptake of technetium-99m-labeled chemotactic peptide (fMLFK) and confirmed by measurement of myeloperoxidase activity. Neutrophil activity was assessed by 18FDG uptake. Tissue-to-blood ratios for fMLFK, 18FDG, and leukocytes were calculated to control for background. Neutrophils were counted in histologic sections of saline-perfused lungs. Bronchoalveolar lavage fluid was assessed for neutrophil migration and autoradiographed for intracellular 18FDG localization.

MEASUREMENTS AND MAIN RESULTS

Lung myeloperoxidase activity, 18FDG, and peripheral white blood cells all significantly increased in both mild and severe pancreatitis, but lung fMLFK only increased in severe pancreatitis. After correction for blood background, only 18FDG in lung (but not muscle) was significantly increased in pancreatitis (severe > mild > normal, p<.001). Histologic analysis showed significant increase in extravascular (migrated) neutrophils only in severe pancreatitis. Autoradiography of bronchoalveolar lavage fluid confirmed the 18FDG within intra-alveolar neutrophils.

CONCLUSIONS

In this pancreatitis model of acute respiratory distress syndrome, there was nonspecific and noninjurious increase of neutrophils in the lung, attributable in part to background leukocytosis and to intravascular sequestration. However, 18FDG uptake uniquely showed that interstitial and intra-alveolar neutrophil migration and activation occurred in severe but not in mild pancreatitis, consistent with clinical correlations between acute respiratory distress syndrome and severity of underlying systemic disease. 18FDG uptake, which is also accessible by positron emission tomography scanning, better quantitates the contribution of activated neutrophils to tissue injury than other measurements of neutrophil accumulation or sequestration.

Preparation and preliminary evaluation of 99mTc-EC-For-MLFK

For-Met-Leu-Phe-Lys (For-MLFK), a chemotactic peptide that binds with high affinity to granulocytes and monocytes, was labeled with 99mTc using ethylene dicysteine (EC) as the metal chelating system. EC was selected because of the rapid renal excretion of its 99mTc-complex and therefore, was expected to enhance the degree of urinary elimination of the peptide-conjugate. 99mTc-EC-For-MLFK was prepared using a preformed chelate approach. After incubation of 99mTc-EC-For-MLFK with total blood, 68.1% of the labeled peptide was associated with WBC and 86% of this cell-associated activity was bound to granulocytes. Biodistribution studies in normal mice revealed a very fast blood clearance (4.1% and 0.6% of I.D. in blood at respectively 5 and 60 min p.i.). However, elimination of the labeled peptide proceeds mainly via the hepatobiliary system (24.5% of I.D. in liver and 48.8% of I.D. in intestines at 60 min p.i.) and to a much lower degree via the kidneys (17.9% in renal system at 60 min p.i.). From these results, it is concluded that 99mTc-EC-For-MLFK is not suited to image infections, despite its high binding to granulocytes, since it leads to high, non-specific, abdominal activity.

Matrix metalloproteinase-9 promotes neutrophil migration and alveolar capillary leakage in pancreatitis-associated lung injury in the rat

BACKGROUND & AIMS

In pancreatitis-associated lung injury, neutrophils (PMN) access the lung by migration through endothelial basement membranes. We hypothesize that degeneration of the basement membrane by specific PMN-produced matrix metalloproteinases (MMPs) may facilitate this process.

METHODS

Mild or severe pancreatitis was induced in rats and the consequent pulmonary injury characterized. MMP-2 and MMP-9 activity in supernatant of PMN cultures and homogenates of lungs were assessed by zymography and Western blot. Congruence of PMN and MMP expression in lung tissue was evaluated by neutrophil depletion and fluorescent immunohistochemistry (IHC). The contribution of MMPs to PMN transmigration and lung injury was tested with the MMP inhibitor batimastat (BB-94) in vitro (PMN transmigration across matrigel chambers) and in vivo (myeloperoxidase activity and Evans blue in broncho-alveolar lavage fluid).

RESULTS

MMP-9 was highly expressed in lungs and supernatant of neutrophil cultures in severe pancreatitis, and, to a lesser degree, in mild pancreatitis. Lung IHC showed colocalization of MMP-9 and PMN. PMN depletion simultaneously reduced neutrophil infiltration and MMP-9 levels in lung tissue. Trypsin, interleukin 1 beta, and tumor necrosis factor (TNF)-alpha all potently stimulated MMP-9 release from PMN. BB-94 significantly reduced TNF-alpha-induced PMN transmigration across matrigel and ameliorated transendothelial PMN migration and protein leak in severe pancreatitis.

CONCLUSIONS

MMP-9 secretion by PMN can be stimulated by trypsin and proinflammatory cytokines and increases in pancreatitis in proportion to its severity. MMP inhibition reduces PMN transmigration and reduces resultant alveolar-capillary leakage. These findings suggest an important role for MMP-9 from PMN in the pathogenesis of pancreatitis-associated lung injury.

Expression of the adhesion molecules Mac-1 and L-selectin on neutrophils in acute pancreatitis is protease- and complement-dependent

OBJECTIVE

To examine the effect of pancreatic proteases on the expression of the adhesion molecules Mac-1 and l-selectin on neutrophils, and the role of complement activation in this process.

SUMMARY BACKGROUND DATA

Sequestration of neutrophils in the pancreatic and pulmonary microvasculature characterizes acute pancreatitis.

METHODS

Serum was collected from inbred rats after induction of necrotizing pancreatitis; trypsinogen activation peptide was measured to quantify trypsin activation. Normal rat serum was also collected and subjected to limited trypsin digestion with and without the addition of complement inhibitor. Both groups of sera were incubated in vitro with healthy leukocytes. Expression of Mac-1 and L-selectin on neutrophils was measured quantitatively by flow cytometry. To assess the consequences of these events in vivo, trypsinated serum with or without complement inhibition or control serum was infused intravenous into rats. Soybean trypsin inhibitor was added to serum before injections to block residual trypsin activity. Pancreatic and pulmonary injury was quantitated by histology, measurement of edema, and myeloperoxidase activity.

RESULTS

Mac-1 expression on neutrophils incubated with pancreatitis serum was increased compared with controls, whereas L-selectin was decreased. Neutrophils incubated with trypsinated serum also showed upregulation of Mac-1 and downregulation of L-selectin, particularly with trypsin at 10(-4) mol/L. Addition of soluble complement receptor 1 abrogated both Mac-1 upregulation and L-selectin downregulation. Lungs of animals injected with trypsinated serum showed increased edema and myeloperoxidase activity, which were reduced by soluble complement receptor 1.

CONCLUSIONS

Trypsin-generated complement activation participates in the upregulation of Mac-1 and shedding of L-selectin on neutrophils in acute pancreatitis. Protease or complement inhibition may be effective in preventing leukocyte migration and subsequent local and remote organ injury.