Pulmonary vascular injury in pancreatitis: evidence for a major role played by pancreatic elastase

Combined use of extracorporeal membrane oxygenation with interventional surgery for acute pancreatitis with pulmonary embolism: A case report

BACKGROUND

Acute pancreatitis (AP) is an acute inflammatory process of the pancreas characterized by self-digestion of pancreatic tissue, which can trigger a systemic inflammatory response. Venous thrombosis, resulting from a hypercoagulable state, is a vascular complication of AP. AP complicated by pulmonary embolism (PE) is very rare, and the combined use of extracorporeal membrane oxygenation (ECMO) with a vascular interventional procedure for AP complicated by PE is even rarer.

CASE SUMMARY

A 32-year-old man with a history of obesity developed rapidly worsening AP secondary to hypertriglyceridemia. During treatment, the patient developed chest tightness, shortness of breath, and cardiac arrest. Computed tomography (CT) scans of his upper abdomen were consistent with pancreatitis. PE was identified by chest CT angiography involving the right main pulmonary artery and multiple lobar pulmonary arteries. The patient’s D-dimer level was significantly elevated (> 20 mg/L). The patient received high-frequency oxygen inhalation, continuous renal replacement therapies, anti-infective therapy, inhibition of pancreatic secretion, emergent endotracheal intubation, and advanced cardiac life support with cardiopulmonary resuscitation. Following both ECMO and a vascular interventional procedure, the patient recovered and was discharged.

CONCLUSION

PE is a rare but potentially lethal complication of AP. The early diagnosis of PE is important because an accurate diagnosis and timely interventional procedures can reduce mortality. The combined use of ECMO with a vascular interventional procedure for AP complicated by PE can be considered a feasible treatment method. A collaborative effort between multiple teams is also vital.

Acute pancreatitis with pulmonary embolism: A case report

BACKGROUND

Acute pancreatitis (AP) is a common critical disease of the digestive system that is often associated with multiple complications. Vascular complications are relatively rare and are one of the causes of death. AP complicated with pulmonary embolism (PE) is even rarer, and there are no reports of AP complicated with PE in elderly patients.

CASE SUMMARY

We describe a rare case of AP complicated with PE and review the literature. A 68-year-old woman was diagnosed with AP due to widespread abdominal pain. During the course of treatment, the patient had shortness of breath and progressively worsening dyspnea without chest pain or hemoptysis with a progressive increase in D-dimer and fibrin degradation product. Respiratory failure and right heart failure occurred, and refractory hypoxemia remained after mechanical ventilation. Plain chest computed tomography revealed a small amount of left pleural effusion and external pressure atelectasis in the lower lobe of the left lung but no findings that could lead to refractory hypoxemia. Color Doppler ultrasound indicated pulmonary hypertension and extensive venous thrombosis in the lower extremities. Chest computed tomography angiography finally suggested pulmonary thromboembolism. The patient’s dyspnea symptoms disappeared after anticoagulation treatment.

CONCLUSION

During the diagnosis and treatment of AP, it is necessary to dynamically monitor D-dimer and consider PE.

Hyperlipidaemic acute pancreatitis complicated with multiple deep vein thromboses and pulmonary embolism: a case successfully salvaged by radiologic intervention

Acute pancreatitis complicated with pulmonary embolism has been described in literature, however, hyperlipidaemic acute pancreatitis complicated with pulmonary embolism and deep vein thrombosis has rarely been reported. We reported here a rare case of hyperlipidaemic acute pancreatitis. Although he had undergone plasmapheresis and his TG level reduced to normal range with symptoms relieved, he developed pulmonary embolism and multiple deep vein thromboses. The patient was diagnosed early and successfully salvaged by interventional radiology and oral anticoagulants. The patient was a 51-year-old man, he experienced a sudden upper abdomen pain for 24 h before being admitted to a local hospital where diagnosis of acute pancreatitis was made, and he had no relief of the symptoms after treatment. The patient was a non-smoker and did not consume alcohol. He had no history of diabetes, gallstones or cholelithasis. After transferring to our unit, the patient was treated with plasmapheresis along with low molecular weight heparin, insulin, antibiotics and proton pump inhibitors and the abdomen pain was alleviated gradually. However, 8 days after admission, the patient developed a sudden chest tightness and shortness of breath. Examination revealed a high level of D-dimer (16700 ug/L), a computer tomography angiography of chest revealed pulmonary embolism. Urokinase was started intravenously. Pulmonary angiography and venography demonstrated pulmonary embolism and extensive lower limb deep vein thrombosis. Catheter directed thrombolysis and urokinase was initiated through catheter followed by an IVC filter implantation. Dyspnea of the patient got well with thrombolytic treatment and anticoagulation therapy. This is a rare case of hyperlipidaemic acute pancreatitis complicated pulmonary embolism and Deep vein thrombosis even after treated with plasmapheresis. The case we present here will aid in its early recognition, interventional radiology hence the prevention for this rare but catastrophic complication.

Extensive Superior Vena Caval Territory Thrombosis and Pulmonary Embolism: A Rare Clinical Entity of Haemorrhagic Pancreatitis

Acute haemorrhagic pancreatitis is a severe form of pancreatitis often encountered in ethanol abuse. Extensive venous thrombosis resulting in pulmonary embolism is a rare presenting clinical entity of acute haemorrhagic pancreatitis. Here, we report a young male with an extensive deep vein thrombosis involving superior vena caval territory associated with haemorrhagic pancreatitis presented with pulmonary embolism managed supportively. Prompt recognition and appropriate intervention of this rare complication would improve the outcome in patients with acute pancreatitis.

Risk factors for and impact of respiratory failure on mortality in the early phase of acute pancreatitis

BACKGROUND

The incidence of respiratory failure and other respiratory complications in the early phase of acute pancreatitis (AP) is not well investigated.

OBJECTIVE

To evaluate the incidence and risk factors of respiratory failure, and its impact on mortality in the early phase AP.

METHODS

Retrospective cohort study including 359 patients admitted with acute pancreatitis. Information was gathered from electronic patient records. We defined respiratory failure based on the modified Marshall scoring system in the revised Atlanta criteria. Predictors of respiratory failure were evaluated in univariable and multivariable logistic regression analysis.

RESULTS

The cohort included 188 women and 171 men with a mean age of 56.1 years. Respiratory complications including pleural effusion, pneumonia and atelectasis were registered in 80 patients (22%), 100 (29%) needed oxygen therapy, 27 (8%) continuous positive airway pressure, and six (2%) mechanical ventilation. Thirty-two patients (9%) were treated with bronchodilators and 12 (3%) with steroids. Thirty-one patients (9%) fulfilled the diagnostic criteria for respiratory failure. Five of these patients (16%) did not have effusion, atelectasis or pneumonia. Predictors of respiratory failure in multivariable analysis were age (OR 1.04; CI 95% (1.03-1.07)) and smoking (OR 2.67; CI 95% (1.21-5.86)). Thirteen patients died in hospital. The Kaplan-Meier curves and log-rank tests showed that patients with respiratory failure had increased in-hospital mortality as did patients with cardiovascular and renal failure (P < 0.01 for all analyses).

CONCLUSIONS

Respiratory complications are frequent in the early phase of AP. Respiratory, cardiovascular and renal failure is associated with a poor outcome. The fact that patients without effusion, atelectasis, or pneumonia may develop respiratory failure, suggests that acute lung injury, possibly associated with systemic inflammation, may be important.

Acute pancreatitis complicated with deep vein thrombosis and pulmonary embolism: a case report

BACKGROUND

Acute pancreatitis is an acute inflammatory process of the pancreas that can trigger a systemic inflammatory response. Pulmonary embolism refers to obstruction of the pulmonary artery or one of its branches by material (usually a thrombus) that originated elsewhere in the body. Extensive lower limb deep vein thrombosis with pulmonary embolism is a rare complication of acute pancreatitis that has been described in a few case reports. Deep vein thrombosis and hypercoagulable states in pancreatitis are thought to be due to release of pancreatic proteolytic enzymes from a cyst that is connected to the pancreatic duct and penetrates into a vessel. Proteolytic damage or inflammation of the vessels may also play a significant part. Acute pancreatitis also causes a systemic inflammatory response that has effects on an endothelium-dependent relaxing response for acetylcholine.

CASE PRESENTATION

A 38-year-old Sri Lankan man presented with acute pancreatitis and later he developed progressive abdominal distention with bilateral ankle edema. A contrast-enhanced computed tomographic scan showed two pancreatic pseudocysts and deep vein thrombosis in both lower limbs, as well as a pulmonary embolism involving the right lower lobe pulmonary artery and the left segmental pulmonary arteries. One of the pseudocysts in the head of the pancreas was compressing the inferior vena cava without direct communication. The patient's thrombophilia screen result was negative. He was started on subcutaneous enoxaparin 1 mg/kg twice daily and warfarin to achieve a target international normalized ratio of 2-3.

CONCLUSIONS

Deep vein thrombosis with pulmonary embolism is a rare but life-threatening complication of acute pancreatitis. Once diagnosed, early treatment with intravenous heparin or thrombolysis is effective. Patients with severe acute pancreatitis may be at risk of deep vein thrombosis due to immobilization and other mechanisms, but anticoagulation as prophylaxis is often not used. However, it may be considered on a case-by-case basis in patients with pancreatitis who are acutely ill and immobilized, need intensive care unit admission, and have multiple risk factors for deep vein thromboembolism. Further studies must be undertaken to determine guidelines for deep vein thromboembolism prophylaxis in these patients.

Reverse-migrated neutrophils regulated by JAM-C are involved in acute pancreatitis-associated lung injury

Junctional adhesion molecule-C (JAM-C) plays a key role in the promotion of the reverse transendothelial migration (rTEM) of neutrophils, which contributes to the dissemination of systemic inflammation and to secondary organ damage. During acute pancreatitis (AP), systemic inflammatory responses lead to distant organ damage and typically result in acute lung injury (ALI). Here, we investigated the role of rTEM neutrophils in AP-associated ALI and the molecular mechanisms by which JAM-C regulates neutrophil rTEM in this disorder. In this study, rTEM neutrophils were identified in the peripheral blood both in murine model of AP and human patients with AP, which elevated with increased severity of lung injury. Pancreatic JAM-C was downregulated during murine experimental pancreatitis, whose expression levels were inversely correlated with both increased neutrophil rTEM and severity of lung injury. Knockout of JAM-C resulted in more severe lung injury and systemic inflammation. Significantly greater numbers of rTEM neutrophils were present both in the circulation and pulmonary vascular washout in JAM-C knockout mice with AP. This study demonstrates that during AP, neutrophils that are recruited to the pancreas may migrate back into the circulation and then contribute to ALI. JAM-C downregulation may contribute to AP-associated ALI via promoting neutrophil rTEM.

Ultrastructural changes in the pulmonary mechanical barriers in a rat model of severe acute pancreatitis-associated acute lung injury

This study examined the ultrastructural changes in the pulmonary mechanical barriers in a rat model of severe acute pancreatitis (SAP)-associated acute lung injury (ALI). Animals were randomized into the SAP group (n = 60) and the control group (n = 60). SAP was induced by retrograde injection of 5% taurocholic acid into the biliopancreatic duct. The morphological abnormalities assessed by histology and the lung wet/dry weight ratio and the ultrastructural abnormalities assessed by transmission electron microscope and scanning electron microscope examinations plus lanthanum nitrate tracing were compared between the two groups at 6, 12, and 24 h post-SAP induction (n = 10/group/time point). The SAP group had significantly greater extravascular effusion than the control group at each time point as assessed by the lung wet/dry weight ratio (p < .001). The severity of the tissue damage increased in the lung and pancreas over time in the SAP group (all p < .001). In the SAP group, ultrastructural damages to the endothelial, epithelial, and pleural barriers were apparent and the damages to the endothelial barrier were detected earlier than the other two barriers, suggesting its fundamental role in preventing the further development of SAP-associated ALI. Moreover, the ultrastructural abnormalities were detected earlier than symptoms and morphological changes. The ultrastructural damages in the endothelial, epithelial, and pleural barriers occurred in the early stage of SAP. The endothelial barrier is likely to be the first line to prevent the further development in this rat model of SAP-associated ALI.

In vitro evaluation of the antielastase activity of polycyclic β-lactams

A series of bi- and tricyclic β-lactam compounds was synthesized and evaluated as inhibitors of cleavage of synthetic substrates in vitro by the serine proteases Human Leukocyte Elastase (HLE), Human Leukocyte Proteinase 3 (HLPR3) and Porcine Pancreatic Elastase (PPE). The obtained results have permitted us to describe a homobenzocarbacephem compound as HLE and HLPR3 inhibitor, to observe the positive effect that the styryl group exerts on the HLE inhibitory activity in polycyclic β-lactam compounds and to conclude that the hydroxyl function decreases the HLE inhibitory activity or rules it out completely.

Pulmonary embolism with acute pancreatitis: A case report and literature review

Acute pancreatitis is an inflammatory disease characterized by local tissue injury which can trigger a systemic inflammatory response. So vascular complications of pancreatitis are a major cause of morbidity and mortality. Pulmonary embolism in acute pancreatitis has been reported to be very rare. We reported a case of pulmonary embolism with acute pancreatitis. A 38-year-old woman broke out upper abdomen pain without definite inducement. She had no nausea and vomiting, fever, dyspnea, cough and expectoration, chest pain. The patient had been diagnosed with acute pancreatitis in local hospital. The patient was treated with antibiotics and proton pump inhibitors, and the abdomen pain was alleviated slightly. But the patient came forth cough and expectoration with a little blood, progressive dyspnea. A computed tomographic scan of the abdomen revealed pancreatitis. Subsequent computer tomography angiography of chest revealed pulmonary embolism (both down pulmonary arteries, left pulmonary artery and branch of right pulmonary artery). Dyspnea of the patient got well with thrombolytic treatment and anticoagulation therapy. Pulmonary embolism is a rare but potentially lethal complication of pancreatitis. Familiarity with this complication will aid in its early diagnosis, therapy and prevent pulmonary embolism, a rare but catastrophic phenomenon.

Elastase in the prevention of arterial aging and the treatment of atherosclerosis

Arterial aging is defined as the age-related structural and functional changes in arteries from the precapillary to the aortic level. These include atheromatous changes. Such changes can be estimated in medium-sized or larger arteries by clinical diagnostic studies, including B-mode echography of the carotid artery (thickening of the intima, plaque formation and increase in luminal diameter) and abdominal aorta (plaque formation and increase in luminal diameter). Doppler echography (pulse wave velocity; PWV) and autopsy studies. These changes include distension of the lumen, increased arterial wall thickness (which may be associated with atherosclerotic plaques) and decreased extensibility of the arterial wall. Since 1981, an anti-atherosclerotic drug containing porcine pancreatic elastase 1 (PPE1) has been used for the prevention of arterial aging and the treatment of atherosclerosis in elderly patients in Japan. So far, the age-related increase in PWV has been found to be lower in those who take PPE1 than in controls. The atherosclerotic index of the carotid artery has also been found to be lower in subjects receiving PPE1 treatment than in control subjects. The pharmacological basis of PPE1 therapy, although paradoxical to the consensus opinion of the pathogenic role of elastase in western countries, is discussed with reference to data gathered in Japan. The pathomechanism of arterial aging and atherosclerosis, with special reference to elastin, is reviewed along with the presentation of some of our data.

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.

Neutral Endopeptidase Determines the Severity of Pancreatitis-Associated Lung Injury1

BACKGROUND

Neutral endopeptidase (NEP) is a cell-surface metalloprotease that degrades proinflammatory peptides such as substance P, neurokinin A, and bradykinin. Inhibition of NEP exacerbates both experimental pancreatitis and the associated lung injury. It is unclear if worsened lung injury is the indirect result of more severe pancreatitis or if it is a direct effect of NEP inhibition in the lung.

MATERIALS AND METHODS

We used a model of pancreatitis-associated lung injury (PALI) to test the hypothesis that antagonism or genetic deletion of NEP augments PALI inflammation and pulmonary damage irregardless of the degree of pancreatitic inflammation.

RESULTS

In NEP(+/+) mice, intraperitoneal injection of porcine pancreatic elastase (elastase, 0.085 U/g at t = 0 h and t = 1 h) caused a 7-fold increase in lung myeloperoxidase (MPO) activity and marked pulmonary edema, neutrophil infiltration, and hemorrhage at 4 h as compared to control animals. The pattern of lung injury induced by elastase mimicked that observed among a separate group of animals with PALI induced by cerulein but was not associated with pancreatitis. Both NEP(-/-) mice and NEP(+/+) mice pretreated with the NEP antagonist phosphoramidon (10 mg/kg s.c.) had significant elevations of lung MPO and worsened lung histology compared to NEP(+/+) mice given elastase alone. Antagonism of either the vanilloid receptor transient receptor vanilloid 1 or the substance P receptor NK1-R had no effect on elastase-mediated lung injury in NEP-deficient mice.

CONCLUSIONS

NEP is an inhibitor of pancreatic elastase-induced lung injury, presumably via degradation of proinflammatory mediators.

Nutrition support during acute pancreatitis

Studies have shown that protein catabolism increases by 80% and energy expenditure by 20% in acute pancreatitis, indicating that nutritional requirements are elevated. Other studies have associated the resolution of negative nitrogen balance by nutrition support with improved outcome. Consequently, the need for effective nutrition is one cornerstone of management of acute pancreatitis. Concerns that feeding may exacerbate the disease process by stimulating the synthesis of proteolytic enzymes in the acinar cell and perpetuating autolysis has led to the widespread use of total parenteral nutrition (TPN) and bowel rest. Unfortunately, the use of TPN in clinical practice has been associated with major metabolic and infective complications, possibly because 1). patients with acute pancreatitis are intolerant of glucose due to coexistent pancreatic endocrine dysfunction and 2). the disease causes immune suppression. This has led to the search for alternatives. Based on physiologic studies, infusion of nutrients into the distal jejunum bypasses the stimulatory effect of feeding on pancreatic secretion. Many controlled trials have compared TPN with jejunal feeding. No study has shown that jejunal feeding exacerbates the disease. Further, jejunal feeding is associated with fewer infectious and metabolic complications. These observations and the fact that enteral feeding is one-tenth the cost of TPN has resulted in the general acceptance of jejunal feeding as the preferred mode for maintaining nutrition in patients with acute pancreatitis.

Trypsin and activation of circulating trypsinogen contribute to pancreatitis-associated lung injury

Pancreatic proteases are secreted in acute pancreatitis, but their contribution to associated lung injury is unclear. Applying models of mild edematous (intravenous caerulein) and severe necrotizing (intraductal glycodeoxycholic acid) pancreatitis in rats, we showed that both trypsinogen and trypsin concentrations in peripheral blood, as well as lung injury, correlate with the severity of the disease. To isolate the potential contribution of proteases to lung injury, trypsin or trypsinogen was injected into healthy rats or trypsinogen secreted in caerulein pancreatitis was activated by intravenous enterokinase. Pulmonary injury induced by protease infusions was dose dependent and was ameliorated by neutrophil depletion. Trypsinogen activation worsened lung injury in mild pancreatitis. In vitro incubation of leukocytes with trypsinogen showed that stimulated leukocytes can convert trypsinogen to trypsin. In conclusion, this study demonstrates that the occurrence and severity of pancreatitis-associated lung injury (PALI) corresponds to the levels of circulating trypsinogen and its activation to trypsin. Neutrophils are involved in both protease activation and development of pulmonary injury.

Proteases and protease inhibitors in cerulein-induced acute pancreatitis in rats

BACKGROUND

Proteases and protease inhibitors are important in acute pancreatitis (AP), although little is known about the time course in cerulein-induced AP in the rat.

MATERIALS AND METHODS

AP was induced by supramaximal stimulation of cerulein, 10 microgram/kg/h, and during 72 h we measured lipase, amylase, albumin, prekallikrein, factor X, alpha(1)-protease inhibitor, alpha(1)-macroglobulin, alpha(2)-antiplasmin, antithrombin III (all in plasma) and macroscopic and histologic variables.

RESULTS

Within 12 h an edematous pancreatitis was evident with peak values of peritoneal exudate, pancreatic wet weight ratio, and plasma amylase and lipase activities. Histologically, edema and vacuolization were prominent already after 3 and 6 h, respectively, while inflammation, necrosis, and total histological score gradually increase to reach peak levels at 48 h. Proenzymes and most plasma protease inhibitors decreased to low levels after 6-12 h followed by a gradual increase. The sequential changes over time indicate that kallikrein - kinin activation, and plasminogen activation are probably early events in cerulein-induced AP in rats. alpha(1)-Macroglobulin and alpha(1)-protease inhibitor gradually decreased during the whole study period, probably being "second line" defense inhibitors. Levels above normal were seen for alpha(2)-antiplasmin and factor X at 48 h, normalizing at 72 h.

CONCLUSIONS

These results suggest that protease activation and protease inhibitor consumption occur in cerulein-induced AP in the rat.

Pancreatic enzyme-induced pancreatitis and systemic complications in rats

Effects of retrograde injection into the pancreatic duct and intravenous infusion of pancreatic enzymes and bile salt on the pancreas and other vital organs such as the liver and the lung were investigated in rats. Intraductal injection (1 ml/kg) of alpha-chymotrypsin (50-100 mg/ml), trypsin (10-100 mg/ml), pancreatic elastase (10 mg/ml), lipase (100-300 mg/ml), pancreatic kallikrein (25 mg/ml) and sodium taurocholate (50 mg/ml) solutions significantly increased pancreatic water content. Alpha-chymotrypsin, pancreatic elastase, taurocholate and trypsin elicited gross pancreatic hemorrhage. In contrast, lipase and kallikrein elicited gross pancreatic edema, but not hemorrhage. Intravenous infusion of trypsin (1 mg/kg/hr) and pancreatic elastase (10 mg/kg/hr) significantly increased pulmonary vascular permeability in rats, whereas infusion of neutrophil elastase (0.3 mg/kg/hr) did not elicit these effects. Only trypsin slightly reduced arterial oxygen pressure. These results show pancreatic enzymes and bile salts induce pancreatic inflammation after retrograde injection into the pancreatic duct in rats. Furthermore, trypsin and pancreatic elastase extravasation into the vascular system can lead to pulmonary dysfunction in rats.

Protective effect of a pancreatic elastase inhibitor against a variety of acute pancreatitis in rats

Protective effect of trifluoroacetyl-L-lysyl-L-alaninanilide hydrochloride (compound 1), a pancreatic elastase inhibitor, on three types of acute pancreatitis models was examined in rats. Mild, moderate and severe acute pancreatitis were induced by cerulein, the closed duodenal loop method and retrograde injection of a taurocholate plus trypsin solution into the pancreatic duct, respectively. Intravenous infusion of compound 1 at a dose of 30 mg/kg/hr resulted in lower increases in serum amylase, lipase, blood urea nitrogen (BUN) and creatinine levels in rats with mild cerulein-induced edematous pancreatitis. Compound 1 had no beneficial effect on pancreatitis in rats with moderate pancreatitis. In rats with severe pancreatitis, prophylactic treatment of compound 1 (30 mg/kg/hr) reduced both elevated serum BUN level and ascitic volume, and it histologically inhibited the extent of pancreatic edema and hemorrhage. These results suggest that pancreatic elastase is partially responsible for pancreatic edema and hemorrhage exhibited by rats with severe acute pancreatitis.

Neutrophil elastase inhibitor (ONO-5046) prevents lung hemorrhage induced by lipopolysaccharide in rat model of cerulein pancreatitis

The protective effects of a neutrophil elastase inhibitor (ONO-5046) on cerulein-induced pancreatitis followed by a septic challenge with intraperitoneal lipopolysaccharide (LPS) were studied in a rat model. Pancreatitis was induced by four intramuscular injections of cerulein (50 micrograms/kg at 1-hr intervals). ONO-5046 was administered by continuous intravenous infusion via the right jugular vein (50 mg/kg/hr, 30 min prior to the first cerulein injection to 20 hr following the last cerulein injection). Significant differences in serum amylase and pancreatic wet weight ratio were not observed between the animals with pancreatitis treated with or without ONO-5046. There was no significant difference in the in vitro tumor necrosis factor-alpha (TNF-alpha) production by peritoneal macrophages from rats with pancreatitis treated with or without ONO-5046. In a second experiment, LPS (10 mg/kg) was administered intraperitoneally as the septic challenge 6 hr following the first cerulein injection. Lung hemorrhage was seen in the animals with pancreatitis untreated with ONO-5046 24 hr following the first cerulein injection. No significant lung hemorrhage was observed in the animals with pancreatitis treated with ONO-5046 administering 30 min prior to the first cerulein injection. These results suggest that lung hemorrhage in cerulein-induced pancreatitis that follows a septic challenge with LPS can be prevented by the intravenous administration of ONO-5046. Thus there is a significant role for neutrophil elastase in pancreatitis-associated lung injury.

Interleukin-1 receptor antagonist modifies the changes in vital organs induced by acute necrotizing pancreatitis in a rat experimental model

OBJECTIVE

Interleukin-1 (IL-1) is a mediator in some critical conditions such as septic shock and multiple organ failure. Acute pancreatitis is one of the noted causes of multiple organ failure but the mechanism by which local inflammation progresses to systemic disease is unknown. In this study, we used an IL-1 receptor antagonist (IL-1ra) to investigate whether multiple organ failure due to acute pancreatitis is mediated by IL-1, as in other causes such as severe infection, trauma, and major surgery.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Research laboratory of a university medical school.

SUBJECTS

Specific pathogen-free male Wistar rats weighing 200 to 250 g.

INTERVENTIONS

Necrotizing pancreatitis was induced by retrograde injection of deoxycholate solution into the biliopancreatic duct. IL-1ra was injected intravenously at a dose of 10 mg/kg 15 mins before induction of acute pancreatitis and then infused continuously at a rate of 5 mg/kg/hr for the following 24 hrs.

MEASUREMENTS AND MAIN RESULTS

Although treatment with recombinant human IL-1ra did not affect the degree of local pancreatic insult, it significantly reduced mortality, improved urine output as an indicator of the state of shock, and ameliorated the accumulation of neutrophils into the lung in a rat experimental pancreatitis model.

CONCLUSIONS

We concluded that multiple organ failure in severe pancreatitis is mediated, at least in part, by IL-1 through the activation of neutrophils. Furthermore, we concluded that circulatory collapse may also be important in the mechanism of the lethal effect of pancreatitis.

Hemodynamic effects following intraperitoneal infusion of pancreatic ascites fluid

Severe necrotizing pancreatitis is accompanied by release of hemorrhagic ascites fluid (HAF), which is thought to be related to the occurrence and frequency of cardiocirculatory and pulmonary failure as a consequence of acute pancreatitis. The purpose of this study was to evaluate the role of HAF due to these systemic complications. Experiments were performed in 25 pigs (mean b.wt. 22 +/- 1 kg) under general anesthesia and mechanical ventilation. The animals received 50 ml/kg b.wt. i.p. of either physiologic saline solution (control CO, n = 9) or hemorrhagic ascites fluid (HAF, n = 16). HAF was obtained from 16 pigs with pancreatitis induced by intraductal infusion of bile salt. Eight animals in the HAF group were pretreated with indomethacin (10 mg/kg i.v. INDO/HAF). All animals were followed up for 6 h. Mean arterial pressure, cardiac output, and stroke volume fell significantly in the HAF (-25%, -27%, -27%) and in the INDO/HAF groups (-24%, -20%, -17%) as compared with controls (-6%, -6%, -6%). Also, left ventricular end-diastolic pressure (LVEDP) decreased by 52% and 48% in both HAF recipient groups, whereas LVEDP was unchanged in the control group. Myocardial contractility (Vmax) remained unaltered in all experimental groups. No significant differences in gas exchange and lung dry/wet weight ratio were observed. Lipase and PGI2 of the unpretreated HAF group rised to 203% and 198% in arterial blood at 6 h compared with unaltered levels in the control group. No increase of prostanoid concentrations was detected in the indomethacin-pretreated group, whereas lipase increase by a comparable extent as in the HAF group. We conclude that the early consequences of HAF are mainly characterized by systemic hypotension due to hypovolemia.

Lung injury in acute experimental pancreatitis in rats. I. Morphological studies

The pathogenesis of pancreatitis-related pulmonary injury was studied at the light- and electronmicroscopic level. Experimental pancreatitis was induced in rats by infusion of supramaximal doses of cerulein for 12 h. Investigations were carried out 3, 6, and 12 h after the start of infusion and 12, 48, and 72 h after the end of pancreatitis induction. Initial manifestations of pancreatitis-associated lung injury revealed a pronounced clustering of polymorphonuclear leukocytes in pulmonary microvessels, followed by severe damage of alveolar endothelial cells. Consecutively, the increase in vascular permeability of the lung resulted in interstitial edema formation. Structural changes were maximal after 12 h and reversed completely after 84 h. In conclusion, the structural appearance of pulmonary injury in cerulein-induced pancreatitis was similar to that reported in early stages of the adult respiratory distress syndrome (ARDS). It is suggested that polymorphonuclear granulocytes play a crucial role in the pathogenesis of pancreatitis-related lung injury.

Kinetics of the inhibition of human pancreatic elastase by recombinant eglin c. Influence of elastin

Recombinant eglin c is a potent reversible inhibitor of human pancreatic elastase. At pH 7.4 and 25 degrees C, kass. = 7.3 x 10(5) M-1.s-1, kdiss. = 2.7 x 10(-4) s-1 and Ki = 3.7 x 10(-10) M. Stopped-flow kinetic indicate that the formation of the stable enzyme-inhibitor complex is not preceded by a fast pre-equilibrium complex or that the latter has a dissociation constant greater than 0.3 microM. The elastase-eglin c complex is much less stable at pH 5.0 and 25 degrees C, where kdiss. = 1.1 x 10(-2) s-1 and Ki = 7.3 x 10(-8) M. At pH 7.4 the activation energy for kass. is 43.9 kJ.mol-1 (10.5 kcal.mol-1). The kass. increases between pH 5.0 and 8.0 and remains essentially constant up to pH 9.0. This pH-dependence could not be described by a simple ionization curve. Both alpha 2-macroglobulin and alpha 1-proteinase inhibitor are able to dissociate the elastase-eglin c complex, as evidenced by measurement of the enzymic activity of alpha 2-macroglobulin-bound elastase or by polyacrylamide-gel electrophoresis of mixtures of alpha 1-proteinase inhibitor and elastase-eglin c complex. The rough estimate of kdiss. obtained with the alpha 2-macroglobulin dissociation experiment (1.6 x 10(-4) s-1) was of the same order of magnitude as the constant measured with the progress curve method. Eglin c strongly inhibits the solubilization of human aorta elastin by human pancreatic elastase. The extent of inhibition is the same whether elastase is added to a suspension of elastin and eglin c or whether elastase is preincubated with elastin for 3 min before addition of eglin c. However, the efficiency of the inhibitor sharply decreases if elastase is reacted with elastin for more prolonged periods.

[Acute necrotizing hemorrhagic pancreatitis]

There is no etiologic treatment for acute necrotizing pancreatitis. Advances in intensive care resulted in a reduction in early death rate by a better control of systemic complications. Delayed death rate from infection is high (20-60%). Diagnostic problems are an important cause, in spite of the aid of computed tomography and echography. The prognosis will further be improved by earlier diagnosis, a better definition of surgical treatment when complications arise, and constant medicosurgical collaboration.

Crystal structures of the complex of porcine pancreatic elastase with two valine-derived benzoxazinone inhibitors

The crystal structures of porcine pancreatic elastase complexed to two similar benzoxazinone inhibitors are reported to 2.09 A and 1.76 A resolution, and refined to conventional R factors of 0.153 and 0.172.

Purification and partial characterization of elastase activity from rat alveolar and peritoneal macrophages

Macrophage elastase was purified from conditioned media from alveolar and thioglycollate-elicited peritoneal macrophages. The enzyme was purified to apparent electrophoretic homogeneity by preparative isoelectric focusing after a purification step consisting of low ionic strength dialysis and sequential batch fractionation on DEAE-Sephadex A-50. The proteinase activities isolated from alveolar and peritoneal macrophages showed the same physical and biochemical properties. This fact suggests that the same enzyme activity is present in rat macrophages of two different anatomical sites. The molecular weight and isoelectric point of the enzyme were estimated to be 22,500 and 8.3, respectively. The enzyme, characterized as a metallo proteinase, had elastolytic activity, as well as activity toward Suc-(Ala)3-NA. It is inhibited by o-phenanthroline, chicken ovoinhibitor, and EDTA, but not by phenylmethylsulfonyl fluoride or soybean trypsin inhibitor. The macrophage enzyme possesses biochemical and biophysical properties different from the rat pancreatic and granulocyte elastases (which are serine proteinases), and from the metallo proteinase with elastolytic activity isolated from rat platelets.

Isolation and partial characterization of rat elastolytic enzymes from various cells and tissues

Different elastolytic enzymes were isolated from rat aorta and platelets, as well as from granulocyte and pancreatic extracts. The active fractions were purified to electrophoretic apparent homogeneity by precipitation with ammonium sulfate, sequential batch fractionation on DEAE-Sephadex A-50, and finally by isoelectric focusing (IF) on Sephadex G-75 Superfine. The molecular weight and the isoelectric point of the isolated enzymes were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and by analytical IF, respectively. All the enzymes have elastolytic activity as well as activity toward Suc-(Ala)3-NA. The inhibition profile of the different isolated enzymes toward various inhibitors indicates that aortic, pancreatic, and granulocyte enzymes all belong to the group of serine proteinases, unlike the platelet elastase which is a metalloproteinase.

The lung lysosomal hydrolases and phospholipase A in acute experimental pancreatitis with reference to heparin treatment

The pulmonary complications are severe sequeles of acute pancreatitis. The pathogenesis of these complications is unsolved. The purpose of this work was to evaluate the status of lung lysosomes and phospholipase A activity in acute experimental pancreatitis (AEP) and the effect of heparin as a potentially protective agent. Taurocholate-induced AEP in rats lasting 24 and 48 hours was treated with heparin intraperitoneally (2 mg/kg every 8 hours). The total activity of cathepsins and B-glucuronidase in lysosomal enriched subfraction increased markedly during 48 hours of AEP in untreated animals, but the relative free activity was maximal after 24 hours. Free activity of cathepsins and acid phosphatase in supernatant was maximal after 24 hours. The phospholipase A activity was maximally elevated (more than twofold) after 48 hours. Heparin prevented the increase of activity of B-glucuronidase, depressed the relative free activity of all investigated lysosomal hydrolases and inhibited the phospholipase A activity in the lung homogenate. Our results indicate the significance of labilization of lung lysosomes and increment of phospholipase A activity in the lungs in the damage of this organ during AEP in the rats, and suggest the beneficial effect of heparin on these factors.

Elastase effect on the extracellular matrix of rat aortic smooth muscle cells in culture

The effect of elastase on the extracellular matrix of neonatal rat aortic smooth muscle cell cultures was monitored both chemically and ultrastructurally. Porcine pancreatic elastase was shown to decrease the elastin content in these cultures. Although chemically no distinction could be made between the elastin remaining in the culture matrix after elastase when compared to that in the nontreated cultures, the elastin was dramatically altered morphologically. The elastin assumed a "mottled" appearance after elastase treatment similar to that seen in vivo in emphysema models. A highly sensitive immunogold staining technique was used to detect elastin at the earliest stages of accumulation. Pulse experiments demonstrated an increase in protein synthesis by the cells 20 hr after elastase exposure. The culture system described here provides a model for probing in vivo elastase effects on elastin-containing tissues.

Stereochemistry of binding of the tetrapeptide acetyl-Pro-Ala-Pro-Tyr-NH2 to porcine pancreatic elastase. Combined use of two-dimensional transferred nuclear Overhauser enhancement measurements, restrained molecular dynamics, X-ray crystallography and molecular modelling

A nuclear magnetic resonance study of the conformation of the tetrapeptide acetyl-Pro-Ala-Pro-Tyr-NH2 bound to porcine pancreatic elastase is presented. From two-dimensional transferred nuclear Overhauser enhancement measurements, a set of 23 approximate distance restraints between pairs of bound ligand protons, indicative of an extended type structure, is derived. The structure of the bound tetrapeptide is then refined from two different starting structures (an extended beta-strand and a polyproline helix) by restrained molecular dynamics, in which the interproton distances are incorporated into the total energy of the system in the form of effective potentials. Convergence to essentially the same average restrained dynamics structures is achieved. The refined structures are then modelled into the active site of elastase by interactive molecular graphics. The determination of the anchor point of the bound tetrapeptide on the enzyme was aided by a simultaneous crystallographic study which, despite the fact that only electron density for a Pro-X dipeptide fragment was visible, enabled both the approximate position and orientation of binding to be determined. It is found that the tetrapeptide is bound in the S' binding site in the reverse orientation found in other serine protease-inhibitor complexes and is stabilized both by hydrogen-bonding and by van der Waals' interactions.

Structure of the product complex of acetyl-Ala-Pro-Ala with porcine pancreatic elastase at 1.65 A resolution

A single crystal of porcine pancreatic elastase was mounted in a thin-walled capillary and allowed to react with acetyl-Ala-Pro-Ala-paranitroanalide. Diffraction data to 1.65 A resolution were measured and the isomorphous structure was solved from the difference Fourier map. The structure contains two surprises. Two molecules of the product: acetyl-Ala-Pro-Ala molecule are bound in the extended binding site. Both molecules are bound backwards with respect to the established mode of peptide binding.