ONO-1714, a nitric oxide synthase inhibitor, attenuates endotoxin-induced acute lung injury in rabbits

Overproduction of nitric oxide by inducible nitric oxide synthase (iNOS) expressed in the lung is thought to play a crucial role in the pathogenesis of endotoxin-induced acute lung injury (ALI). In this two-part study, we determined whether ONO-1714, a new selective iNOS inhibitor, attenuates endotoxin-induced ALI in rabbits. For Part I of the study, a control group received IV saline and ALI was induced by IV infusion of endotoxin 5 mg/kg over 30 min in 4 groups. Three groups received either 0.1, 0.03, or 0.01 mg/kg of ONO-1714 10 min before the start of endotoxin and the fourth group received saline. For Part II of the study, ALI was induced by endotoxin infusion in all 6 groups. One group was treated with saline. The other 5 groups received ONO-1714 0.1 mg/kg at various timings (10 min before or 1, 2, 3, or 4 h after ALI induction). The lungs were mechanically ventilated with 40% oxygen for 6 h after induction of ALI. In Part I, pretreatment with 0.1 mg/kg ONO-1714 mitigated endotoxin-induced ALI. In Part II, early posttreatment (within 2 h after the insult) with ONO-1714 was as effective as pretreatment in improving oxygenation, lung mechanics, lung leukosequestration, pulmonary edema, and histological change. However, lung damage was not improved in rabbits receiving the drug 3 or 4 h after endotoxin. These data suggest that the current study is a basis for future clinical trials to elucidate whether ONO-1714 can be a promising therapeutic approach in patients with acute respiratory distress syndrome induced by endotoxin/sepsis. IMPLICATIONS: An excess of nitric oxide is thought to play a crucial role in the pathogenesis of acute organ injury in endotoxemia. Early posttreatment with ONO-1714, a nitric oxide synthase inhibitor, attenuated physiological, biochemical, and pathological changes in endotoxin-induced acute lung injury in rabbits.     

Effect of a neutrophil elastase inhibitor (ONO-5046 Na) on ischemia/reperfusion injury using the left-sided heterotopic canine heart transplantation model.

BACKGROUND: Ischemia/reperfusion injury is a major cause of transplanted heart dysfunction. Several reports have demonstrated that polymorphonuclear neutrophil (PMN) elastase derived from the activated neutrophils might play an important role in this injury. Herein, we investigated the protective effects of PMN elastase inhibitor (ONO-5046 Na) on ischemia/reperfusion injury using a left-sided canine heterotopic heart transplantation model. METHODS: We used 10 pairs of adult beagle dogs. The donor heart was transplanted heterotopically into the left thoracic cavity of the recipient without cardiopulmonary bypass. A bolus of ONO-5046 Na (10 mg/kg) was introduced intravenously to 5 recipients (group II) at 15 minutes before reperfusion and was followed by continuous infusion (10 mg/kg per hour) for 180 minutes. Five dogs (group I) did not receive ONO-5046 Na and thus served as a control. After reperfusion, we evaluated transplanted heart function and obtained blood samples from the coronary sinus over a 360-minute period. RESULTS: E(max) and pre-load recruitable stroke work in group II showed significantly better recovery than group I. Blood levels of PMN elastase, creatine kinase MB, lactate and inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, interleukin-8) were significantly lower in group II. Depletion of myocardial concentration of adenosine triphosphate at 120 minutes after reperfusion and myocardial water content was significantly lower in group II. CONCLUSIONS: ONO-5046 Na, which inhibits PMN elastase, could reduce ischemia/reperfusion injury in heart transplantation. These results indicate that clinical application of ONO-5046 Na should be considered.     

Neutrophil Elastase Inhibitor, ONO-5046, Modulates Acid-induced Lung and Systemic Injury in Rabbits

Background: Acid instillation leads to direct lung and to secondary systemic organ injury, probably via activated macrophages and neutrophils. This study investigated the effects of neutrophil elastase on organ injury after unilateral lung acid instillation by administrating a specific neutrophil elastase inhibitor, ONO-5046, before acid instillation.

Methods: Three groups of anesthetized rabbits (n = 12 in each group) underwent tracheostomies, and instillations were made into their right lower lobe airspaces with either phosphate buffered saline (pH, 7.4; volume, 1.2 ml/kg; n = 12) or HCl (pH, 1.25; volume, 1.2 ml/kg; n = 24). In half of the acid-instilled rabbits, ONO-5046,10 mg/kg, was given intravenously 15 min before the HCl instillation, and then 10 mg [center dot] kg sup -1 [center dot] h sup -1 of the drug was continuously infused throughout the experiment. The other groups of animals received the vehicle intravenously. Anesthesia and mechanical ventilation was continued for 8 h, whereas arterial blood gases were sampled intermittently. Eight hours after saline or acid instillation, the animals were killed, and their lungs, heart, kidneys, liver, and small intestines were harvested. Wet-to-dry weight ratios (W/D) and myeloperoxidase (MPO) assays of these organs were done, and elastase assays on the bronchoalveolar lavage fluids (BALF) obtained from each lung also were performed.

Results: Pretreatment with ONO-5046 attenuated the physiologic changes seen in the vehicle-treated animals. Significant decreases in W/D of the noninstilled lungs and of the small intestine and normalization of the oxygenation of the experimental animals occurred. The ONO-5046 pretreatment did not affect the neutrophil sequestration in the lungs or in the other organs as determined by neutrophil counts in BALF and by the MPO assays.     

The effects of a specific neutrophil elastase inhibitor (ONO-5046) in pulmonary ischemia–reperfusion injury

Ischemia-reperfusion injury is a significant problem in lung transplantation. Polymorphonuclear elastase derived from neutrophils plays a major mechanistic role in this process. Hence, we have investigated the effects of ONO-5046, a neutrophil elastase inhibitor, on ischemia-reperfusion injury. Fifteen rabbits were divided into three groups: 2 h of single left-lung perfusion (control group, n=3); 2 h of ischemia followed by 2 h of reperfusion (ischemic group, n=6); and drip intravenous administration of ONO-5046 during the 2 h of ischemia and 2 h of reperfusion (ONO-5046 group, n=6). Hemodynamic parameters were determined and a histopathological examination of the lung was performed. In the ONO-5046 group, arterial oxygen pressure, cardiac output, and tissue blood perfusion were higher and pulmonary vascular resistance was lower than in the ischemic group. The ONO-5046 group also showed large decreases in neutrophil infiltration, pulmonary edema, and intra-alveolar hemorrhage. Treatment with ONO-5046 improves lung function in a rabbit-lung ischemia-reperfusion model.     

Neutrophil elastase and oxygen radicals enhance monocyte chemoattractant protein- expression after ischemia/reperfusion in rat liver

BACKGROUND: The monocyte chemoattractant protein-1 (MCP-1) is produced during reperfusion injury and induces tissue factor that is the initiator of the clotting cascade. Neutrophil elastase is a crucial mediator of inflammatory tissue damage. Activation of the coagulation system stimulates cytokine production by activated leukocytes. We investigated the effects of neutrophil elastase and oxygen radicals generated by hypoxia associated with microthrombus formation on MCP-1 expression after ischemia/reperfusion in rat liver. METHODS: In vitro MCP-1 production by macrophages after stimulation with human neutrophil elastase (HNE) or oxygen radicals generated by hypoxanthine and xanthine oxidase was examined. Liver ischemia was induced in rats by occluding the portal vein for 30 min. An inhibitor of human neutrophil elastase (ONO-5046*Na, 10 mg/kg) and antithrombin III (AT-III, 250 U/kg) were injected i.v. 5 min before vascular clamping. Serum concentrations of MCP-1 were measured by enzyme-linked immunosorbent assay. RESULTS: Human neutrophil elastase or oxygen radicals significantly enhanced in vitro MCP-1 production by macrophage. Serum MCP-1 concentrations reached a peak at 6 hr after reperfusion and then gradually decreased. However, pretreatment of animals with AT-III or ONO-5046*Na alone resulted in significantly smaller increases in serum concentrations of MCP-1 after reperfusion. Pretreatment with both ONO-5046*Na and AT-III produced additive effects. The combined treatment with ONO-5046*Na and AT-III significantly reduced MCP-1 mRNA in liver after ischemia/reperfusion. CONCLUSIONS: MCP-1 production by macrophages is stimulated by neutrophil elastase and oxygen radicals generated by hypoxia, probably due to microthrombus formation after ischemia/reperfusion of the rat liver.     

Protective effects of ONO-5046*Na, a specific neutrophil elastase inhibitor, on postperfusion lung injury

Background. Polymorphonuclear neutrophil elastase might contribute to postperfusion lung injury, so we evaluated the protective effect of ONO-5046·Na, a specific inhibitor of polymorphonuclear neutrophil elastase, against such an injury.

Methods. The study was done using 8 mongrel dogs that received ONO-5046·Na (15 mg/kg per hour) (group O) and 8 control dogs (group C), all of which had 1 hour of partial bypass and 5 hours of observation.

Results. The respiratory index showed no significant changes in group O, but increased significant in group C (1.4 ± 2.0 versus 5.1 ± 4.7, p = 0.0047). Pulmonary extravascular water volume increased markedly in group C but only slightly in group O (group C 20.6 ± 8.7, group O 11.2 ± 2.7 mL/kg; p = 0.0005). Blood concentrations of polymorphonuclear neutrophil elastase and interleukin-6 showed more than a tenfold increase in group C (PMN elastase, group C 12.9 ± 12.8, group O 2.4 ± 1.3 ng/mL; IL-b, group C 11.0 ± 9.3, group O 2.9 ± 3.8 pg/mL; p < 0.05) but were only slightly higher in group O. Histologic examination revealed interstitial and intraalveolar edema in group C, but group O was virtually normal.

Conclusions. ONO-5046·Na inhibits polymorphonuclear neutrophil elastase and maintains better pulmonary function, so it should reduce postperfusion lung injury.     

Pretreatment of acid-induced lung injury with specific neutrophil elastase inhibitor ONO-5046 did not exasperate the subsequent bacterial lung infection by Pseudomonas aeruginosa

Patients with acid lung injuries are at high risk for bacterial pulmonary infections which commonly occur several days after the acid aspiration. We reported that a specific neutrophil elastase inhibitor ONO-5046 inhibited the multi-organ injury caused by acid-instillation into the lung. In this study, we evaluated the effect of ONO-5046 on lung infection by Pseudomonas aeruginosa (PAO-1:Ps.) following acid-induced lung injury in rat lungs. Animals received 0.2 ml of hydrochloric acid (pH = 1) into the right lungs. Pretreated animals were administered ONO-5046 (30 mg.kg-1) i.v. 15 min. before acid instillation. Other groups received vehicle (saline). Twenty four hours later, they were instilled with 0.1 ml of Ps. 1 x 10(8) cfu into the left lungs. Four hours after bacterial challenge, the animals were deeply anesthetized and killed. Bronchoalveolar lavage was done on each lung separately to evaluate neutrophil elastase activity, neutrophil number and protein permeability of lung endothelium and epithelium. The numbers of Ps. in the lungs were measured. In the Ps.-instilled lung, the number of Ps. or the protein permeability was not increased with ONO-5046 pretreatment compared with those in the untreated group. Pretreatment inhibited the exasperation of the protein permeability indirectly caused by Ps. infection in the acid-instilled lung. It was indicated that ONO-5046 could inhibit the indirect lung injury caused by acid-instillation into the lung without aggravating the subsequent bacterial infection.     

Neutrophil elastase inhibitor ameliorates reperfusion injury in a canine model of lung transplantation

BACKGROUND: We investigated the effects of neutrophil elastase inhibitor ONO-5046 Na on lung ischemia-reperfusion injury in a canine model of single lung transplantation. METHODS: 24 mongrel dogs, 12 donors and 12 recipients, were used for single lung transplantation. Lung grafts were preserved for 18 h by cold ischemia then transplanted into the left thoracic cavity of recipients. In 6 recipients (ONO group), a bolus of ONO-5046 Na (10 mg/kg) was introduced before reperfusion and followed by continuous infusion (10 mg/kg/h). The remaining 6 recipients (control group) did not receive ONO-5046 Na and thus served as controls. We evaluated lung function and respiratory parameters over 240 min. RESULTS: The total cell number in bronchoalveolar lavage fluid increased significantly in the control group in comparison to that in the ONO group. Histologic scores after 4 h of reperfusion and myeloperoxidase activity were significantly lower in the ONO group than in the control group. CONCLUSION: Neutrophil elastase inhibitor ONO-5046 Na may be useful in ameliorating lung reperfusion injury after transplantation.     

Benefical effect of neutrophil elastase inhibitor on renal warm ischemia-reperfusion injury in the rat

Renal ischemia-reperfusion (I/R) injury is a significant problem in renal transplantation. Neutrophils play an important role in renal I/R injury. Several reports have demonstrated that neutrophil elastase derived from the activated neutrophils might play an important role in this injury. We investigated the effect of a neutrophil elastase inhibitor in renal I/R injury. Male Lewis rats (270-320 g) were used in the model. The right kidney was harvested and the left renal artery and vein were clamped at laparotomy. The kidney was reperfused after 90 minutes of ischemia. Neutrophil elastase inhibitor (ONO-5046: 30 mg/kg) was delivered intravenously before ischemia and after reperfusion to prevent neutrophil activation. In the nontreatment I/R group, no hosts survived 4 days. However, after treatment with neutrophil elastase inhibitor, 3 of 10 rats in the I/R group, survived more than 7 days. These results demonstrated that treatment with neutrophil elastase inhibitor ameliorated renal I/R injury.     

Neutrophil elastase inhibitor reduces hepatic metastases induced by ischaemia-reperfusion in rats.

OBJECTIVE: To investigate the possibility in rats that ONO-5046 Na, a new recombinant inhibitor of neutrophil elastase, can reduce hepatic metastases induced by ischaemia-reperfusion. DESIGN: Laboratory experimental study. SETTING: Research laboratory, Japan. SUBJECTS: Male Fischer rats. INTERVENTIONS: Rats underwent 60 min of 70% partial hepatic ischaemia, after which rat colon adenocarcinoma cells (RCN-H4) were injected into the spleen. The animals were divided into two test groups and a control group. One group was given ONO-5046 Na intravenously at 10 mg/kg/hour. A second group was given a saline solution for the same period, while the controls were not made ischaemic. MAIN OUTCOME MEASURES: Three weeks after inoculation, the number of tumour nodules on the liver surface was counted. The anti-cancer effect of ONO-5046 Na was measured by monotetrazolium assay. RESULTS: Hepatic ischaemia-reperfusion increased the number of liver metastases of RCN-H4 in both clamped and unclamped hepatic lobes. ONO-5046 Na significantly inhibited this in unclamped lobes, but had no anti-cancer effect. CONCLUSION: Neutrophil elastase may have an important role in increasing haematogenous liver metastases by ischaemia-reperfusion, particularly in unclamped lobes.     

Effect of specific neutrophil elastase inhibitor on ischemia/reperfusion injury in rat liver transplantation.

Activated neutrophils have been implicated as playing an important role in ischemia/reperfusion injury of the liver by releasing toxic mediators such as oxygen free radicals and elastases. In the present study, we evaluated the effect of a novel, specific neutrophil elastase inhibitor (ONO-5046) on cold-ischemia/reperfusion injury of the liver allograft in rodents. Livers from male Lewis rats were procured and stored cold (4 degrees C) in lactated Ringer's solution and transplanted orthotopically. Recipients were divided into three groups: Vehicle group, 5-h preservation and vehicle (n = 8); ONO-5046 group, 5-h preservation and administration of ONO-5046 (n = 8); and Control group, minimum preservation only (n = 8). Bile output after reperfusion was significantly larger in the ONO-5046 group compared to the Vehicle group (P < 0.05 or less). Sinusoidal endothelial cell function represented by the serum hyaluronic acid concentration at 120 min after reperfusion of the ONO-5046 group was significantly lower than that in the Vehicle group (17.0 +/- 7.9 vs 36.2 +/- 14.9 ng/ml, P < 0.05), whereas serum transaminase levels 120 min after reperfusion were comparable between the two groups. Liver tissue energy charge 120 min after reperfusion was significantly better in the ONO-5046 group compared to the Vehicle group (P < 0.05). Furthermore, the number of neutrophils infiltrating the allograft after reperfusion was significantly depressed in the ONO-5046 group compared to the Vehicle group (P < 0. 02). These data suggest that the neutrophil elastase might cause liver damage early after reperfusion in cold-stored liver, which can be ameliorated by the administration of a specific neutrophil elastase inhibitor, ONO-5046.     

特异性中性粒细胞弹性蛋白酶抑制剂对大鼠移植胰腺再灌注损伤的保护作用

目的研究特异性中性粒细胞弹性蛋白酶抑制剂ＯＮＯ５０４６对移植胰腺再灌注损伤的保护作用。方法应用同系大鼠异位全胰十二指肠移植模型,ＯＮＯ５０４６治疗组的动物移植术前及术后静脉注射ＯＮＯ５０４６,术后定期分批处死受体,测定大鼠血清中性粒细胞化学趋化性细胞因子（ＣＩＮＣ）含量、移植胰腺组织中ＣＩＮＣｍＲＮＡ的表达及髓过氧化酶（ＭＰＯ）活性,并进行组织学观察。结果ＣＩＮＣ于再灌注后３小时出现峰值,治疗组为（７．２４±１．４６）μｇ／Ｌ,对照组为（２８．４±１．８５）μｇ／Ｌ,差异显著;移植物中ＣＩＮＣｍＲＮＡ于再灌注后３小时表达最强,治疗组的表达水平明显低于对照组;ＭＰＯ的活性,治疗组显著低于对照组;治疗组的胰小叶间质水肿及胰小叶间质和胰小叶内的中性粒细胞浸润较轻。结论ＯＮＯ５０４６能抑制ＣＩＮＣ的升高及ＣＩＮＣｍＲＮＡ的表达,抑制中性粒细胞的浸润,对再灌注损伤具有保护作用     

Reversible lung neutrophil accumulation can cause lung injury by elastase-mediated mechanisms

Neutrophils have been implicated in multiple models of end-organ injury. The purposes of this study were to determine whether (1) a sublethal septic insult promotes lung neutrophil accumulation, (2) this pulmonary neutrophil accumulation is reversible, (3) these accumulated neutrophils can be activated to injure lung, and (4) this pulmonary neutrophil accumulation obligates lung injury. Rats were administered low-dose endotoxin, 500 micrograms/kg, intraperitoneally, and at 6 or 12 hours, lungs were harvested and assayed for myeloperoxidase, a marker of neutrophil accumulation, and iodine 125-labeled albumin uptake, a marker of lung injury. A second set of rats were administered low-dose endotoxin and at 6 or 12 hours were given a neutrophil activator formyl-norleucyl-leucyl-phenylalanine (FNLP) 250 micrograms/kg, intravenously. At 8 or 14 hours, lungs were harvested and assayed for 125I-labeled albumin uptake. A third set of rats were administered low-dose endotoxin, and at 5 1/2 hours 30 minutes before FNLP administration, they were given a neutrophil elastase inhibitor, methyoxysuccinyl-L-alanine-L-alanine-L-proline-L-valine-chlorometh yl ketone, 2.5 mg/kg, intraperitoneally. At 6 hours rats were given FNLP, and at 8 hours lungs were harvested and assayed for 125I-labeled albumin uptake. The following results were obtained: (1) low-dose endotoxin caused a transient increase (p less than 0.05) in lung neutrophil accumulation at 6 hours, which was resolved by 12 hours; (2) lung 125I-labeled albumin uptake was unchanged both 6 and 12 hours after isolated low-dose endotoxin administration; (3) neutrophil activation increased (p less than 0.05) lung 125I-labeled albumin uptake when imposed 6 but not 12 hours after low-dose endotoxin administration; and (4) elastase inhibition decreased (p less than 0.05) the lung 125I-labeled albumin uptake promoted by endotoxin and FNLP. We conclude that sublethal endotoxemia causes a reversible lung neutrophil accumulation and that this lung neutrophil accumulation does not obligate lung injury; but activation of these accumulated neutrophils can promote lung injury, and this neutrophil-associated lung injury is mediated in part by neutrophil elastase.     

The effects of a neutrophil elastase inhibitor (ONO-5046.Na) and neutrophil depletion using a granulotrap (G-1) column on lung reperfusion injury in dogs.

BACKGROUND: Activated neutrophils are reported to be closely involved in ischemia-reperfusion injury after lung transplantation. We investigated the beneficial effects of a new recombinant specific neutrophil elastase inhibitor, ONO-5046.Na, and an extracorporeal-type granulotrap (G-1) column on ischemia-reperfusion lung injury, by using an in situ warm lung ischemia model in dogs. METHODS: Warm ischemia was induced for 3 hours by clamping the pulmonary arteries and veins. The left main bronchus was bisected and reanastomosed prior to reperfusion. The left lung was collapsed for 3 hours. A total of 27 adult mongrel dogs were divided into three groups: the control group (n = 9) treated with a saline vehicle; the ONO group (n = 9), in which ONO-5046.Na was continuously administrated from before induced ischemia and to ending 2 hours after reperfusion; and the G-1 group (n = 9), in which a G-1 column was applied for 90 minutes starting 30 minutes before reperfusion under passive bypass support. RESULTS: Circulating neutrophils in the G-1 group decreased significantly (p<.05) compared to preischemia, and significantly decreased compared with the other groups after reperfusion. Oxygenation was improved actually and pulmonary vascular resistance was kept lower level after the administration of ONO-5046.Na. The increase of lung weight was significantly ameliorated in both the G-1 and ONO groups. In the histopathological study, lungs from the control group demonstrated diffuse alveolar edema, neutrophil infiltration, massive alveolar exudate and hemorrhage, and thickening of the interstitium. Lungs from the G-1 group showed mild swelling of the alveolar wall and neutrophil infiltration. Lungs from the ONO group showed virtually no abnormalities. CONCLUSION: This study demonstrated that a neutrophil elastase inhibitor and neutrophil depletion prevented lung reperfusion injury. These treatments may prevent ischemia and reperfusion injury in lung transplantation.     

Pilot study of the effects of ONO-5046 in patients with acute respiratory distress syndrome

Evidence has linked neutrophil elastase to acute respiratory distress syndrome (ARDS), suggesting that inhibiting the activity of this enzyme could prevent the development and progression of ARDS. However, few clinical trials have examined this notion. We therefore examined the effects of ONO-5046 (sivelestat, a specific inhibitor of neutrophil elastase; sodium N-[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylaminobenzoyl]amino-acetate tetrahydrate]) in a randomized, double-blinded trial in patients with ARDS. We randomly assigned 24 patients with ARDS to groups that received conventional therapy without or with sivelestat (0.2 mg. kg(-1). h(-1)) for 14 days. The variables of interest associated with clinical outcome were the duration of mechanical ventilation; changes in oxygenation from baseline; changes in cytokine levels from baseline; number of patients alive at 30 days who did not need mechanical ventilation; and mortality rate. The length of intensive care unit stay, number of ventilation days, and mortality rates did not statistically differ between groups. ARDS was more persistent in the control than in the sivelestat group (control, 19.5 +/- 7.4 days; sivelestat, 13.5 +/- 5.9 days; P = 0.039). Neutrophil elastase activity significantly differed between groups at 72 h after treatment. Levels of interleukin-6 were lower in the sivelestat group than in the controls at 24, 48, and 72 h after treatment. ONO-5046 apparently did not affect survival or the duration of mechanical ventilation.     

Effect of a specific synthetic inhibitor of neutrophil elastase (ONO-5046) on the course of acute hemorrhagic pancreatitis in dogs

In acute pancreatitis, particularly in severe cases, polymorphonuclear neutrophil (PMN) elastase induces tissue damage in remote organs such as the lung, as well in the pancreas itself. Therefore, we examined the therapeutic effect of a specific synthetic inhibitor of PMN elastase (ONO-5046: Ono Pharmaceuticals, Osaka, Japan) on the lung, liver, and kidney, as well as pancreas, in severe hemorrhagic pancreatitis in dogs. Acute hemorrhagic pancreatitis was induced by the injection of a mixture of autologous bile and porcine trypsin into the main pancreatic duct. Lipopolysaccharide (LPS) was administered intravenously as a septic challenge. Two animal groups were used. In one group, continuous infusion of ONO-5046 was started prior to the injection of LPS (ONO group). In the other group (control), saline was infused instead. At the end of the experiment (330 min after the injection of bile and trypsin), the pancreas revealed severe hemorrhagic pancreatitis, and a large amount of bloody ascites had accumulated in the peritoneal cavity. The white blood cell count was markedly reduced in response to the induction of pancreatitis, and was decreased further by the septic attack, irrespective of the administration of ONO-5046, although the count increased again in the ONO group. Serum levels of amylase and α₂-macroglobulin-trypsin complex increased similarly in both groups following administration of bile and trypsin. Serum Ca levels decreased in both groups. At the end of the experiment, the wet weight of the lung was slightly higher in the control group (without ONO-5046). Microscopically, the pancreas showed severe hemorrhage accompanied by extensive interstitial edema in both groups. The lung and liver demonstrated mild infiltration of inflammatory cells in the interstitium in both groups, although the inflammatory change in the liver was slightly milder in the ONO group. These findings indicate that severe hemorrhagic pancreatitis cannot be alleviated by the administration of a specific inhibitor of PMN elastase alone, although this may lessen damage to remote organs such as the liver and lung. The white blood cell count decreased markedly after the induction of acute pancreatitis, and much more after a septic challenge. This seems to be closely related to the accumulation of bloody ascites in the peritoneal cavity. Received for publication on Aug. 23, 1997; accepted on April 30, 1998     

Carbon monoxide can prevent acute lung injury observed after ischemia reperfusion of the lower extremities

BACKGROUND: Pulmonary expression of heme oxygenase has been observed in multiple studies. This expression has been found beneficial in decreasing the severity of acute lung injury (ALI) post ischemia-reperfusion (I/R). The aim of this study was to assess the role of exogenous administration of the end-products of heme oxygenase reaction, carbon monoxide, and bilirubin, in the severity of ALI. STUDY DESIGN: We compared five groups of rats (n = 7/group) including a sham group and four I/R of the lower extremities by clamping the abdominal aorta for 2 h followed by reperfusion for 2 h. The four I/R groups included a control group, one pretreated with bilirubin (50 micromol/kg IV), another with inhaled carbon monoxide (CO) (250 ppm), and the last pretreated with both. The severity of ALI has been evaluated by a histological assay grading neutrophilic infiltration, as well as a study of the microvascular permeability using the Evans blue. RESULTS: The administration of CO prevented pulmonary microvascular permeability alteration noted after I/R of the lower limbs (pulmonary content of Evans blue: 141 +/- 23 microg/g of tissue in the isolated I/R group versus 68 +/- 34 microg/g of tissue in CO group; P < 0.001). Histologically CO administration inhibited neutrophilic sequestration observed after I/R. On the other hand, treatment by bilirubin alone (50 micromol/kg IV) did not modify the extent of pulmonary injury. CONCLUSION: Exogenous administration of carbon monoxide by inhalation at low doses prevented ALI post-I/R in this model.     

Attenuation of acute lung injury with propofol in endotoxemia

Endotoxin causes acute lung injury (ALI) through many mediators of inflammatory and immune responses. Propofol is an antiinflammatory and immunosuppressive drug. We conducted this study to evaluate whether propofol attenuates ALI associated with endotoxemia. Thirty-two anesthetized rabbits were randomly divided into four groups (n = 8 each). ALI was induced by IV endotoxin 5 mg/kg over 30 min in 3 groups. In 2 of the ALI groups, IV administration of propofol (2 or 5 mg/kg as a bolus followed by continuous infusion at 4 or 15 mg x kg(-1) x h(-1)) was started 15 min before endotoxin. The other ALI group received soybean-oil emulsion. The nonlung injury control group received infusion of both vehicles. The lungs were mechanically ventilated with 40% oxygen for 6 h after endotoxin. Hemodynamics did not differ among groups. The large dose of propofol attenuated lung leukosequestration, pulmonary edema (as assessed by lung wet/dry weight ratio), and pulmonary hyperpermeability (as assessed by albumin levels in bronchoalveolar lavage fluid) and resulted in better oxygenation, lung mechanics, and histological change. The small dose of propofol failed to do so. Our findings suggest that a large dose of propofol successfully mitigates physiological, biochemical, and histological deterioration in ALI in endotoxemia.     

Effects of antiplatelet agents on pulmonary haemodynamic response to fMLP in endotoxin primed rats

BACKGROUND: The interaction between neutrophils and platelets may be important in the modulation of pulmonary haemodynamics under systemic inflammatory conditions. A study was undertaken to examine whether antiplatelet agents inhibit platelet-neutrophil adherence and ameliorate the pulmonary haemodynamic response to fMLP by inhibiting thromboxane release in endotoxin primed lungs. fMLP stimulates neutrophils but not platelets; however, thromboxane synthesis in neutrophils is very low. METHODS: Rats were pretreated with either cilostazol (300 mg/kg) or aspirin (50 mg/kg) before endotoxin priming (5 mg/kg). Platelets in the lung were identified by fluorescent immunohistochemistry. Platelet-neutrophil adherence was analysed by flow cytometry of the lung vascular flush. The effect of fMLP (10(-6) M) on thromboxane release, lung weight (an indicator of pulmonary vasoconstriction), and lung filtration coefficient was determined in an isolated lung system perfused at a constant pressure difference. RESULTS: Endotoxin induced platelet accumulation and platelet-neutrophil adherence in the lung capillary were completely inhibited by cilostazol and aspirin while neutrophil recruitment was not affected. The fMLP challenge caused a significant increase in thromboxane B2 levels in endotoxin primed lungs. The fMLP induced decrease in lung weight was enhanced by endotoxin priming (from -4.9 to -63.9 mg, 95% CI of mean difference -99.5 to -10.5 mg, p<0.05). The fMLP induced increase in the lung filtration coefficient was also enhanced by endotoxin priming (from 0.63 to 2.40 mg/min/cm H2O/g, 95% CI of mean difference 1.17 to 2.37 mg/min/cm H2O/g, p<0.05). Treatment with cilostazol and aspirin completely inhibited the enhanced pulmonary haemodynamic response to fMLP. CONCLUSION: The neutrophil-platelet interaction is of critical importance in the modulation of pulmonary haemodynamics via thromboxane.     

ONO-6818, a novel, potent neutrophil elastase inhibitor, reduces inflammatory mediators during simulated extracorporeal circulation

BACKGROUND: Among the serine proteases, neutrophil elastase is a powerful cytotoxic enzyme and plays a pivotal role in the inflammatory response associated with cardiopulmonary bypass. This study assesses the effects of the specific inhibition of neutrophil elastase by a novel, potent, low-molecular-weight neutrophil elastase inhibitor, ONO-6818. We hypothesized that ONO-6818 reduces inflammatory mediators and modulates adhesion molecules and the deformability of neutrophils during simulated extracorporeal circulation. METHODS: Simulated extracorporeal circulation was established by recirculating fresh heparinized (3.75 U/mL) human blood for 120 minutes in a membrane oxygenator and a roller pump with and without 1.0 micromol/L of ONO-6818 (n = 9 for control group, n = 7 for ONO-6818 group). The neutrophil adhesion molecules, CD11b and L-selectin, and the cytoplasmic F-actin of neutrophils were measured by flow cytometry. Neutrophil deformability was evaluated using simulated silicon microcapillaries. Neutrophil elastase, interleukin 8, and C5b-9 were measured using enzyme immunoassay. RESULTS: Neutrophil elastase levels were significantly lower in the ONO-6818 group. ONO-6818 significantly reduced interleukin 8 and C5b-9 production. ONO-6818 did not modulate changes of CD11b and L-selectin during recirculation. Cytoplasmic F-actin content and changes of neutrophil deformability did not significantly differ between the groups. CONCLUSIONS: Inhibition of neutrophil elastase activity with ONO-6818 reduces further interleukin 8 production and the formation of the complement membrane attack complex, and this results in a reduction of neutrophil elastase levels during simulated extracorporeal circulation. This study suggests that specific neutrophil elastase inhibition with ONO-6818 is a feasible therapeutic option to attenuate the exaggerated inflammatory response associated with cardiopulmonary bypass.