Acute lung injury in two experimental models of acute pancreatitis: infusion of saline or sodium taurocholate into the pancreatic duct

Prophylactic low-molecular-weight heparin administration protected against severe acute pancreatitis partially by VEGF/Flt-1 signaling in a rat model

BACKGROUND

The present study was aimed to explore the effects and the underlying mechanism of prophylactic low-molecular-weight heparin (LMWH) treatment on taurocholate-induced severe acute pancreatitis (SAP) in a rat model.

METHODS

Rat SAP model was induced by injection of 4% sodium taurocholate into the pancreatic duct. LMWH was applied half an hour before the induction of pancreatitis at the dose of 200 IU/kg subcutaneous injection. The rats were euthanized at 1 h, 6 h, and 12 h after taurocholate-induced SAP. The inflammatory and oxidative response markers were assessed. And the vascular endothelial growth factor (VEGF) and Fms-related tyrosine kinase 1 (Flt-1) expression were evaluated by immunohistochemistry (IHC) and western blot methods.

RESULTS

The expression of inflammatory and oxidative response markers increased after induction of SAP. IHC and western blot results showed the VEGF and Flt-1 expression were increased in SAP group. Prophylactic LMWH administration reduced the inflammatory and oxidative response markers expression and decreased the expression of VEGF and Flt-1.

CONCLUSIONS

This study suggested that prophylactic LMWH treatment mitigated the severity of pancreatitis in rat SAP model by anti-inflammation and oxidative response. The underlying mechanism may result from downregulating VEGF/Flt-1 signaling of LMWH in SAP rat model.

Pulmonary complications of acute pancreatitis

Introduction: Acute pancreatitis is an inflammatory condition of the pancreas, which runs a severe course in 20% of patients, wherein it is associated with high mortality. It is associated with several pleuro-pulmonary complications with variable severity that may occur either in isolation but are frequently present in combination. Clinicians need to be aware of these complications for early and appropriate management.Areas covered: We performed a systematic search of the PUBMED database (1970-2019) to identify relevant articles focusing on pleuro-pulmonary complications that may occur in patients with acute pancreatitis. We also retrieved articles describing the pathophysiological mechanisms and treatment approach of the various complications.Expert opinion: Acute pancreatitis is usually a self-limiting disease, but the development of organ failure during the course worsens the clinical outcome. Pulmonary complications usually occur early in the course of acute pancreatitis. Clinicians need to recognize the various pulmonary complications of acute pancreatitis, early during the disease, and manage them appropriately and aggressively to improve outcomes.

Development of an acute pancreatitis porcine model based on endoscopic retrograde infusion of contrast medium or sodium taurocholate

BACKGROUND/AIMS

A reproducible, endoscope-based, large animal model, of acute pancreatitis was developed to meet the need for a suitable means of preclinically testing treatments. The aim of this study was to develop an endoscope-based animal model of acute pancreatitis.

METHODS

This experimental study was conducted on six mini-pigs. The pancreatitis model was induced by infusing contrast medium (CM) or sodium taurocholate (TCA) under high pressure (100 mmHg) into the main pancreatic duct by endoscopic retrograde pancreatography. Animals were randomly allocated to three groups: a CM group, a 10% TCA group, and a 20% TCA group. Pancreatic injuries were evaluated histologically, and serum amylase and lipase levels were measured.

RESULTS

Acute pancreatitis was observed in all animals during hematologic and histologic examinations. Serum amylase and lipase levels were significantly higher (> 10 times baseline), and pancreatic edema, vacuolization of acinar cells, and hemorrhagic necrosis were observed. Severity of pancreatitis tended to be greater in the TCA groups than in the CM group as assessed using histologic scores, and degrees of pancreatitis were found to be dose-dependently related to TCA concentration.

CONCLUSION

The two endoscopic procedures described are effective and safe for creating a swine model of acute pancreatitis. The authors hope the described endoscopic methods will assist in the development of a suitable treatment strategy.

Resolvins Decrease Oxidative Stress Mediated Macrophage and Epithelial Cell Interaction through Decreased Cytokine Secretion

Background

Inflammation is a key hallmark of ALI and is mediated through ungoverned cytokine signaling. One such cytokine, interleukin-1beta (IL-1β) has been demonstrated to be the most bioactive cytokine in ALI patients. Macrophages are the key players responsible for IL-1β secretion into the alveolar space. Following the binding of IL-1β to its receptor, “activated” alveolar epithelial cells show enhanced barrier dysfunction, adhesion molecule expression, cytokine secretion, and leukocyte attachment. More importantly, it is an important communication molecule between the macrophage and alveolar epithelium. While the molecular determinants of this inflammatory event have been well documented, endogenous resolution processes that decrease IL-1β secretion and resolve alveolar epithelial cell activation and tissue inflammation have not been well characterized. Lipid mediator Aspirin-Triggered Resolvin D1 (AT-RvD1) has demonstrated potent pro-resolutionary effects in vivo models of lung injury; however, the contribution of the alveoli to the protective benefits of this molecule has not been well documented. In this study, we demonstrate that AT-RvD1 treatment lead to a significant decrease in oxidant induced macrophage IL-1β secretion and production, IL-1β-mediated cytokine secretion, adhesion molecule expression, leukocyte adhesion and inflammatory signaling.

Methods

THP-1 macrophages were treated with hydrogen peroxide and extracellular ATP in the presence or absence of AT-RvD1 (1000–0.1 nM). A549 alveolar-like epithelial cells were treated with IL-1β (10 ng/mL) in the presence or absence of AT-RvD1 (0.1 μM). Following treatment, cell lysate and cell culture supernatants were collected for Western blot, qPCR and ELISA analysis of pro-inflammatory molecules. Functional consequences of IL-1β induced alveolar epithelial cell and macrophage activation were also measured following treatment with IL-1β ± AT-RvD1.

Results

Results demonstrate that macrophages exposed to H₂O₂ and ATP in the presence of resolvins show decreased IL-1β production and activity. A549 cells treated with IL-1β in the presence of AT-RvD1 show a reduced level of proinflammatory cytokines IL-6 and IL-8. Further, IL-1β-mediated adhesion molecule expression was also reduced with AT-RvD1 treatment, which was correlated with decreased leukocyte adhesion. AT-RvD1 treatment demonstrated reduced MAP-Kinase signaling. Taken together, our results demonstrate AT-RvD1 treatment reduced IL-1β-mediated alveolar epithelial cell activation. This is a key step in unraveling the protective effects of resolvins, especially AT-RvD1, during injury.

Oxidative stress in acute pancreatitis: lost in translation?

Oxidative stress has been implicated in the pathogenesis of acute pancreatitis, a severe and debilitating inflammation of the pancreas that carries a significant mortality, and which imposes a considerable financial burden on the health system due to patient care. Although extensive efforts have been directed towards the elucidation of critical underlying mechanisms and the identification of novel therapeutic targets, the disease remains without a specific therapy. In experimental animal models of acute pancreatitis, increased oxidative stress and decreased antioxidant defences have been observed, changes also detected in patients clinically. However, despite the promise of studies evaluating the effects of antioxidants in these model systems, translation to the clinic has thus far been disappointing. This may reflect many factors involved in the design of both preclinical and clinical evaluations of antioxidant therapy, not least the fact that most experimental studies have focussed on pre-treatment rather than post-injury assessment. This review has examined evidence relating to the involvement of oxidative stress in the pathophysiology of acute pancreatitis, focussing on experimental models and the clinical experience, including the experimental techniques employed and potential of antioxidant therapy.

Blocking abdominal lymphatic flow attenuates acute hemorrhagic necrotizing pancreatitis -associated lung injury in rats

BACKGROUND

Acute hemorrhagic necrotizing pancreatitis (AHNP) is a severe acute inflammatory of pancreas that can lead to extrapancreatic organ disfunction. The lung and intestine is the most common involved organs, and abdominal lymphatic flow may contribute to AHNP- associated organ injury. In this study, we investigated the impact of thoracic duct ligation and drainage on lung and intestine injury in rats with AHNP.

METHODS

Thirty-two male Wistar rats were randomly divided into 4 groups: sham operation group, AHNP group, AHNP + ligation group and AHNP + drainage group. Rat AHNP model was induced by retrograde injection of 3.5% sodium deoxycholate into the biliopancreatic duct, and the sham operation group was injected only with saline. In AHNP + ligation group and AHNP + drainage group, thoracic duct was ligated or drainaged before model induction. At 6 h after model induction, the bronchoalveolar lavage fluid (BALF) were collected for determination of tumor necrosis factor-alpha (TNF-alpha), and the tissues of lung, intestine and pancrease were harvested individually for pathohistological evaluation and the myeloperoxidase (MPO) activity determination. In addition, the activity of serum amylase and diamine oxidase (DAO) was determined in each group.

RESULTS

The pathohistological damage and MPO of lung, intestine and pancrease, TNF-alpha of BALF, serum amylase and DAO were all increased in AHNP group compared to those in sham operation group (P < 0.05). In AHNP + ligation group, the pathohistological damage and MPO of lung and TNF-alpha of BALF were reduced, but the pathohistological damage and MPO of intestine and pancrease were increased compared with AHNP group (P < 0.05), however the activity of serum amylase and DAO was no changed. In AHNP + drainage group, the pathohistological damage and MPO of lung, intestine and pancrease, TNF-alpha of BALF, serum amylase and DAO were all reduced compared to those in AHNP group (P < 0.05).

CONCLUSIONS

Our finding suggest that thoracic duct ligation can reduce neutrophil infiltration and TNF-alpha release and then attenuates lung injury in rats with AHNP, but aggravates the injury of intestine and pancrease. While thoracic duct drainage attenuates the injury of lung, intestine and pancreaseat the same time in rats with AHNP.

Lung injury in acute pancreatitis: mechanisms underlying augmented secondary injury

Acute lung injury (ALI) and its more severe form, the acute respiratory distress syndrome (ARDS), are common complications of acute pancreatitis (AP). ALI/ARDS contribute to the majority of AP-associated deaths, particularly in the setting of secondary infection. Following secondary pulmonary infection there can be an exacerbation of AP-associated lung injury, greater than the sum of the individual injuries alone. The precise mechanisms underlying this synergism, however, are not known. In this review we discuss the main factors contributing to the development of augmented lung injury following secondary infection during AP and review the established models of AP in regard to the development of associated ALI.

L-Arginine-induced acute pancreatitis results in mild lung inflammation without altered respiratory mechanics

Acute lung injury is a common complication of acute pancreatitis (AP) and contributes to the majority of AP-associated deaths. Although some aspects of AP-induced lung inflammation have been demonstrated, investigation of resultant changes in lung function is limited. The aim of this study was to characterize acute lung injury in L-arginine-induced AP. Seven groups of male Sprague-Dawley rats (n = 4-10/group) received 2 intraperitoneal (i.p.) injections of L-arginine (250 mg/100 g) at 6, 12, 24, 36, 48, or 72 hours before measurement of lung impedance mechanics. Control rats (n = 10) received i.p. saline. Bronchoalveolar lavage (BAL), plasma, and pancreatic and lung tissue were collected to determine pancreatic and lung measures of acute inflammation. AP developed between 6 and 36 hours, as indicated by increased pancreatic abnormal acinar cells, myeloperoxidase (MPO) activity, edema, and plasma amylase activity, before beginning to resolve by 72 hours. In the lung, MPO activity increased (2.4-fold) from 12 hours, followed by a modest increase in lung edema at 48 hours, with increased BAL cell count (2.5-fold) up to 72 hours (P < .05). In contrast, no significant changes in lung mechanics were evident over the same period. Despite measurable lung inflammation, no significant deterioration in respiratory function resulted from L-arginine-induced AP.

Caerulein-induced acute pancreatitis results in mild lung inflammation and altered respiratory mechanics

Acute lung injury is a common complication of acute pancreatitis (AP) and contributes to the majority of AP-associated deaths. Although some aspects of AP-induced lung inflammation have been demonstrated, investigation of resultant changes in lung function is limited. The aim of this study was to characterize lung injury in caerulein-induced AP. Male Sprague Dawley rats (n = 7-8/group) received 7 injections of caerulein (50 μg/kg) at 12, 24, 48, 72, 96, or 120 hours before measurement of lung impedance mechanics. Bronchoalveolar lavage (BAL), plasma, pancreatic, and lung tissue were collected to determine pancreatic and lung measures of acute inflammation. AP developed between 12 and 24 hours, as indicated by increased plasma amylase activity and pancreatic myeloperoxidase (MPO) activity, edema, and abnormal acinar cells, before beginning to resolve by 48 hours. In the lung, MPO activity peaked at 12 and 96 hours, with BAL cytokine concentrations peaking at 12 hours, followed by lung edema at 24 hours, and BAL cell count at 48 hours. Importantly, no significant changes in BAL protein concentration or arterial blood gas-pH levels were evident over the same period, and only modest changes were observed in respiratory mechanics. Caerulein-induced AP results in minor lung injury, which is not sufficient to allow protein permeability and substantially alter respiratory mechanics.

Emodin enhances alveolar epithelial barrier function in rats with experimental acute pancreatitis

AIM: To investigate the effect of emodin on expression of claudin-4, claudin-5 and occludin, as well as the alveolar epithelial barrier in rats with pancreatitis induced by sodium taurocholate.

METHODS: Experimental pancreatitis was induced by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. Emodin was injected via the external jugular vein 3 h after induction of acute pancreatitis. Rats from sham operation group and acute pancreatitis group were injected with normal saline (an equivalent volume as emodin) at the same time point. Samples of lung and serum were obtained 6 h after drug administration. Pulmonary morphology was examined with HE staining. Pulmonary edema was estimated by measuring water content in lung tissue samples. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) level were measured by enzyme-linked immunospecific assay. Serum amylase and pulmonary myeloperoxidase (MPO) activity were detected by spectrophotometry. Alveolar epithelial barrier was assessed by pulmonary dye extravasation. Expression of claudin-4, claudin-5 and occludin in lung tissue samples was examined by immunohistology, quantitative real-time reverse transcription polymerase chain reaction and Western blotting analysis, respectively.

RESULTS: Pancreatitis-associated lung injury was characterized by pulmonary edema, leukocyte infiltration, alveolar collapse, and elevated serum amylase level. The pulmonary damage, pulmonary pathological scores, serum amylase and MPO activity, TNF-α and IL-6 levels, and wet/dry ratio were decreased in rats after treatment with emodin. Immunostaining of claudin-4, claudin-5 and occludin was detected in lung tissue samples from rats in sham operation group, which was distributed in alveolar epithelium, vascular endothelium, and bronchial epithelium, respectively. The mRNA and protein expression levels of claudin-4, claudin-5 and occludin in lung tissue samples were markedly decreased, the expression level of claudin-4, claudin-5 and occluding was increased, and the pulmonary dye extravasation was reduced in lung tissue samples from rats with acute pancreatitis after treatment with emodin.

CONCLUSION: Emodin attenuates pulmonary edema and inflammation, enhances alveolar epithelial barrier function, and promotes expression of claudin-4, claudin-5 and occludin in lung tissue samples from rats with acute pancreatitis.

Hydrogen sulfide attenuates the pathogenesis of pulmonary fibrosis induced by bleomycin in rats

The present study investigated the role of the endogenous cystathionine gamma-lyase (CSE) / hydrogen sulfide pathway in the pathogenesis of pulmonary fibrosis. Rats treated with intratracheal bleomycin were exposed either to the H2S donor NaHS or to saline. The results on day 7 showed that plasma H2S concentration and pulmonary CSE activity (H2S production rate) were significantly lower in rats treated with bleomycin and saline (fibrosis-alone) than in controls, whereas on day 28 plasma H2S concentration was higher and pulmonary CSE activity was the same as that of controls. The relative CSE mRNA level in the lungs of rats treated with bleomycin was significantly higher than control values on days 7 and 28. After exposure to NaHS, the total lung hydroxyproline content and the malondialdehyde (MDA) content were both significantly lower, with no difference observed between NaHS high-dose and low-dose treatments. Further, MDA formation stimulated by the free radical-generating system (FRGS) in vitro was lower in lung tissue incubated with NaHS than it was in tissue incubated with FRGS alone. These results suggest that NaHS administration ameliorated the pulmonary fibrosis induced by bleomycin in rats and that this protective effect of H2S may be mediated by its antioxidative action.

Leflunomide: is a new oral agent in treatment of acute pancreatitis?

OBJECTIVES

Nuclear factor-kappaB (NF-kappaB) is a potent mediator in several steps of acute pancreatitis. Leflunomide is a novel immunomodulating drug that is also a potent inhibitor of NF-kappaB activation. The aim of this study was to investigate the effects of leflunomide pretreatment in severe necrotizing pancreatitis in rats.

METHODS

Fifty rats were randomly divided into 5 groups. Severe necrotizing pancreatitis was induced by retrograde injection of 3% sodium taurocholate into the common biliopancreatic duct. Leflunomide (10 mg/kg) was given intragastrically for 2 doses before the experiment. Serum amylase activity, pancreatic histopathologic condition, malondialdehyde level, myeloperoxidase enzyme activity, nitric oxide level, and pulmonary changes were assessed.

RESULTS

Leflunomide pretreatment significantly ameliorated pancreatic hemorrhage, edema, and neutrophil infiltration and decreased histopathological score compared with the untreated severe necrotizing pancreatitis group (pathological score [mean +/- SEM]: 6.70 +/- 1.19 vs 12.36 +/- 1.08 in the leflunomide treated and untreated groups, respectively, P < 0.01). Pulmonary changes was decreased in the leflunomide treated group (3.90 +/- 0.45 vs 4.75 +/- 0.25, respectively). Change in pulmonary alveolar distention was significant. Although serum amylase levels also decreased, the difference was not significant (5922 +/- 3290 vs 15547 +/- 5090 U/mL).

CONCLUSIONS

Leflunomide is a beneficial agent in the severe form of acute pancreatitis in rats and should be considered as a potential agent for treatment of acute pancreatitis.

A crucial role of nitric oxide in acute lung injury secondary to the acute necrotizing pancreatitis

To investigate the role of nitric oxide (NO) in acute lung inflammation and injury secondary to acute necrotizing pancreatitis (ANP), 5% sodium taurocholate was retrogradely injected into the biliopancreatic duct of rats to ANP model. These ANP rats were given L-Arginine (L-Arg, 100 mg/kg), L-NAME (10 mg/kg), or their combination by intraperitoneal injection 30 min prior to ANP induction. At 1, 3, 6, and 12 hours after ANP induction, lung NO production, and inducible NO synthase (iNOS) expression were measured. Lung histopathological changes, bronchoalveolar lavage (BAL) protein concentration, proinflammatory mediators tumor necrotic factor alpha (TNF-α), and lung tissue myeloperoxidase (MPO) activity were examined. Results showed that NO production and iNOS mRNA expression in alveolar macrophages (AMs) were significantly increased along with significant increases in lung histological abnormalities and BAL proteins in the ANP group, all of which were further enhanced by pretreatment with L-Arg and attenuated by pretreatment with L-NAME, respectively. These markers were slightly attenuated by pretreatment with combination of L-Arg + L-NAME, suggesting that NO is required for initiating the acute lung damage in ANP rats, and also that L-Arg-enhanced lung injury is mediated by its NO generation rather than its direct effect. MPO activity and TNF-α expression in lung were upregulated in the ANP rats and further enhanced by pretreatment with L-Arg and attenuated by pretreatment with L-NAME, respectively. These results suggest that overproduction of NO mediated by iNOS in the lung is required for the acute lung inflammation and damage secondary to ANP.

Acute pancreatitis: hypertonic saline increases heat shock proteins 70 and 90 and reduces neutrophil infiltration in lung injury

OBJECTIVES

Acute pancreatitis (AP) protease release induces lung parenchymal destruction via matrix metalloproteinases (MMPs), a neutrophil (polymorphonuclear leukocyte)-dependent process. Recent studies in hemorrhagic shock revealed that hypertonic saline (HTS) has an anti-inflammatory effect and can inhibit a variety of neutrophil functions. The aim of this study was to determine whether HTS and its actions in the pathway of neutrophil migration, MMPs, and heat shock proteins (HSPs) are effective in protecting the lung from injury associated with AP.

METHODS

We determined neutrophil infiltration and expressions of MMPs and HSPs in the lung tissue after AP induced by retrograde infusion of 2.5% of sodium taurocholate.

RESULTS

Animals submitted to AP that received HTS compared with those who received normal saline presented with increased HSP70 and HSP90 expressions and reduced myeloperoxidase levels and MMP-9 expression and activity.

CONCLUSIONS

Our data raised the hypothesis that a sequence of HTS lung protection events increases HSP70 and HSP90, inhibiting infiltration of neutrophils and their protease actions in the lung.

Saline infusion through the pancreatic duct leads to changes in calcium homeostasis similar to those observed in acute pancreatitis

This work focuses on studying the early events associated with pancreatic damage after retrograde infusion through the pancreatic duct in rats. We have analyzed changes in calcium homeostasis and secretory response in pancreatic acini from rats with taurocholate-induced acute pancreatitis. Moreover, in order to test whether pancreatic duct manipulation can trigger damage inside pancreatic acinar cells, we have studied both parameters in acini from animals infused with saline. Our study demonstrates that taurocholate causes evident damage to acinar cells, impairing both calcium homeostasis and secretory response to CCK. In saline, a significant decrease in calcium cytosolic response to CCK was observed. Calcium disturbances similar to those observed in acute pancreatitis appear before secretion blockade and inflammation processes in saline treated rats. These results could be interesting since pancreatitis is associated to clinical procedures that require duct manipulation such as endoscopic retrograde cholangiopancreatography.

Trypsin is the culprit of multiple organ injury with severe acute pancreatitis

The consistently high proportion of early deaths in patients with severe acute pancreatitis (SAP) has been associated mainly with the development of multiple organ dysfunction syndromes (MODS). So far, scholars believed that the main reasons of MODS with SAP are systemic microcirculation dysfunction and inflammatory mediator induced cascading effect on the basis of pancreas digesting itself. However, there is some special pathological phenomenon in the process of SAP which could not be explained by current theories. First, it has been evident that the pancreatic tissue bleeding and necrosis is special pathological change in pancreas autodigestive effect from digestive enzymes such as trypsin in SAP. However, we found that the liver, the lung, the intestine, the brain and the kidney have the same pathological changes in experimental animal models of SAP. Secondly, unlike the general inflammatory response, a significantly amount of bloody ascites and pleural effusion was often in patients with SAP and in experimental SAP animal models. It indicates that the vascular permeability significantly increased leading to the red blood cells extravasation. Thirdly, apart from dual blood supply, liver bears a strong compensatory function. However, liver has the highest incidence of injury in SAP when compared with other organs. In addition, we found a very interesting phenomenon after reading texts and clinical records. From the pancreatic venous drainage from the point of view, the farther the organ from the pancreas, the lower injury incidence rate observed. How to explain these mysteries? We postulate that the trypsin is the culprit of multiple organs dysfunction in SAP. The activated trypsin destroy the pancreas itself, causing pancreatic tissue bleeding and necrosis, at the same time, through venous flow it flow into the blood circulation and destroy the vascular endothelial barrier, leading to highly increased vascular permeability. So, a large number of bloody exudates leakages from the vessels, resulting in patients early circulatory disorders, multiple organ bleeding, bloody pleural effusion and ascites. This pathological change is the most apparent in the liver because the liver is the first organ to receive the pancreatic venous flow having the highest concentration of trypsin. Thus, if the quantity of trypsin decreases in blood, its ability to damage other organs also shows a trend of gradually reducing. These mysteries can be explained by this hypothesis and might help us to understand more clearly about the mechanism of SAP-associated MODS.

Initiation of acute pancreatitis by heparan sulphate in the rat

OBJECTIVE

The initiating events in the onset of pancreatitis are poorly understood. Possible candidates may be endogenous ligands, acting on receptors within ductal, acinar or stellate cells, which have previously been shown to cause a systemic inflammatory response syndrome. The aim of this study was to investigate whether acute pancreatitis could be induced by heparan sulphate (HS)infused into the pancreatic ducts in the rat.

MATERIAL AND METHODS

Retrograde biliary-pancreatic infusion of heparan sulphate of different structures, taurodeoxycholate (TDC) or phosphate buffered saline (PBS) was performed. Local pancreatic inflammation was evaluated after 6 h by means of morphological evaluation, neutrophil and macrophage infiltration and levels of plasma amylase. Systemic inflammation was evaluated by measuring plasma IL-6, MCP-1 and CINC-1 concentrations.

RESULTS

Heparan sulphate induced a local inflammatory response visualized as a rapid infiltration of neutrophils and macrophages into the pancreas. Heparan sulphate induced inflammation and oedema without causing damage to acinar cells, as measured by morphological changes and plasma amylase concentrations. Furthermore, an increase in serum concentrations of CINC-1 and IL-6 was seen. The positive control (TDC) had increased levels of all variables analysed and the negative control (heparan sulphate administered intraperitoneally) was without effects.

CONCLUSIONS

Our findings suggest a receptor-mediated innate immune response of the pancreatic cells induced by heparan sulphate. This finding may be helpful in elucidating some of the mechanisms involved during the initiation of pancreatitis, as well as in the search for a potential future therapeutic application.

Protective effects of erythropoietin against acute lung injury in a rat model of acute necrotizing pancreatitis

AIM

To investigate the effect of exogenous erythro-poietin (EPO) administration on acute lung injury (ALI) in an experimental model of sodium taurodeoxycholate- induced acute necrotizing pancreatitis (ANP).

METHODS

Forty-seven male Wistar albino rats were randomly divided into 7 groups: sham group (n = 5), 3 ANP groups (n = 7 each) and 3 EPO groups (n = 7 each). ANP was induced by retrograde infusion of 5% sodium taurodeoxycholate into the common bile duct. Rats in EPO groups received 1000 U/kg intramuscular EPO immediately after induction of ANP. Rats in ANP groups were given 1 mL normal saline instead. All animals were sacrificed at postoperative 24 h, 48 h and 72 h. Serum amilase, IL-2, IL-6 and lung tissue malondialdehyde (MDA) were measured. Pleural effusion volume and lung/body weight (LW/BW) ratios were calculated. Tissue levels of TNF-alpha, IL-2 and IL-6 were screened immunohistochemically. Additionally, ox-LDL accumulation was assessed with immune-fluorescent staining. Histopathological alterations in the lungs were also scored.

RESULTS

The mean pleural effusion volume, calculated LW/BW ratio, serum IL-6 and lung tissue MDA levels were significantly lower in EPO groups than in ANP groups. No statistically significant difference was observed in either serum or tissue values of IL-2 among the groups. The level of tumor necrosis factor-alpha (TNF-alpha) and IL-6 and accumulation of ox-LDL were evident in the lung tissues of ANP groups when compared to EPO groups, particularly at 72 h. Histopathological evaluation confirmed the improvement in lung injury parameters after exogenous EPO administration, particularly at 48 h and 72 h.

CONCLUSION

EPO administration leads to a significant decrease in ALI parameters by inhibiting polymorphonuclear leukocyte (PMNL) accumulation, decreasing the levels of proinflammatory cytokines in circulation, preserving microvascular endothelial cell integrity and reducing oxidative stress-associated lipid peroxidation and therefore, can be regarded as a cytoprotective agent in ANP-induced ALI.

Taurocholate-induced pancreatitis: a model of severe necrotizing pancreatitis in mice

OBJECTIVES

The outcome from acute pancreatitis depends on the severity of systemic complications. To be able to investigate mechanisms underlying the development of these systemic complications in acute pancreatitis in both wild-type and genetically engineered animal models, a mouse model of severe necrotizing pancreatitis was developed and characterized.

METHODS

Pancreatitis was induced by retrograde infusion of sodium taurocholate into the common bile duct in mice. After determining the optimum volume and concentration of taurocholate, the pancreatic damage and systemic inflammatory response were compared with those in cerulein-induced pancreatitis.

RESULTS

Pancreatic damage was higher in taurocholate pancreatitis than hyperstimulation-induced pancreatitis (24 hours: cerulein, 5.8 +/- 0.2 points; taurocholate, 14.8 +/- 0.8 points; P < 0.001) and mortality reached up to 60% within the first 24 hours after taurocholate administration. Pulmonary damage was detected, as measured by an increase in albumin in bronchoalveolar lavage fluid only in taurocholate-induced pancreatitis (12 hours: cerulein, 97.1 +/- 22.83 mg/g of protein; taurocholate, 234.0 +/- 32.7 mg/g of protein; P < 0.001). Furthermore, plasma interleukin 6 concentration was significantly elevated in mice with taurocholate-induced pancreatitis (12 hours: cerulein, 2.6 +/- 6.1 pg/mL; taurocholate, 2168.8 +/- 941.7 microg/mL; P < 0.001) as compared with all other groups.

CONCLUSIONS

Taurocholate pancreatitis is a reliable model for severe necrotizing pancreatitis in mice with significantly greater pancreatic damage and systemic inflammatory response in comparison with cerulein-induced pancreatitis.

Up-regulation of Toll-like receptor 4 was suppressed by emodin and baicalin in the setting of acute pancreatitis

Acute pancreatitis (AP) activates the systemic inflammatory response and is potentially lethal. Recent studies demonstrated that pancreatic enzymes could induce cytokine expression via Toll-like receptor 4 (TLR4) signal pathway, indicating a possible role of TLR4 in local pancreatic injury and systemic inflammatory response. Emodin, an anthraquinone derivative from Radix et Rhizoma Rhei, and baicalin, a flavone from Scutellaria baicalensis Georgi, both have been reported to possess anti-inflammatory activities. In present study, we investigated the combined effect of emodin and baicalin on pancreatic damage and pancreatitis associated lung injury, as well as tissue TLR4 expression in the setting of AP. The results showed that combination of emodin and baicalin significantly reduced serum amylase, tumor necrosis factor-alpha and interleukin-6, attenuated pancreatic and pulmonary damage, also suppressed TLR4 expression in pancreas and lung. It could be speculated that amelioration of pancreatic and pulmonary damage by emodin and baicalin might contribute, in part at least, to the suppression of TLR4 expression. The present study provides beneficial evidence as to simultaneous treatment for AP, and also suggests an important role of TLR4 in pathophysiology of AP.

Protective effects of erythropoietin against acute lung injury in a rat model of acute necrotizing pancreatitis

AIM: To investigate the effect of exogenous erythro-poietin (EPO) administration on acute lung injury (ALI) in an experimental model of sodium taurodeoxycholate-induced acute necrotizing pancreatitis (ANP).

METHODS: Forty-seven male Wistar albino rats were randomly divided into 7 groups: sham group (n = 5), 3 ANP groups (n = 7 each) and 3 EPO groups (n = 7 each). ANP was induced by retrograde infusion of 5% sodium taurodeoxycholate into the common bile duct. Rats in EPO groups received 1000 U/kg intramuscular EPO immediately after induction of ANP. Rats in ANP groups were given 1 mL normal saline instead. All animals were sacrificed at postoperative 24 h, 48 h and 72 h. Serum amilase, IL-2, IL-6 and lung tissue malondialdehyde (MDA) were measured. Pleural effusion volume and lung/body weight (LW/BW) ratios were calculated. Tissue levels of TNF-α, IL-2 and IL-6 were screened immunohistochemically. Additionally, ox-LDL accumulation was assessed with immune-fluorescent staining. Histopathological alterations in the lungs were also scored.

RESULTS: The mean pleural effusion volume, calculated LW/BW ratio, serum IL-6 and lung tissue MDA levels were significantly lower in EPO groups than in ANP groups. No statistically significant difference was observed in either serum or tissue values of IL-2 among the groups. The level of tumor necrosis factor-α (TNF-α) and IL-6 and accumulation of ox-LDL were evident in the lung tissues of ANP groups when compared to EPO groups, particularly at 72 h. Histopathological evaluation confirmed the improvement in lung injury parameters after exogenous EPO administration, particularly at 48 h and 72 h.

CONCLUSION: EPO administration leads to a significant decrease in ALI parameters by inhibiting polymorphonuclear leukocyte (PMNL) accumulation, decreasing the levels of proinflammatory cytokines in circulation, preserving microvascular endothelial cell integrity and reducing oxidative stress-associated lipid peroxidation and therefore, can be regarded as a cytoprotective agent in ANP-induced ALI.

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.

PPAR-gamma knockout in pancreatic epithelial cells abolishes the inhibitory effect of rosiglitazone on caerulein-induced acute pancreatitis

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists, such as the thiazolidinediones (TZDs), decrease acute inflammation in both pancreatic cell lines and mouse models of acute pancreatitis. Since PPAR-gamma agonists have been shown to exert some of their actions independent of PPAR-gamma, the role of PPAR-gamma in pancreatic inflammation has not been directly tested. Furthermore, the differential role of PPAR-gamma in endodermal derivatives (acini, ductal cells, and islets) as opposed to the endothelial or inflammatory cells is unknown. To determine whether the effects of a TZD, rosiglitazone, on caerulein-induced acute pancreatitis are dependent on PPAR-gamma in the endodermal derivatives, we created a cell-type specific knock out of PPAR-gamma in pancreatic acini, ducts, and islets. PPAR-gamma knockout animals show a greater response in some inflammatory genes after caerulein challenge. The anti-inflammatory effect of rosiglitazone on edema, macrophage infiltration, and expression of the proinflammatory cytokines is significantly decreased in pancreata of the knockout animals compared with control animals. However, rosiglitazone retains its effect in the lungs of the pancreatic-specific PPAR-gamma knockout animals, likely due to direct anti-inflammatory effect on lung parenchyma. These data show that the PPAR-gamma in the pancreatic epithelia and islets is important in suppressing inflammation and is required for the anti-inflammatory effects of TZDs in acute pancreatitis.

Acute pancreatitis: animal models and recent advances in basic research

Acute pancreatitis (AP) is characterized by edema, acinar cell necrosis, hemorrhage, and severe inflammation of the pancreas. Patients with AP present with elevated blood and urine levels of pancreatic digestive enzymes, such as amylase and lipase. Severe AP may lead to systemic inflammatory response syndrome and multiorgan dysfunction syndrome, which account for the high mortality rate of AP. Although most (>80%) cases of AP are associated with gallstones and alcoholism, some are idiopathic. Although the pathogenesis of AP has not yet been elucidated, a common feature is the premature activation of trypsinogen within pancreatic tissues, which triggers autodigestion of the gland. Recent advances in basic research suggest that etiologic factors including cyclooxygenase-2, substance P, and angiotensin II may have novel roles in this disease. Basic research data obtained thus far have been based on animal models of AP ranging from mild edematous pancreatitis to severe necrotizing pancreatitis. In view of this, an adequate selection of experimental animal models is of paramount importance. Notwithstanding these animal models, it should be emphasized that none of these models mimic the clinical situation where varying degrees of severity usually occur. In this review, commonly used animal models of AP will be critically evaluated. A discussion of recent advances in our knowledge about AP risk factors is also included.

Time course of lung injury in rat acute pancreatitis

OBJECTIVE

Lung injury is a severe complication of acute pancreatitis that increases the mortality rate of the disease. The pathophysiology of acute pancreatitis has been studied in several experimental models, but the kinetics of pulmonary complications in relation to the pancreatic disease is not completely understood. We then studied the severity of acute pancreatitis-associated lung injury over 18h in rats that had taurocholic acid injection in the pancreatic duct and determined whether blood collected from rats with pancreatitis is toxic enough to induce injury in normal lungs.

DESIGN AND SETTING

Prospective, randomized, and controlled animal study in an animal research laboratory in a university hospital.

INTERVENTIONS

We isolated lungs from rats with acute pancreatitis 2, 6, and 18h after taurocholic acid injection in the biliopancreatic duct and perfused them with blood collected from the same rats. Additionally, blood collected from rats with acute pancreatitis (time-points: 2 and 6h) was perfused in normal lungs.

MEASUREMENTS AND RESULTS

Taurocholic acid injection induced a severe pancreatic injury that started as early as 2h after the injection and persisted without recovery over the 18-h study period. In contrast, the pulmonary injury was transient, appearing at the 6-h time point with recovery by the end of the study. Pulmonary injury was moderate and evidenced mostly during lung reperfusion. Interestingly, blood collected at the 2-h time point in pancreatic rats induced pulmonary injury in normal lungs while blood collected at the 6-h time-point was not toxic.

CONCLUSIONS

While pancreatic injury persists over the full experimental period, pulmonary injury is transient in our experimental model. The recovery of lung injury by 18h might be explained by a decrease in the overall toxicity of pancreatic blood over time.

Blockade of interleukin 6 accelerates acinar cell apoptosis and attenuates experimental acute pancreatitis in vivo

BACKGROUND

It remains unclear whether interleukin (IL) 6 plays a role in initiating either the inflammatory or antiapoptotic responses in severe acute pancreatitis. This study examined the effect of neutralizing antibody against IL-6 on the induction of pancreatic acinar cell apoptosis and attenuation of the severity of severe acute pancreatitis.

METHODS

Experiments were conducted on laboratory mice with severe acute pancreatitis induced by lipopolysaccharide injection following six injections of caerulein at intervals of 6 h. Neutralizing monoclonal anti-IL-6 antibody was administered either 5 min or 2 h after the first caerulein injection. Apoptosis in pancreatic sections was determined by the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labelling method.

RESULTS

Administration of caerulein and LPS induced an increase in serum amylase and IL-6 levels, severe acute pancreatitis, pancreatitis-associated lung injury, and phosphorylation of signal transducer and activator of transcription (STAT) 3 in the pancreas. A neutralizing antibody against IL-6 effectively suppressed these responses. Application of IL-6 neutralizing antibody caused the induction of apoptosis in the pancreatic acinar cells of mice with acute pancreatitis.

CONCLUSION

Blocking IL-6 suppresses STAT-3 activation in the pancreas and consequently attenuates the severity of severe acute pancreatitis by promotion of pancreatic acinar cell apoptosis.

Lung compliance, plasma electrolyte levels and acid-base balance are affected by scorpion envenomation in anesthetized rats under mechanical ventilation

To determine the effects of Tityus serrulatus scorpion toxin on lung compliance and resistance, ionic equilibrium and acid-base balance over time in anesthetized and mechanically ventilated rats, we measured air flow, tracheal and esophageal pressure. Lung volume was obtained by electronic integration of airflow signal. Arterial blood samples were collected through a catheter at baseline (before) and 5, 15, 30 and 60 min after scorpion toxin injection for arterial blood gases, bicarbonate, and alkali reserve levels as well as for, sodium, potassium, magnesium, glucose, lactate, hematocrit, and osmolality analysis. Injection of the gamma fraction of the T. serrulatus scorpion venom in rats under mechanical ventilatory support leads to a continuous decrease in lung compliance secondary to pulmonary edema, but no change in airway resistance. The changes in arterial blood gases characterizing metabolic acidosis were accompanied by an increase in arterial lactate and glucose values, suggesting a scorpion toxin-induced lactic acidosis, in association with poor tissue perfusion (hypotension and low cardiac output). Moreover, scorpion toxin injection resulted in hyperosmolality, hyperkalemia, hypermagnesemia and an increase in hematocrit. The experiments have shown a clinically relevant animal model to study severe scorpion envenoming and may help to better understand the scorpion envenoming syndrome.

Infliximab: a new therapeutic agent in acute pancreatitis?

PURPOSE

Tumor necrosis factor alpha (TNF-alpha) has a central role in the pathogenesis of acute pancreatitis and related systemic complications. The aim of this study is to investigate the therapeutic effectiveness of monoclonal TNF antibody (infliximab) in acute edematous and severe necrotizing pancreatitis models in rats.

METHODS

One hundred rats were randomly divided into 10 groups. Acute edematous pancreatitis (AEP) was induced by injection of cerulein 20 microg/kg 4 times subcutaneously at hourly intervals. Severe necrotizing pancreatitis (SNP) was induced by retrograde injection of 3% taurocholate into the common biliopancreatic duct. Infliximab 8 mg/kg was given via intravenous infusion. Serum amylase activity, pancreatic histopathology, myeloperoxidase enzyme activity (MPO), and pulmonary changes were assessed.

RESULTS

Infliximab treatment significantly decreased serum amylase activity (11939 +/- 1914 U/L versus 3458 +/- 915 U/L, P < 0.001) and histopathologic score (4.1 +/- 0.5 versus 1.5 +/- 0.3, P < 0.001) in AEP. It also suppressed neutrophil infiltration and MPO activity of the pancreatic tissue. In SNP, infliximab treatment was found to decrease pathologic score (9.4 +/- 1.2 versus 3.6 +/- 0.8, P < 0.001) and serum amylase activity (20442 +/- 2375 versus 8990 +/- 1730, P < 0.01). It ameliorated both parenchymal and fatty tissue necrosis of the pancreas. Infliximab also alleviated alveolar edema and acute respiratory distress syndrome like pulmonary complications, but the difference was not significant.

CONCLUSIONS

Chimeric TNF antibody, infliximab, should be evaluated for treatment of acute pancreatitis.

Increased expression of 19-kD interacting protein-3-like protein and the relationship to apoptosis in the lung of rats with severe acute pancreatitis

OBJECTIVE

The aim of the present study was to determine the underlying cellular mechanisms in the pancreas after acute pancreatitis and to study the pathogenesis of pancreatitis-associated lung injury. We applied a differential display analysis to normal pancreas and to the pancreas with acute pancreatitis in rats, and we examined the expression of the identified gene in the lung as well as the pancreas after acute pancreatitis.

DESIGN

Controlled animal study.

SETTING

Research laboratory of an academic institution.

SUBJECTS

Ninety male Wistar rats.

INVESTIGATIONS

Pancreatitis was induced by retrograde intraductal infusion of 4% sodium taurocholate (100 microL/100 g of body weight). Data were compared with data from controls (sham).

MEASUREMENTS AND MAIN RESULTS

We cloned some expressed sequence tags and identified one complementary DNA fragment. The deduced protein was a polypeptide of 218 amino acids, which was almost identical to human 19-kD interacting protein-3-like (NIP3L) protein. The expression of rat NIP3L identified in this study increased slightly in the pancreas after induction of acute pancreatitis but showed a marked increase in the lung by both Northern and Western blot analysis. NIP3L immunoreactivity was noted in alveolar and epithelial cells of the control (sham) lung, and the immunoreactivity in these cells was elevated after induction of acute pancreatitis. Moreover, acute pancreatitis increased terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive alveolar and bronchiolar cells in the lung.

CONCLUSION

NIP3L may be involved in lung injury, which is one of the major causes of death in cases of severe acute pancreatitis.

Acute lung injury in experimental pancreatitis in rats: pulmonary protective effects of crotapotin and N-acetylcysteine

Respiratory complications are major factors contributing to death in acute pancreatitis. However, the mechanisms of these pulmonary complications are not completely elucidated. We studied the effects of pretreatment with purified crotapotin (a phospholipase A2 inhibitor), N-acetylcysteine (a reactive oxygen species inhibitor), and a combination of both on the pulmonary mechanical and morphometric changes secondary to severe acute necrohemorrhagic pancreatitis in Wistar rats. A total of 69 male Wistar rats were studied. Pancreatitis was induced by infusion of 0.5 mL of a 4% solution of sodium taurocholate into the biliopancreatic duct. Crotapotin, N-acetylcysteine, or a combination of both was given intraperitoneally 30 min before inducing pancreatitis. Data were compared with data from sham-operated animals with or without those pretreatments. The severity of pancreatic and pulmonary injuries was evaluated 4 h after inducing pancreatitis by morphometric and pulmonary mechanical studies. N-acetylcysteine prevented the development of alveolar edema, alveolar distention, and collapse. Crotapotin prevented alveolar distention and collapse, and pulmonary dynamic elastance increase. When used in combination, crotapotin and N-acetylcysteine prevented both pulmonary morphological and mechanical changes induced by acute pancreatitis, suggesting an increase in protective effect when these drugs are used together compared with individual effects. However, the severity of pancreatic necrosis and the increase in polymorphonuclear cells in alveolar septa induced by pancreatitis were not reduced by previous administration of crotapotin, N-acetylcysteine, or both. These results suggest that the protective effects of these drugs are probably due to an extra-pancreatic action in the circulation, or even directly in the lung.