Inhibition of neutrophil elastase activity attenuates complement-mediated lung injury in the hamster

Baicalin relieves complement alternative pathway activation-induced lung inflammation through inhibition of NF-κB pathway

INTRODUCTION

Acute lung injury (ALI) as one kind of acute pulmonary inflammatory disorder, manifests primarily as damage to alveolar epithelial cells and microvascular endothelial cells. Activation of the complement system is a common pathological mechanism in ALI induced by diverse factors, with the complement alternative pathway assuming a pivotal role. Baicalin, a flavonoid derived from the root of Scutellaria baicalensis Georgi, exhibits noteworthy biological activities. The present study attempted the interventional effects and underlying mechanisms of baicalin in microangiopathy in ALI induced by complement alternative pathway activation.

METHODS

Activation of the complement alternative pathway by cobra venom factor (CVF). HMEC cells were pretreated with baicalin and then exposed to complement activation products. The expression of inflammatory mediators was detected by ELISA, and the intranuclear transcriptional activity of NF-κB was assessed by a dual fluorescent kinase reporter gene assay kit. Before establishing the ALI mouse model, baicalin or PDTC was gavaged for 7 d. CVF was injected into the tail vein to establish the ALI model. The levels of inflammatory mediators in BALF and serum were determined by ELISA. HE staining and immunohistochemistry evaluated pathological changes, complement activation product deposition, and NF-κB p65 phosphorylation in lung tissue.

RESULTS

Baicalin reduced complement alternative activation product-induced expression of HMEC cells adhesion molecules (ICAM-1, VCAM-1, E-selectin) and cytokines (IL-6, TNF-α) as well as upregulation of NF-κB intranuclear transcriptional activity. Baicalin intervention reduced the number of inflammatory cells and protein content in the BALF and decreased the levels of IL-6, TNF-α, and ICAM-1 in serum and IL-6, TNF-α, ICAM-1, and P-selectin in BLAF. In addition, baicalin attenuated inflammatory cell infiltration in the lung of ALI mice and reduced the deposition of complement activation products (C5a, C5b-9) and phosphorylation of NF-κB p65 in lung tissue.

CONCLUSION

Baicalin relieves complement alternative pathway activation-induced lung inflammation by inhibition of NF-κB pathway, delaying the progression of ALI.

Secretory leukocyte protease inhibitor protects against severe urinary tract infection in mice

Millions suffer from urinary tract infections (UTIs) worldwide every year with women accounting for the majority of cases. Uropathogenic Escherichia coli (UPEC) causes most of these primary infections and leads to 25% becoming recurrent or chronic. To repel invading pathogens, the urinary tract mounts a vigorous innate immune response that includes the secretion of antimicrobial peptides (AMPs), rapid recruitment of phagocytes, and exfoliation of superficial umbrella cells. Here, we investigate secretory leukocyte protease inhibitor (SLPI), an AMP with antiprotease, antimicrobial, and immunomodulatory functions, known to play protective roles at other mucosal sites, but not well characterized in UTIs. Using a preclinical model of UPEC-caused UTI, we show that urine SLPI increases in infected mice and that SLPI is localized to bladder epithelial cells. UPEC-infected SLPI-deficient (Slpi-/-) mice suffer from higher urine bacterial burdens, prolonged bladder inflammation, and elevated urine neutrophil elastase (NE) levels compared to wild-type (Slpi+/+) controls. Combined with bulk bladder RNA sequencing, our data indicate that Slpi-/- mice have a dysregulated immune and tissue repair response following UTI. We also measure SLPI in urine samples from a small group of female subjects 18-49 years old and find that SLPI tends to be higher in the presence of a uropathogen, except in patients with a history of recent or recurrent UTI, suggesting a dysregulation of SLPI expression in these women. Taken together, our findings show SLPI promotes clearance of UPEC in mice and provides preliminary evidence that SLPI is likewise regulated in response to uropathogen exposure in women.IMPORTANCEAnnually, millions of people suffer from urinary tract infections (UTIs) and more than $3 billion are spent on work absences and treatment of these patients. While the early response to UTI is known to be important in combating urinary pathogens, knowledge of host factors that help curb infection is still limited. Here, we use a preclinical model of UTI to study secretory leukocyte protease inhibitor (SLPI), an antimicrobial protein, to determine how it protects the bladder against infection. We find that SLPI is increased during UTI, accelerates the clearance of bacteriuria, and upregulates genes and pathways needed to fight an infection while preventing prolonged bladder inflammation. In a small clinical study, we show SLPI is readily detectable in human urine and is associated with the presence of a uropathogen in patients without a previous history of UTI, suggesting SLPI may play an important role in protecting from bacterial cystitis.

Secretory Leukocyte Protease Inhibitor Protects Against Severe Urinary Tract Infection in Mice

Millions suffer from urinary tract infections (UTIs) worldwide every year with women accounting for the majority of cases. Uropathogenic Escherichia coli (UPEC) causes most of these primary infections and leads to 25% becoming recurrent or chronic. To repel invading pathogens, the urinary tract mounts a vigorous innate immune response that includes the secretion of antimicrobial peptides (AMPs), rapid recruitment of phagocytes and exfoliation of superficial umbrella cells. Here, we investigate secretory leukocyte protease inhibitor (SLPI), an AMP with antiprotease, antimicrobial and immunomodulatory functions, known to play protective roles at other mucosal sites, but not well characterized in UTIs. Using a mouse model of UPEC-caused UTI, we show that urine SLPI increases in infected mice and that SLPI is localized to bladder epithelial cells. UPEC infected SLPI-deficient (Slpi-/-) mice suffer from higher urine bacterial burdens, prolonged bladder inflammation, and elevated urine neutrophil elastase (NE) levels compared to wild-type (Slpi+/+) controls. Combined with bulk bladder RNA sequencing, our data indicate that Slpi-/- mice have a dysregulated immune and tissue repair response following UTI. We also measure SLPI in urine samples from a small group of female subjects 18-49 years old and find that SLPI tends to be higher in the presence of a uropathogen, except in patients with history of recent or recurrent UTI (rUTI), suggesting a dysregulation of SLPI expression in these women. Taken together, our findings show SLPI protects against acute UTI in mice and provides preliminary evidence that SLPI is likewise regulated in response to uropathogen exposure in women.

Effects of intravenous sivelestat sodium on prevention of acute respiratory distress syndrome in patients with sepsis: study protocol for a double-blind multicentre randomised controlled trial

INTRODUCTION

Sepsis is one of the most common risk factors for acute respiratory distress syndrome (ARDS). Neutrophil elastase (NE) is believed to be an important mediator of ARDS. When sepsis occurs, a large number of inflammatory factors are activated and released, which makes neutrophils migrate into the lung, eventually leading to the occurrence of ARDS. Sivelestat sodium is an NE inhibitor that can inhibit the inflammatory reaction during systemic inflammatory response syndrome and alleviate lung injury. Therefore, we hypothesise that intravenous sivelestat sodium may prevent the occurrence of ARDS in patients with sepsis.

METHODS AND ANALYSIS

This is a prospective, investigator-initiated, double-blind, adaptive, multicentre, randomised, controlled clinical trial with an adaptive 'sample size re-estimation' design. Patients meeting the inclusion criteria who were transferred into the intensive care unit will be randomly assigned to receive sivelestat sodium or placebo for up to 7 days. The primary outcome is the development of ARDS within 7 days after randomisation. A total of 238 patients will be recruited based on a 15% decrease in the incidence of ARDS in the intervention group in this study. A predefined interim analysis will be performed to ensure that the calculation is reasonable after reaching 50% (120) of the planned sample size.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of ZhongDa Hospital affiliated to Southeast University (identifier: Clinical Ethical Approval No. 2021ZDSYLL153-P03). Results will be submitted for publication in peer-reviewed journals and presented at relevant conferences and meetings.

TRIAL REGISTRATION NUMBER

NCT04973670.

Complement as a vital nexus of the pathobiological connectome for acute respiratory distress syndrome: An emerging therapeutic target

The hallmark of acute respiratory distress syndrome (ARDS) pathobiology is unchecked inflammation-driven diffuse alveolar damage and alveolar-capillary barrier dysfunction. Currently, therapeutic interventions for ARDS remain largely limited to pulmonary-supportive strategies, and there is an unmet demand for pharmacologic therapies targeting the underlying pathology of ARDS in patients suffering from the illness. The complement cascade (ComC) plays an integral role in the regulation of both innate and adaptive immune responses. ComC activation can prime an overzealous cytokine storm and tissue/organ damage. The ARDS and acute lung injury (ALI) have an established relationship with early maladaptive ComC activation. In this review, we have collected evidence from the current studies linking ALI/ARDS with ComC dysregulation, focusing on elucidating the new emerging roles of the extracellular (canonical) and intracellular (non-canonical or complosome), ComC (complementome) in ALI/ARDS pathobiology, and highlighting complementome as a vital nexus of the pathobiological connectome for ALI/ARDS via its crosstalking with other systems of the immunome, DAMPome, PAMPome, coagulome, metabolome, and microbiome. We have also discussed the diagnostic/therapeutic potential and future direction of ALI/ARDS care with the ultimate goal of better defining mechanistic subtypes (endotypes and theratypes) through new methodologies in order to facilitate a more precise and effective complement-targeted therapy for treating these comorbidities. This information leads to support for a therapeutic anti-inflammatory strategy by targeting the ComC, where the arsenal of clinical-stage complement-specific drugs is available, especially for patients with ALI/ARDS due to COVID-19.

Acteoside attenuates acute lung injury following administration of cobra venom factor to mice

Background

Acteoside, a water-soluble active constituent of diverse valuable medicinal vegetation, has shown strong anti-inflammatory property. However, studies on the anti-inflammatory property of acteoside in complement-induced acute lung injury (ALI) are limited. Therefore, this study aims to evaluate the anti-inflammatory activity of acteoside in cobra venom factor (CVF)-stimulated human microvascular endothelial cells (HMEC) and in ALI mice model.

Methods

In this study, we investigated the effects of acteoside (20, 10, and 5 μg/mL) in vitro in CVF induced HMECs and the activity of acteoside (100, 50, and 20 mg/kg/day bodyweight) in vivo in CVF induced ALI mice. Each eight male mice were orally administered acteoside or the positive drug PDTC (100 mg/kg/day) for 7 days before CVF (35 μg/kg) injection. After injection for 1 h, the pharmacological effects of acteoside were investigated by spectrophotometry, pathological examination, enzyme-linked immunosorbent assay, and immunohistochemistry.

Results

In vitro, acteoside (20, 10, and 5 μg/mL) reduced the protein expression of adhesion molecules and pro-inflammatory cytokines and transcriptional activity of NF-κB (P < 0.01). In vivo studies showed that acteoside dose-dependently alleviated lung histopathologic lesion, inhibited the production of the protein content of BALF, leukocyte cell number, lung MPO activity, and expression levels of IL-6, TNF-α, and ICAM-1, and suppressed the C5b-9 deposition and NF-κB activation in CVF-induced acute lung inflammation in mice (P < 0.05, 0.01).

Conclusion

This study demonstrates that acteoside exerts strong anti-inflammatory activities in the CVF-induced acute lung inflammation model and suggests that acteoside is a potential therapeutic agent for complement-related inflammatory diseases.

Genetic and Pharmacologic Inhibition of the Neutrophil Elastase Inhibits Experimental Atherosclerosis

Background

To investigate whether neutrophil elastase (NE) plays a causal role in atherosclerosis, and the molecular mechanisms involved.

Methods and Results

NE genetic–deficient mice (Apolipoprotein E^−/−/NE^−/− mice), bone marrow transplantation, and a specific NE inhibitor (GW311616A) were employed in this study to establish the causal role of NE in atherosclerosis. Aortic expression of NE mRNA and plasma NE activity was significantly increased in high‐fat diet (HFD)–fed wild‐type (WT) (Apolipoprotein E^−/−) mice but, as expected, not in NE‐deficient mice. Selective NE knockout markedly reduced HFD‐induced atherosclerosis and significantly increased indicators of atherosclerotic plaque stability. While plasma lipid profiles were not affected by NE deficiency, decreased levels of circulating proinflammatory cytokines and inflammatory monocytes (Ly6C^hi/CD11b⁺) were observed in NE‐deficient mice fed with an HFD for 12 weeks as compared with WT. Bone marrow reconstitution of WT mice with NE^−/− bone marrow cells significantly reduced HFD‐induced atherosclerosis, while bone marrow reconstitution of NE^−/− mice with WT bone marrow cells restored the pathological features of atherosclerotic plaques induced by HFD in NE‐deficient mice. In line with these findings, pharmacological inhibition of NE in WT mice through oral administration of NE inhibitor GW311616A also significantly reduced atherosclerosis. Mechanistically, we demonstrated that NE promotes foam cell formation by increasing ATP‐binding cassette transporter ABCA1 protein degradation and inhibiting macrophage cholesterol efflux.

Conclusions

We outlined a pathogenic role for NE in foam cell formation and atherosclerosis development. Consequently, inhibition of NE may represent a potential therapeutic approach to treating cardiovascular disease.

Effects of the early administration of sivelestat sodium on bronchopulmonary dysplasia in infants: A retrospective cohort study

BACKGROUND

Chorioamnionitis, or infiltration of the chorioamnion by neutrophils, is a risk factor associated with the development of bronchopulmonary dysplasia. Increased neutrophil elastase levels are observed in the tracheal aspirates of these patients.

AIMS

To examine the effects of early administration of the selective neutrophil elastase inhibitor sivelestat, which is used to treat acute lung injury in adults, on bronchopulmonary dysplasia in extremely premature infants.

STUDY DESIGN

Retrospective cohort study.

SUBJECTS

This study included extremely low-birth-weight infants born at a gestational age<28weeks. Patients were divided into groups based on the receipt of sivelestat.

OUTCOME MEASURES

The primary outcome was the rate of bronchopulmonary dysplasia-free survival at a postmenstrual age of 36weeks, and the secondary outcomes included various clinically significant factors of neonatal mortality and morbidity and adverse events.

RESULTS

Of the 1031 included neonates, 124 (12.0%) were treated with sivelestat. Significant differences between the groups were noted for gestational age, delivery method, fetal number, the frequency of chorioamnionitis, immunoglobulin M levels, and WBC counts. No differences were identified concerning the bronchopulmonary dysplasia-free survival rate at a postmenstrual age of 36weeks (adjusted odds ratio for sivelestat to control, 0.83; 95% confidence interval=0.53-1.30). Secondary outcomes did not significantly differ between the groups.

CONCLUSIONS

In extremely premature infants, early sivelestat use was not associated with an improved rate of survival without bronchopulmonary dysplasia at a postmenstrual age of 36weeks.

Cyclosporine Does Not Prevent Microvascular Loss in Transplantation but Can Synergize With a Neutrophil Elastase Inhibitor, Elafin, to Maintain Graft Perfusion During Acute Rejection

The loss of a functional microvascular bed in rejecting solid organ transplants is correlated with fibrotic remodeling and chronic rejection; in lung allografts, this pathology is predicted by bronchoalveolar fluid neutrophilia which suggests a role for polymorphonuclear cells in microcirculatory injury. In a mouse orthotopic tracheal transplant model, cyclosporine, which primarily inhibits T cells, failed as a monotherapy for preventing microvessel rejection and graft ischemia. To target neutrophil action that may be contributing to vascular injury, we examined the effect of a neutrophil elastase inhibitor, elafin, on the microvascular health of transplant tissue. We showed that elafin monotherapy prolonged microvascular perfusion and enhanced tissue oxygenation while diminishing the infiltration of neutrophils and macrophages and decreasing tissue deposition of complement C3 and the membrane attack complex, C5b-9. Elafin was also found to promote angiogenesis through activation of the extracellular signal-regulated kinase (ERK) signaling pathway but was insufficient as a single agent to completely prevent tissue ischemia during acute rejection episodes. However, when combined with cyclosporine, elafin effectively preserved airway microvascular perfusion and oxygenation. The therapeutic strategy of targeting neutrophil elastase activity alongside standard immunosuppression during acute rejection episodes may be an effective approach for preventing the development of irreversible fibrotic remodeling.

Clinical utility of the neutrophil elastase inhibitor sivelestat for the treatment of acute respiratory distress syndrome

Acute respiratory distress syndrome is a serious condition that can arise following direct or indirect lung injury. It is heterogeneous and has a high mortality rate. Supportive care is the mainstay of treatment and there is no definitive pharmacological treatment as yet. Sivelestat is a neutrophil elastase inhibitor approved in Japan and the Republic of Korea for acute lung injury, including acute respiratory distress syndrome in patients with systemic inflammatory response syndrome. The aim of this review is to examine the clinical utility of sivelestat in different disease states, using data from nonclinical and clinical studies. In nonclinical studies, sivelestat appears to show benefit in acute lung injury without inhibiting the host immune defense in cases of infection. Clinical studies do not yet provide a clear consensus. Phase III and IV Japanese studies have shown improvements in pulmonary function, length of intensive care unit stay, and mechanical ventilation, but a non-Japanese multicenter study did not demonstrate sivelestat to have an effect on ventilator-free days or 28-day all-cause mortality. Evidence of improvement in various parameters, including duration of stay in intensive care, mechanical ventilation, the ratio of partial pressure of arterial oxygen and fraction of inspired oxygen (PaO₂/F_IO₂ ratio) ratio, and lung injury scores, has been shown in patients with sepsis or gastric aspiration, and following the surgical treatment of esophageal cancer. To date, there are no particular concerns regarding adverse events, and the available data do not suggest that sivelestat might worsen infections. One study has analyzed cost-effectiveness, finding that sivelestat may reduce costs compared with standard care. The currently available evidence suggests that sivelestat may show some benefit in the treatment of acute lung injury/acute respiratory distress syndrome, although large, randomized controlled trials are needed in specific pathophysiological conditions to explore these potential benefits.

Effects of sivelestat treatment on acute lung injury in paraquat-intoxicated rats

Lung injury is the main cause of death in acute paraquat (PQ) intoxication. Sivelestat (SV), a neutrophil elastase inhibitor, is effective in reducing inflammation in acute lung injury. The aim of this study was to examine the effect of SV on acute lung injury in PQ-intoxicated rats. Seven-week-old male Sprague-Dawley rats were randomly assigned to four groups: (1) control group (group N; n = 5); (2) PQ + normal saline (group P; n = 6); (3) normal saline + SV (group S; n = 6) and (4) PQ + SV (group PS; n = 6). SV treatment (intraperitoneally [i.p.], 20 mg/kg) was performed 30 minutes after PQ injection (i.p., 100 mg/kg), and injections were continued every hour for a total of five doses. One hour after the last treatment, blood samples were obtained for analysis of interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α). Lung sections were stained with hematoxylin--eosin for light microscopic analysis. Neutrophil infiltration score of group PS was significantly lower than that of group P (p < 0.05). But, other scores and total score had no significant differences. IL-6 of group PS did not differ, compared to group P. In addition, there were no differences among the four groups. TNF-α of group PS was reduced, in comparison to the level of group P. SV attenuated neutrophil infiltration in PQ-induced acute lung injury in rats. In addition, systemic inflammation was partially suppressed with SV treatment, suppressing TNF-α production. These results suggest that SV reduces paraquat-induced lung injury, at least partially, by inhibiting neutrophil infiltration and TNF-α secretion.

The use of neutrophil elastase inhibitor in the treatment of acute lung injury after pneumonectomy

Background

The prognosis of acute lung injury (ALI) after pneumonectomy is poor, with reported mortality rates of 30-100%. Neutrophil elastase inhibitor (NEI) is known to prevent lung injury caused by neutrophil elastase and improve lung function in ALI. We evaluated the effect of NEI on ALI after pneumonectomy.

Methods

We analyzed nine patients who required ventilator care due to ALI after pneumonectomy. Five of these patients underwent conventional ventilator care (group I), and four patients underwent ventilator care and were administrated NEI (group II). We retrospectively analyzed the lung injury score (LIS) for 10 days after intubation.

Results

The LIS before intubation satisfied the diagnostic criteria of ALI or acute respiratory distress syndrome (ARDS) in all patients. After intubation, the LIS improved in both groups. But, as times went on, the mean value of the LIS in group II was lower compared to group I. In group I, only one patient underwent extubation. In group II, extubation was possible in three patients. Mortality rates were 80% in group I and 25% in group II.

Conclusions

We conclude that NEI may improve the lung function, shorten the duration of mechanical ventilation, and reduce mortality in patients with ALI after pneumonectomy.

Preventive effect of sivelestat on postoperative respiratory disorders after thoracic esophagectomy

PURPOSE

Sivelestat, a selective inhibitor of neutrophil elastase, has been reported to reduce acute lung injury associated with systemic inflammatory response syndrome. This study retrospectively investigated the effect of sivelestat on respiratory function in patients who underwent esophagectomy.

METHODS

Patients who underwent esophagectomy for thoracic esophageal cancer between 2005 and 2010 were included in this study. Forty-two were treated perioperatively with sivelestat (4.8 mg/kg/day; sivelestat group) and the remaining 35 were not (control group). Sivelestat was administered continuously from the beginning of surgery until postoperative day 3. All patients were administered methylprednisolone for 3 days. The perioperative clinical and laboratory data, total sequential organ failure assessment score, PaO2/FiO2 ratio (P/F ratio) and postoperative complications were compared between the two groups.

RESULTS

There were no significant differences between the groups in the patients' background data. The P/F ratio immediately after surgery was significantly higher in the sivelestat group than in the control group (p < 0.05). The respiratory rate immediately after surgery and the temperature on postoperative day 2 were significantly lower in the sivelestat group than in the control group (p < 0.05). There were no differences in any of the other clinical data or complications.

CONCLUSIONS

Perioperative administration of sivelestat improves postoperative respiratory function in patients after esophagectomy.

Sivelestat sodium hydrate reduces radiation-induced lung injury in mice by inhibiting neutrophil elastase

The aim of this study was to investigate whether sivelestat, a neutrophil elastase (NE) inhibitor, mitigates radiation-induced lung injury in mice. C57BL/6J mice were administered a dose of 20 Gy to the bilateral whole lungs. Sivelestat was administered immediately before and 1 h after irradiation in group RE2, and immediately before and 1, 3 and 6 h after irradiation in group RE4. Group R received irradiation without sivelestat injection. Mice that did not receive sivelestat injection or irradiation were used as controls. NE activity was measured 24 and 48 h after irradiation, and the mice were sacrificed 24 h, 48 h and 15 weeks after irradiation for histopathological examination. In groups RE2 and RE4, NE activity was significantly suppressed until 48 h after irradiation compared to group R. The degree of lung damage in each group was scored during histopathological examination. Results showed that the scores of groups RE2 and RE4 were significantly lower compared to those of group R 15 weeks after irradiation. In conclusion, sivelestat reduced radiation‑induced lung injury in the mice by suppressing NE activity and excessive inflammatory reactions.

WFDC1/ps20: a host factor that influences the neutrophil response to murine hepatitis virus (MHV) 1 infection

The whey acidic protein family member, WFDC1/ps20 is a permissivity factor in HIV infection. Herein we describe a contrasting role for ps20 in limiting MHV-1 infection. Intranasal MHV-1 infection produces a respiratory infection in mice. Using ps20 knockout mice we provide evidence that intranasal MHV-1 infection results in increased lung viral titers in ps20^−/− compared to ps20^+/+ mice. Accompanying MHV-1 infection we observe an increase in the number of neutrophils infiltrating the BAL and an increase in the percentage of neutrophils in the lung draining lymph nodes of ps20^−/− compared with ps20^+/+ mice. Gene expression levels for the neutrophil chemoattractants CXCL1 and CXCL2 are elevated in the lungs of ps20^−/− mice post-MHV-1 infection. Characterization of the immune cell profile in naïve ps20^−/− mice revealed an increase in circulating neutrophils compared to ps20^+/+ mice. No notable differences in other immune cell profiles were observed between the ps20^+/+ and ps20^−/− mice. Accordingly, we examined MHV-1 infection of neutrophils and provide evidence that neutrophils isolated from ps20^−/− mice are more susceptible to MHV-1 infection than neutrophils isolated from ps20^+/+ mice. These data suggest roles for ps20 in regulating expression of neutrophil-specific chemotactic factors, thereby potentially modulating neutrophil migration, and in modulating neutrophil susceptibility to MHV-1 infection.

Combined effects of a neutrophil elastase inhibitor (sivelestat sodium) and a free radical scavenger (edaravone) on lipopolysaccharide-induced acute lung injury in rats

OBJECTIVE AND DESIGN

The present study aimed to investigate the combined effects of a neutrophil elastase inhibitor, sivelestat sodium, with a free radical scavenger, edaravone, on lipolysaccharide (LPS)-induced acute lung injury (ALI).

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were anesthetized and instilled intratracheally with 2 mg/kg LPS. Sivelestat sodium (10 mg/kg, i.p.) and/or edaravone (8 mg/kg, i.p.) were administered 1 h after LPS instillation. The severity of pulmonary injuries was evaluated 12 h after inducing acute lung injury.

RESULTS

In lung tissues, either sivelestat or edaravone treatment alone showed significant protective effects against neutrophil infiltration and tissue injury, as demonstrated by myeloperoxidase activity and histopathological analysis. Sivelestat or edaravone treatment also attenuated the LPS-induced production of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) in rat lungs. However, the LPS-induced elevation of malondialdehyde levels in rat lungs was reduced only by edaravone, but not by sivelestat. In addition, combined treatment with both sivelestat and edaravone demonstrated additive protective effects on LPS-induced lung injury, compared with single treatments.

CONCLUSIONS

Combination of sivelestat and edaravone shows promise as a new treatment option for ALI/acute respiratory distress syndrome patients.

Early administration of sivelestat, the neutrophil elastase inhibitor, in adults for acute lung injury following gastric aspiration

Gastric aspiration is the major cause of acute lung injury (ALI) and acute respiratory distress syndrome. Aspiration-induced ALI is believed to be, at least in part, facilitated by neutrophil-derived mediators and toxic molecules. We conducted a prospective cohort study based on the hypothesis that sivelestat, a specific neutrophil elastase inhibitor, is effective for treating ALI following gastric aspiration. Forty-four ALI patients who showed evidence of aspiration were observed within 12 h before intensive care unit admission and who had been mechanically ventilated within 12 h after admission were included in this study. Lung injury score (LIS) and PAO2/FiO2 (P/F) ratio on day 7 were defined as the primary outcomes of the study. Twenty-three patients were assigned to the sivelestat group and 21 to the control group. In univariate analyses, the proportions of patients with LIS lower than 1.0 on day 7 and a P/F greater than 300 on day 7 were significantly higher in the sivelestat group than in the control group (60.9% vs. 26.3%, P = 0.03; 87.0% vs. 36.8%, P = 0.001). In the logistic regression model, the use of sivelestat was an independent predictor for LIS lower than 1.0 on day 7 (relative risk, 7.4; 95% confidence interval [CI], 1.51-36.48) and for a P/F ratio higher than 300 on day 7 (relative risk, 18.5; 95% CI, 2.72-126.46). In the Cox proportional hazards model, the use of sivelestat was associated with a lower cumulative proportion of patients who received mechanical ventilation during the initial 14 days (hazard ratio, 2.6; 95% CI, 1.17-5.55).

The effect of sivelestat sodium hydrate on severe respiratory failure after thoracic aortic surgery with deep hypothermia

Patients who undergo thoracic aortic surgery with deep hypothermia frequently have postoperative respiratory failure as a complication. Severe lung injury in these patients results in a fatal outcome. A specific neutrophil elastase inhibitor, sivelestat sodium hydrate, is an innovative therapeutic drug for acute lung injury. We evaluated the protective effects of sivelestat sodium hydrate on severe lung injury after thoracic aortic surgery with deep hypothermia. From January 2002 to July 2007, 71 consecutive patients underwent thoracic aortic surgery with deep hypothermia. Of these patients, 22 had postoperative respiratory failure with PaO₂/FiO₂ ratios of less than 150. They were randomly assigned to one of two groups. The first group (Group S, n = 10) was administered sivelestat sodium hydrate continuously at 0.2 mg/kg/h until weaning from mechanical ventilation; the second group (Group C, n = 12) was not administered sivelestat sodium hydrate. The groups were comparable with respect to clinical data. There were no significant differences between the two groups in age, operation duration, total cardiopulmonary bypass time, circulatory ischemia time, cardiac arrest time, intraoperative blood loss, and total transfusion volume. The improvement of pulmonary function was observed in the both groups, but more marked in Group S by statistical analysis using analysis of variance for repeated measurements. Especially, in the early phase, pulmonary function improvement was more marked in Group S. The duration of mechanical ventilation, the length of stay in the intensive care unit, and the length of hospital stay were shorter in Group S, but not significantly. Sivelestat sodium hydrate is a specific neutrophil elastase inhibitor that improves pulmonary function in patients with severe postoperative respiratory failure following thoracic aortic surgery with deep hypothermia. The drug may shorten the duration of postoperative ventilation, intensive care unit stay, and hospital stay.

The protective function of neutrophil elastase inhibitor in liver ischemia/reperfusion injury

BACKGROUND.: A neutrophil elastase (NE) inhibitor, Sivelestat, has been approved for the treatment of acute lung injury associated with systemic inflammation in humans. Some reports have also shown its protective effects in liver inflammatory states. We have recently documented the importance of NE in the pathophysiology of liver ischemia/reperfusion injury, a local Ag-independent inflammation response. This study was designed to explore putative cytoprotective functions of clinically available Sivelestat in liver ischemia/reperfusion injury. METHODS.: Partial warm ischemia was produced in the left and middle hepatic lobes of C57BL/6 mice for 90 min, followed by 6 or 24 hr of reperfusion. The mice were given Sivelestat (100 mg/kg, subcutaneous) at 10 min before ischemia, 10 min before reperfusion, and at 1 and 3 hr of reperfusion thereafter. RESULTS.: Sivelestat treatment significantly reduced serum alanine aminotransferase levels and NE activity, when compared with controls. Histological liver examination has revealed that unlike in controls, Sivelestat ameliorated the hepatocellular damage and decreased local neutrophil activity and infiltration. The expression of proinflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), chemokines (CXCL-1, CXCL-2, and CXCL-10), and toll-like receptor 4 was significantly reduced in the treatment group, along with diminished apoptosis through caspase-3 pathway. Moreover, in vitro studies confirmed downregulation of proinflammatory cytokine and chemokine programs in mouse macrophage cell cultures, along with depression of innate toll-like receptor 4 signaling. CONCLUSION.: Sivelestat-mediated NE inhibition may represent an effective therapeutic option in liver transplantation and other inflammation disease states.

The inhibition of neutrophil elastase ameliorates mouse liver damage due to ischemia and reperfusion

Neutrophils are considered crucial effector cells in the pathophysiology of organ ischemia/reperfusion injury (IRI). Although neutrophil elastase (NE) accounts for a substantial portion of the neutrophil activity, the function of NE in liver IRI remains unclear. This study focuses on the role of NE in the mechanism of liver IRI. Partial warm ischemia was produced in the left and middle hepatic lobes of C57BL/6 mice for 90 minutes, and this was followed by 6 to 24 hours of reperfusion. Mice were treated with neutrophil elastase inhibitor (NEI; 2 mg/kg per os) at 60 minutes prior to the ischemia insult. NEI treatment significantly reduced serum alanine aminotransferase levels in comparison with controls. Histological examination of liver sections revealed that unlike in controls, NEI treatment ameliorated hepatocellular damage and decreased local neutrophil infiltration, as assessed by myeloperoxidase assay, naphthol AS-D chloroacetate esterase stains, and immunohistochemistry (anti-Ly-6G). The expression of pro-inflammatory cytokines (tumor necrosis factor alpha and interleukin 6) and chemokines [chemokine (C-X-C motif) ligand 1 (CXCL-1), CXCL-2, and CXCL-10] was significantly reduced in the NEI treatment group, along with diminished apoptosis, according to terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining and caspase-3 activity. In addition, toll-like receptor 4 (TLR4) expression was diminished in NEI-pretreated livers, and this implies a putative role of NE in the TLR4 signal transduction pathway. Thus, targeting NE represents a useful approach for preventing liver IRI and hence expanding the organ donor pool and improving the overall success of liver transplantation. Liver Transpl 15:939-947, 2009. (c) 2009 AASLD.

Leukocyte elastase induces lung epithelial apoptosis via a PAR-1-, NF-kappaB-, and p53-dependent pathway

Leukocyte elastase induces apoptosis of lung epithelial cells via alterations in mitochondrial permeability, but the signaling pathways regulating this response remain uncertain. Here we investigated the involvement of proteinase-activated receptor-1 (PAR-1), the transcription factor NF-kappaB, and the protooncogene p53 in this pathway. Elastase-induced apoptosis of lung epithelial cells correlated temporally with activation of NF-kappaB, phosphorylation, and nuclear translocation of p53, increased p53 up-regulated modulator of apoptosis (PUMA) expression, and mitochondrial translocation of Bax resulting in enhanced permeability. Elastase-induced apoptosis was also prevented by pharmacologic inhibitors of NF-kappaB and p53 and by short interfering RNA knockdown of PAR-1, p53, or PUMA. These inhibitors prevented elastase-induced PUMA expression, mitochondrial translocation of Bax, increased mitochondrial permeability, and attenuated apoptosis. NF-kappaB inhibitors also reduced p53 phosphorylation. We conclude that elastase-induced apoptosis of lung epithelial cells is mediated by a PAR-1-triggered pathway involving activation of NF-kappaB and p53, and a PUMA- and Bax-dependent increase in mitochondrial permeability leading to activation of distal caspases. Further, p53 contributes to elastase-induced apoptosis by both transcriptional and post-transcriptional mechanisms.

A neutrophil elastase inhibitor, sivelestat, improved respiratory and cardiac function in pediatric cardiovascular surgery with cardiopulmonary bypass

PURPOSE

Several reports indicate that a neutrophil elastase inhibitor, sivelestat, may have prophylactic efficacy against a systemic inflammatory response after cardiovascular surgery with cardiopulmonary bypass (CPB). We evaluated the clinical pulmonary and cardiac effects of sivelestat.

METHODS

We performed a retrospective study of 25 pediatric patients who underwent elective cardiovascular surgery with CPB for ventricular septal defect with pulmonary hypertension. Ten patients received 0.2 mg x kg(-1) x h(-1) sivelestat; the other is patients were the control group. There were no significant differences in demographic characteristics between the two groups. The P(a)O(2)/fractional inspired oxygen (F(I)O(2); P/F) ratio, the respiratory index (RI), and the fractional area change (FAC) of the left ventricle (LV) in the postoperative course were measured.

RESULTS

The P/F ratio was higher in the sivelestat group compared with the control group and there were significant differences between the two groups immediately after weaning form CPB, and at 12 h after weaning from CPB (P < 0.05). The RI was lower in the sivelestat group compared with the control group and there were significant differences between the two groups at immediately after weaning from CPB, and at 6 h and 12 h after CPB (P < 0.05). The FAC of the LV was significantly better in the sivelestat group and there was a significant difference between the two groups on postoperative day (POD) 3 (P < 0.05).

CONCLUSION

We have shown that pediatric patients who underwent cardiovascular surgery with CPB who received sivelestat had a higher P/F ratio, a lower RI, and better FAC of the LV in the postoperative course.

The involvement of nitric oxide, nitric oxide synthase, neutrophil elastase, myeloperoxidase and proinflammatory cytokines in the acute lung injury caused by phorbol myristate acetate

Phorbol myristate acetate (PMA) causes acute lung injury (ALI). The present study was designed to elucidate the role of nitric oxide (NO), inducible NO synthase (iNOS), neutrophil elastase (NE) and other mediators in the ALI caused by PMA. In isolated rat's lungs, PMA at various doses (1, 2 and 4 mug/g lung weight) was added into the lung perfusate. Vehicle group received dimethyl sulfoxide (the solvent for PMA) 100 mug/g. We measured the lung weight changes, pulmonary arterial pressure, capillary filtration coefficient, exhaled NO, protein concentration in bronchoalveolar lavage (PCBAL) and Evan blue dye leakage. Nitrate/nitrite, methyl guanidine, proinflammatory cytokines, NE and myeloperoxidase (MPO) in lung perfusate were determined. Histopathological examination was performed. We detected the iNOS mRNA expression in lung tissue. PMA caused dose-dependent increases in variables for lung changes, and nitrate/nitrite, methyl guanidine, proinflammatory cytokines, NE and MPO in lung perfusate. The pathology was characterized by alveolar hemorrhagic edema with inflammatory cell infiltration. Scanning electron microscopy revealed endothelial damage. PMA upregulated the expression of iNOS mRNA. Our results suggest that neutrophil activation by PMA causes release of NE, upregulation of iNOS and a series of inflammatory responses leading to endothelial damage and ALI.

Addition of a neutrophil elastase inhibitor to the organ flushing solution decreases lung reperfusion injury in rat lung transplantation

BACKGROUND

Neutrophil elastase plays an important role in ischemia-reperfusion injury. We hypothesized that the addition of sivelestat, a specific neutrophil elastase inhibitor, to the organ flushing solution would decrease reperfusion injury in a rat single left-lung transplant model.

METHODS

All donor lungs were flushed with 25 ml low-potassium dextran-glucose solution and stored for 16 h at 4 degrees C. Rats were divided into three experimental groups (n=10) that received donor lungs washed in either normal flushing solution (group 1), or flushing solution containing 20mg sivelestat (group 2) or 40 mg sivelestat (group 3). Graft function was assessed 48 h after reperfusion using five measurements: isolated graft oxygenation, wet/dry ratio, peak airway pressure, tissue myeloperoxidase activity, and serum lipid peroxides level. Histological examination of lung grafts was also performed.

RESULTS

Group 3 showed better oxygenation (groups 1, 2, and 3: 133.9+/-113.5, 254.0+/-84.6, and 378.7+/-77.6 mmHg, respectively; p<0.0001 vs group 1, p=0.0052 vs group 2), lower peak airway pressure (groups 1, 2, and 3: 28.7+/-6.1, 26.0+/-5.8, and 21.5+/-5.3 mmHg, respectively; p=0.0385 vs group 1), lower wet/dry ratio (groups 1, 2, and 3: 6.74+/-0.78, 5.77+/-0.52, and 4.90+/-0.16, respectively; p=0.0010 vs group 1), and lower myeloperoxidase activity (groups 1, 2, and 3: 0.304+/-0.081, 0.178+/-0.053, and 0.106+/-0.029 DeltaOD/mg/min, respectively; p<0.0001 vs group 1, p=0.0319 vs group 2). No significant differences in arterial PaCO(2) and serum lipid peroxide levels were observed between the three groups.

CONCLUSIONS

Addition of sivelestat to the organ flushing solution ameliorated ischemia-reperfusion injury in a lung transplant model.

Sivelestat, a specific neutrophil elastase inhibitor, suppresses the growth of gastric carcinoma cells by preventing the release of transforming growth factor-alpha

Neutrophil elastase is a neutral serine proteinase produced by polymorphonuclear leukocytes and monocytes/macrophages, especially under surgical stress. In the present study, we investigated whether NE promotes cell growth by activation of EGFR to elucidate whether surgical stress induces tumor proliferation and progression. Furthermore, we examined the antitumor effect of a specific NE inhibitor, sivelestat. Cell growth assays were carried out in vitro and in vivo using TMK-1 gastric cancer cells. TMK-1 cell growth was stimulated to 118% of that of the control cells after 48 h stimulation with 1 microg/mL NE according to an MTT assay. Sivelestat inhibited cell growth to 23.4 and 58.0% of control values at concentrations of 100 and 1,000 microg/mL, respectively. NE rapidly phosphorylated EGFR in only 5 min and triggered the ERK1/2-mitogenic signaling pathway in TMK-1. It was further demonstrated that NE-induced EGFR phosphorylation was transactivated through TGF-alpha, using ELISA. NE increased the cleavage of TGF-alpha from the cell surface 30-fold compared with the cells without treatment. Interestingly, sivelestat significantly reduced NE-induced EGFR phosphorylation and ERK1/2 activation and completely blocked the release of TGF-alpha from the TMK-1 cell surface. In a xenograft study, the addition of ventrotomy as a surgical stress promoted tumor growth. Sivelestat significantly suppressed the tumor growth induced by surgical stress. These results indicate that sivelestat suppresses the growth of gastric cancer cells by inhibiting the release of TGF-alpha stimulated by NE, which often occurs after surgical stresses.

Sivelestat reduces inflammatory mediators and preserves neutrophil deformability during simulated extracorporeal circulation

BACKGROUND

Neutrophil is a major focus in efforts to ameliorate the systemic inflammatory response associated with cardiopulmonary bypass. Neutrophil elastase is a powerful proteolytic enzyme, and plays a pivotal role in the development of the inflammatory response. This study assesses the inhibitory effects of sivelestat, a highly specific neutrophil elastase inhibitor, on elastase levels, cytokine production, and the functional changes of neutrophils in a simulated extracorporeal circulation model.

METHODS

Simulated recirculation was established by recirculating heparinized (3.75 U/mL) human blood for 120 minutes in an oxygenator and a roller pump circuit with and without 100 micromol/L of sivelestat (n = 7 for each group). Neutrophil elastase and interleukin-8 were measured with an enzyme immunoassay. Neutrophil deformability was evaluated by simulated microcapillaries. The neutrophil F-actin and the expression of CD11b and L-selectin were measured by flow cytometry.

RESULTS

Sivelestat reduced both neutrophil elastase levels (p = 0.0006) and interleukin-8 production (p < 0.0001) at 120 minutes of recirculation. Sivelestat also significantly preserved neutrophil deformability (p = 0.017) and reduced F-actin expression (p = 0.0037). The drug did not modulate the changes of CD11b or L-selectin.

CONCLUSIONS

This study suggests that specific elastase inhibition with sivelestat could be a feasible therapeutic strategy for patients undergoing cardiopulmonary bypass to attenuate neutrophil-derived inflammatory response and organ injuries.

Inhibition of neutrophil elastase prevents the development of murine dextran sulfate sodium-induced colitis

BACKGROUND

Neutrophil elastase (NE) is a major secretory product from activated neutrophils and a major contributor to tissue destruction. However, little is known about the pathogenic contribution of NE to ulcerative colitis (UC). This study was designed to investigate the contribution of NE by measuring NE activity in plasma and colonic mucosal tissue from UC patients and a murine acute colitis model, and to elucidate the therapeutic effect of the NE-specific inhibitor ONO-5046.

METHODS

The NE enzyme activities in plasma and colonic mucosal tissue from UC patients were directly measured using an enzyme-substrate reaction. Acute colitis was induced in mice by administration of 1.5% dextran sulfate sodium (DSS) for 5 days. DSS-induced colitis mice were then treated with ONO-5046 (50 mg/kg body weight) intraperitoneally twice a day.

RESULTS

In UC patients, the NE enzyme activity was significantly elevated in both the plasma and colonic mucosal tissue compared with healthy controls. In DSS-induced colitis mice, the NE enzyme activity increased in parallel with the disease development. ONO-5046 showed therapeutic effects in DSS-treated mice by significantly reducing weight loss and histological score. ONO-5046 suppressed the NE enzyme activities in both plasma and culture supernatant of colonic mucosa from DSS-induced colitis mice.

CONCLUSIONS

ONO-5046, a specific NE inhibitor, prevented the development of DSS-induced colitis in mice. NE therefore represents a promising target for the treatment of UC patients.

Effect of a Polymorphonuclear Elastase Inhibitor (Sivelestat Sodium) on Acute Lung Injury After Cardiopulmonary Bypass: Findings of a Double-Blind Randomized Study

PURPOSE

We evaluated the effect of sivelestat sodium (SiV), a novel synthesized polymorphonuclear (PMN) elastase inhibitor, on acute lung injury (ALI) caused by cardiopulmonary bypass (CPB).

METHODS

Fourteen patients who underwent cardiopulmonary surgery using CPB, followed by the development of both systemic inflammatory response syndrome (SIRS) and ALI, were treated with either 0.2 mg/kg per hour SiV (SiV group, n = 7) or saline (control group, n = 7) for 4 days from the time of arrival in the intensive care unit.

RESULTS

The SiV group had a significantly lower ratio of serum PMN elastase and interleukin (IL)-8, a significantly lower ratio of the respiratory index, and a significantly higher ratio of PaO(2)/FiO(2) after 24 h of treatment than the control group.

CONCLUSION

Sivelestat sodium suppressed the production of PMN elastase and IL-8, resulting in improved respiratory function in patients with ALI caused by CPB.

Epithelium-dependent and -independent inhibitory effects of sivelestat, a neutrophil elastase inhibitor, on substance P-induced contraction of airway smooth muscle in lipopolysaccharide-treated guinea-pigs

The underlying mechanism involved in the interaction between neutrophil elastase inhibitors and tachykinins has not been elucidated. In this study we have examined the effects of sivelestat, a neutrophil elastase inhibitor, on the in vitro responses of airways from lipopolysaccharide (LPS)-untreated or -treated guinea-pigs to substance P. Substance P (0.01-30 micromol/l) produced concentration-dependent contractions of both tracheal and bronchial ring preparations of LPS-untreated or -treated guinea-pigs. Responsiveness to substance P in these isolated airway preparations was augmented by either epithelium removal or LPS treatment. In epithelium-intact tracheal ring preparations isolated from LPS-untreated guinea-pigs, sivelestat (100 micromol/l) significantly inhibited substance P-induced contractions. The inhibitory action was markedly attenuated by pretreatment with L-NAME (100 micromol/l) or indomethacin (2 micromol/l), and was almost undetected following removal of the epithelium. On the other hand, in bronchial ring preparations isolated from LPS-untreated guinea-pigs, sivelestat had only a very slight effect on substance P-induced contraction of the epithelium-intact preparation, whereas sivelestat greatly inhibited contraction in epithelium-removed bronchial ring preparations. In LPS-treated guinea-pigs, whether the epithelium was intact or not, sivelestat significantly inhibited the substance P-induced contraction of bronchial ring preparations. Pretreatment with L-NAME (100 micromol/l) or indomethacin (2 micromol/l) did not affect the inhibitory effect of sivelestat in bronchial ring preparations. In conclusion, epithelium removal or LPS treatment induced hyperreactivity to substance P in the guinea-pig airway. Sivelestat caused epithelium-, nitric oxide- and prostaglandin-dependent inhibition of the substance P-induced contraction of isolated guinea-pig tracheal ring preparations. In contrast, the inhibitory effect of sivelestat on substance P-induced contraction of guinea-pig bronchial ring preparations is mediated by epithelium-, nitric oxide- and prostaglandin-independent mechanisms. Sivelestat may be effective in reducing the airway hyperresponsiveness to tachykinins induced by epithelial injury as occurs in LPS-mediated inflammatory lung diseases.

Elastase inhibition reduced death associated with acid aspiration-induced lung injury in hamsters

This study examined whether the specific inhibition of neutrophil elastase by sivelestat sodium hydrate (sivelestat) reduced deaths associated with severe acute lung injury after hydrochloric acid (HCl) aspiration in hamsters. Animals that received a single intratracheal instillation of HCl (0.2 N, 200 microL) time-dependently died by occlusion of their trachea with inflammatory exudate. In a time course study, these animals developed severe lung injury, peaking 12 to 24 h after HCl instillation, as indicated by hemorrhage and a massive increase in the protein concentration of bronchoalveolar lavage fluid. These changes were closely correlated with neutrophil elastase activity in bronchoalveolar lavage fluid. Sivelestat (0.01, 0.1 and 1 mg/kg/h), when intravenously infused during the first 48 h post-HCl instillation, dose-dependently reduced death in HCl-instilled hamsters. In a separate experiment, analysis of bronchoalveolar lavage fluid parameters and partial pressure of arterial oxygen (PaO(2)) 8 h post-HCl instillation showed that sivelestat at 1 mg/kg/h, i.v. significantly improved both bronchoalveolar lavage fluid parameters and PaO(2) levels with evidence of the inhibition of neutrophil elastase activity in bronchoalveolar lavage fluid. These results suggest that neutrophil elastase plays a significant role in this type of severe acute lung injury that leads to death by respiratory failure.

Complement membrane attack complex and hemodynamic changes during human orthotopic liver transplantation

Hemodynamic changes and elevation of intracellular calcium following reperfusion in human liver transplantation occur rapidly and do not match the time course of cytokine expression, therefore, we postulate involvement of other, pre-formed substances, such as complement. We studied 40 adult patients undergoing liver transplantation. Blood was drawn for estimation of C3, C4, C3 degradation product, membrane attack complex, and CH100 levels and elastase (a marker of neutrophil activation) at induction of anesthesia, 5 minutes before reperfusion, 5 minutes and 60 minutes after reperfusion. Cardiac output was measured by thermodilution and systemic vascular resistance was calculated at these same time points. There was a significant rise in C5b-9 membrane attack complex (P =.0012) with a corresponding fall in C3 (P =.0013) and C4 (P =.0002) levels and a rise in C3 degradation product levels (P =.0006). There was no significant change in CH100. These changes very closely followed the hemodynamic changes of a significant fall in systemic vascular resistance index (P =.0024) and increase in cardiac index (P =.0005). Elastase rose from 356 +/- 53 to 557 +/- 40 microg/L (P <.0001). There is complement activation and neutrophil activation at reperfusion in liver transplantation. Dilution alone cannot explain the fall in C3 and C4 levels as there is a corresponding increase in membrane attack complex and C3 degradation product levels with time. As both C3 and C4 are consumed, the classical pathway must be active, though alternative and lectin activated pathways may also be involved. These findings may, at least in part, explain the hemodynamic changes typically seen at reperfusion in liver transplantation.

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.

Suppressive effect of selective cyclooxygenase-2 inhibitor on cytokine release in human neutrophils

To clarify whether a selective cyclooxygenase-2 (COX-2) inhibitor can affect various functions in human peripheral blood neutrophils. For this purpose, the effects of selective COX-2 inhibitors, NS-398 and nimesulide, on the expression of COX-2, PGE2 release and respiratory burst, degranulation and cytokine release in activated neutrophils were examined. Peripheral blood neutrophils were stimulated with formyl-methionyl-leucyl-phenylalanine (FMLP; 100 nM) or opsonized zymosan (OZ; 200 microg/ml). Then, the expression of COX-2 at protein and mRNA levels was detected by Western blot analysis and RT-PCR. The concentration of prostaglandin E2 (PGE2) and cytokines in the culture supernatant of neutrophils was determined using ELISA. Superoxide generation was measured by the cytochrome c reduction method. Elastase activity was measured using a chromogenic substrate assay specific for human neutrophil elastase. FMLP and OZ enhanced PGE2 release through induction of COX-2 protein and mRNA expression. FMLP- or OZ-induced PGE2 release was abolished by the addition of NS-398 or nimesulide; nevertheless, even a high concentration of COX-2 inhibitor did not change FMLP- or OZ-induced expression of COX-2 at message and protein levels. Although FMLP- or OZ-induced superoxide generation and elastase release were not affected by the addition of COX-2 inhibitor, cytokine release such as interleukin (IL)-1beta, IL-6 and IL-8 was significantly inhibited by high concentration of COX-2 inhibitor, but tumor necrosis factor-alpha (TNF-alpha) was partially attenuated. These studies showed that selective COX-2 inhibitors, NS-398 and nimesulide, suppressed PGE2 and proinflammatory cytokine release in activated neutrophils. These results suggest that selective COX-2 inhibitors may contribute to resolution of acute inflammation through the reduction of inflammatory cytokine release in activated neutrophils.

[Pharmacological profile of a specific neutrophil elastase inhibitor, Sivelestat sodium hydrate]

Imbalance between neutrophil elastase (NE) and its endogenous protease inhibitors has been considered to be one of possible mechanisms by which NE causes lung tissue destruction. It has been shown that the amount and/or activity of NE is increased in blood and bronchoalveolar lavage fluid in patients with acute lung injury. Accordingly, animals undergoing acute lung injury have increased NE activity such as in blood and bronchoalveolar lavage fluid. Sivelestat sodium hydrate (Sivelestat) is a synthetic inhibitor of NE with highly specificity to NE. Many studies have indicated that Sivelestat treatment improves inflammatory and edematous changes of lungs and survival as well as increased NE activity in several animal models of acute lung injury. Clinical studies have demonstrated that Sivelestat improves this injury that is associated with systemic inflammatory response syndrome. As compared with endogenous protease inhibitors that have high molecular mass, Sivelestat, a synthetic and low molecular weight elastase inhibitor, may be delivered to the inflammatory sites more easily and effectively and is considred to improve typical symptoms of acute lung injury. Clinical use of Sivelestat would further clarify the usefulness of this compound in clinical acute lung injury.

Effect of plant Kunitz inhibitors from Bauhinia bauhinioides and Bauhinia rufa on pulmonary edema caused by activated neutrophils

Mediators released from polymorphonuclear neutrophils, in particular elastase, are known to induce acute edematous lung injury. In this study we show that the pulmonary edema in isolated perfused rabbit lungs caused by activated neutrophils via release of elastase is significantly decreased by the Kunitz-type Inhibitor BbCI (10(-5) M) from Bauhinia bauhinoides to the same degree as by eglin C (10(-5) M) from Hirudo medicinalis, which was used as a reference. The highly homologous proteinase inhibitor BrPI (10(-5) M) from Bauhinia rufa, however, did not reduce edema formation. The major difference between these inhibitors is the much higher Ki value of BrPI (Ki = 38 nM) for elastase compared to BbCI (Ki = 5.3 nM) and eglin C (Ki = 0.2 nM), respectively. Elastase liberation from activated PMNs was not influenced by the inhibitors. Our results indicate that BbCI can be a useful tool to study the role of neutrophil elastase in pathophysiological processes.

Proteases and lung injury

OBJECTIVE

Acute respiratory distress syndrome (ARDS) represents an inflammatory process that is initiated by diverse systemic and/or pulmonary insults, resulting in a clinical syndrome of severe respiratory distress and refractory hypoxemia. Neutrophils and their cytotoxic products, including oxidants and proteases, such as elastase, have been implicated as playing a key role in the pathophysiology of ARDS. This article reviews some of the physiologic actions of proteases, specifically elastase, the evidence for neutrophil elastase involvement in ARDS, and the potential therapeutic use of neutrophil elastase inhibitors in lung injury.

DATA SOURCE

A review of published literature (original articles and reviews) in English from 1965 to 2002.

CONCLUSION

Although the data support a key role for neutrophil elastase in the pathogenesis of ARDS, further study is needed to fully define the actions of neutrophil elastase, and how these actions affect host functions, before we can exploit this knowledge for therapeutic benefit.

The role of neutrophil elastase in acute lung injury

Beside its physiological function as a powerful host defense, neutrophil elastase is also known as one of the most destructive enzymes in the body. Current notion holds that neutrophil elastase is able to escape from regulation by multiple protease inhibitors at inflammatory sites. Once unregulated, this enzyme disturbs the function of the lung permeability barrier and induces the release of pro-inflammatory cytokines. These actions then cause symptoms that are typical in the pathophysiology of acute lung injury. In this article, we review recent progress in the understanding of the physiological activity of neutrophil elastase and its role in acute lung injury. Evidence in this review that supports the involvement of neutrophil elastase in the pathophysiology of acute lung injury includes: (1) neutrophil elastase levels are increased in both clinical and animal models of acute lung injury; (2) topical or systemic administration of neutrophil elastase produces typical symptoms of acute lung injury both in vitro and in vivo; and (3) inhibition of increased neutrophil elastase activity reduces symptoms of acute lung injury in animal models. A greater understanding of the role of this enzyme in the pathophysiology of acute lung injury will lead to better treatments for this complicated disease.

Neutrophil elastase and acute lung injury: prospects for sivelestat and other neutrophil elastase inhibitors as therapeutics

OBJECTIVES

To review the evidence and rationale that suggest that neutrophil elastase (NE) may contribute to the development of acute lung injury (ALI) and the acute respiratory distress syndrome. To review selected preliminary data regarding the effectiveness of NE inhibition in animals, in in vitro models, and in patients with ALI.

DATA SOURCES

The published literature and observations provided by Ono Pharmaceutical and Eli Lilly investigators and their colleagues.

DATA SUMMARY

Taken en toto, the data suggest that NE could contribute to ALI and endothelial cell injury that is relevant to ALI. Moreover, the toxic effects of NE are greatly enhanced by increased oxidative stress, which commonly occurs in patients with ALI. In addition to neutrophils, xanthine oxidase, a constituent of endothelial cells, is a potential source of oxidative stress in ALI; xanthine oxidase-derived oxidants enhance NE toxicity in in vivo, isolated lung, and in vitro endothelial cell test systems. Not surprisingly, endogenous nonoxidatively sensitive NE inhibitors (e.g., eglin C) are more effective in combating the detrimental effects of NE than oxidatively sensitive NE inhibitors (e.g., alpha-1-proteinase inhibitor). In addition, a synthetic NE inhibitor, sivelestat (ONO-5046 and LY544349), is effective in reducing measures of inflammation and injury in multiple animal models of ALI. In a trial of ALI patients with systemic inflammatory response syndrome, conducted in Japan by Ono Pharmaceutical scientists, sivelestat treatment improved the investigator assessment of global improvement and the percentages of patients who were removed from ventilators and transferred out of the intensive care unit.

CONCLUSIONS

Further study of the role of NE inhibition as a treatment for ALI is warranted. Additional clinical and preclinical studies with sivelestat and various other NE inhibitors should not only clarify the clinical potential of this intervention strategy, but also better define the activities of NE in inflammatory disorders such as ALI and multiple organ failure.