A neutrophil elastase inhibitor, sivelestat, improves leukocyte deformability in patients with acute lung injury

Trypsin is inhibited by phytocompounds liquiritin and terpinen-4-ol from the herb Glycyrrhiza glabra: in vitro and in silico studies

Serine proteases are a class of hydrolytic enzymes involved in various physiological functions like digestion, coagulation, fibrinolysis and immunity. The present study evaluates the serine protease inhibitory potential of phytochemicals liquiritin and terpinen-4-ol present in the herb Glycyrrhiza glabra L. using trypsin as the model enzyme. In silico studies showed that both the compounds have a significant binding affinity towards trypsin with a binding energy of -26.66 kcal/mol and -19.79 kcal/mol for liquiritin and terpinen-4-ol, respectively. Their binding affinity was confirmed through in vitro enzyme inhibition assays. The mode of inhibition was found to be uncompetitive. In order to explain the mode of inhibition, docking of the ligands to the enzyme-substrate complex was also done and binding energy was calculated after MD simulation. The energy values showed that the binding affinities of these compounds towards the enzyme substrate complex are more than that towards the enzyme alone. This explains the uncompetitive mode of inhibition.Communicated by Ramaswamy H. Sarma.

Investigational pharmacological agents for the treatment of ARDS

INTRODUCTION

Acute Respiratory Distress Syndrome (ARDS) is a heterogeneous form of lung injury with severe hypoxemia and bilateral infiltrates after an inciting event that results in diffuse lung inflammation with a high mortality rate. While research in COVID-related ARDS has resulted in several pharmacotherapeutic agents that have undergone successful investigation, non-COVID ARDS studies have not resulted in many widely accepted pharmacotherapeutic agents despite exhaustive research.

AREAS COVERED

The aim of this review is to discuss adjuvant pharmacotherapies targeting non-COVID Acute Lung Injury (ALI)/ARDS and novel therapeutics in COVID associated ALI/ARDS. In ARDS, variable data may support selective use of neuromuscular blocking agents, corticosteroids and neutrophil elastase inhibitors, but are not yet universally used. COVID-ALI/ARDS has data supporting the use of IL-6 monoclonal antibodies, corticosteroids, and JAK inhibitor therapy.

EXPERT OPINION

Although ALI/ARDS modifying pharmacological agents have been identified in COVID-related disease, the data in non-COVID ALI/ARDS has been less compelling. The increased use of more specific molecular phenotyping based on physiologic parameters and biomarkers, will ensure equipoise between groups, and will likely allow more precision in confirming pharmacological agent efficacy in future studies.

The Role of Neutrophils and Neutrophil Elastase in Pneumococcal Pneumonia

Streptococcus pneumoniae, also known as pneumococcus, is a Gram-positive diplococcus and a major human pathogen. This bacterium is a leading cause of bacterial pneumonia, otitis media, meningitis, and septicemia, and is a major cause of morbidity and mortality worldwide. To date, studies on S. pneumoniae have mainly focused on the role of its virulence factors including toxins, cell surface proteins, and capsules. However, accumulating evidence indicates that in addition to these studies, knowledge of host factors and host-pathogen interactions is essential for understanding the pathogenesis of pneumococcal diseases. Recent studies have demonstrated that neutrophil accumulation, which is generally considered to play a critical role in host defense during bacterial infections, can significantly contribute to lung injury and immune subversion, leading to pneumococcal invasion of the bloodstream. Here, we review bacterial and host factors, focusing on the role of neutrophils and their elastase, which contribute to the progression of pneumococcal pneumonia.

Neutrophil Elastase Inhibitor Sivelestat Attenuates Myocardial Injury after Cardioplegic Arrest in Rat Hearts

Purpose: Sivelestat, a neutrophil elastase inhibitor, attenuates global ischemia-induced myocardial damage and coronary endothelial dysfunction. Here, we investigated whether sivelestat exerts the cardioprotective effects against cardioplegic arrest in rat hearts.

Methods: Isolated Langendorff-perfused rat hearts were randomly allocated to three groups and subjected to 2-min infusions with St. Thomas’ Hospital cardioplegic solution No. 2 (STH2) and 30-min global ischemia followed by 60-min reperfusion as follows: (i) control (STH2 treatment only), (ii) sivelestat (19 μmol/L) infusion for the first 10 min of reperfusion, and (iii) sivelestat (19 μmol/L) infusion for 10 min before ischemia and for the first 10 min of reperfusion. Left ventricular developed pressure (LVDP) recovery and troponin T leakage were measured at the end of reperfusion. Coronary flow response to acetylcholine (ACh) was assessed.

Results: Single and multiple doses of sivelestat significantly improved LVDP recovery (69 ± 15 and 69 ± 14 vs 48 ± 15 [control]; p <0.05) and decreased troponin T leakage (0.4 ± 0.3 and 0.7 ± 0.5 vs 1.7 ± 0.6 [control]; p <0.05). Multiple doses of sivelestat significantly improved coronary flow response to ACh (121 ± 9 vs 105 ± 4; p <0.05).

Conclusions: Addition of sivelestat to STH2 attenuates myocardial injury after cardioplegic arrest in rat hearts. This cardioprotective effect was achieved even when sivelestat was administered during early reperfusion.

Neutrophil elastase inhibitor purification strategy from cowpea seeds

Serine proteases and its inhibitors are involved in physiological process and its deregulation lead to various diseases like Chronic Obstructive Pulmonary Disease (COPD), pulmonary emphysema, skin diseases, atherosclerosis, coagulation diseases, cancer, inflammatory diseases, neuronal disorders and other diseases. Serine protease inhibitors have been described in many species, as well as in plants, including cowpea beans (Vigna unguiculata (L.) Walp). Here, we purified and characterized a protease inhibitor, named VuEI (Vigna unguiculata elastase inhibitor), from Vigna unguiculata, with inhibitory activity against HNE (human neutrophil elastase) and chymotrypsin but has no inhibitory activity against trypsin and thrombin. VuEI was obtained by alkaline protein extraction followed by three different chromatographic steps in sequence. First, an ion exchange chromatography using Hitrap Q column was employed, followed by two reversed-phase chromatography using Source15RPC and ACE18 columns. The molecular mass of VuEI was estimated in 10.99 kDa by MALDI-TOF mass spectrometry. The dissociation constant (Ki) to HNE was 9 pM. These data indicate that VuEI is a potent inhibitor of human neutrophil elastase, besides to inhibit chymotrypsin.

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.

The leukocyte-stiffening property of plasma in early acute respiratory distress syndrome (ARDS) revealed by a microfluidic single-cell study: the role of cytokines and protection with antibodies

Background

Leukocyte-mediated pulmonary inflammation is a key pathophysiological mechanism involved in acute respiratory distress syndrome (ARDS). Massive sequestration of leukocytes in the pulmonary microvasculature is a major triggering event of the syndrome. We therefore investigated the potential role of leukocyte stiffness and adhesiveness in the sequestration of leukocytes in microvessels. 

Methods

This study was based on in vitro microfluidic assays using patient sera. Cell stiffness was assessed by measuring the entry time (ET) of a single cell into a microchannel with a 6 × 9–μm cross-section under a constant pressure drop (ΔP = 160 Pa). Primary neutrophils and monocytes, as well as the monocytic THP-1 cell line, were used. Cellular adhesiveness to human umbilical vein endothelial cells was examined using the laminar flow chamber method. We compared the properties of cells incubated with the sera of healthy volunteers (n = 5), patients presenting with acute cardiogenic pulmonary edema (ACPE; n = 6), and patients with ARDS (n = 22), of whom 13 were classified as having moderate to severe disease and the remaining 9 as having mild disease. 

Results

Rapid and strong stiffening of primary neutrophils and monocytes was induced within 30 minutes (mean ET >50 seconds) by sera from the ARDS group compared with both the healthy subjects and the ACPE groups (mean ET <1 second) (p < 0.05). Systematic measurements with the THP-1 cell line allowed for the establishment of a strong correlation between stiffening and the severity of respiratory status (mean ET 0.82 ± 0.08 seconds for healthy subjects, 1.6 ± 1.0 seconds for ACPE groups, 10.5 ± 6.1 seconds for mild ARDS, and 20.0 ± 8.1 seconds for moderate to severe ARDS; p < 0.05). Stiffening correlated with the cytokines interleukin IL-1β, IL-8, tumor necrosis factor TNF-α, and IL-10 but not with interferon-γ, transforming growth factor-β, IL-6, or IL-17. Strong stiffening was induced by IL-1β, IL-8, and TNF-α but not by IL-10, and incubations with sera and blocking antibodies against IL-1β, IL-8, or TNF-α significantly diminished the stiffening effect of serum. In contrast, the measurements of integrin expression (CD11b, CD11a, CD18, CD49d) and leukocyte–endothelium adhesion showed a weak and slow response after incubation with the sera of patients with ARDS (several hours), suggesting a lesser role of leukocyte adhesiveness compared with leukocyte stiffness in early ARDS. 

Conclusions

The leukocyte stiffening induced by cytokines in the sera of patients might play a role in the sequestration of leukocytes in the lung capillary beds during early ARDS. The inhibition of leukocyte stiffening with blocking antibodies might inspire future therapeutic strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1157-5) contains supplementary material, which is available to authorized users.

Sivelestat prevents cytoskeletal rearrangements in neutrophils resulting from lung re-expansion following one-lung ventilation during thoracic surgery

Patients undergoing lobectomy are at risk of developing acute lung injury resulting from one-lung ventilation (OLV) during surgery. We investigated the morphological and functional behavior of neutrophils in patients who underwent lobectomy and assessed the ability of sivelestat to inhibit neutrophil activity. This was a blinded randomized study. Sixteen patients who underwent lobectomy were given intravenous sivelestat (n = 8) or intravenous saline (n = 8). We studied the cytoskeletal rearrangements of circulating neutrophils by determining the localization of filamentous actin (F-actin). Pulmonary oxygenation was evaluated by measuring the partial pressure of arterial oxygen. We found that the number of circulating, F-actin-rimmed neutrophils increased during OLV and after lung re-expansion. Our results suggest that, in addition to the surgical procedure and OLV, re-expansion of the remaining lung after lobectomy increases the neutrophil activation levels. Furthermore, administration of sivelestat limited neutrophil activation and improved pulmonary oxygenation in our patients.

Leukocyte deformability is a novel biomarker to reflect sepsis-induced disseminated intravascular coagulation

Aim

Sepsis-induced disseminated intravascular coagulopathy is associated with a high mortality rate. The function and deformability of polymorphonuclear leukocytes change in patients with sepsis. The goal of this study was to characterize the changes in polymorphonuclear leukocyte deformability in patients with sepsis-induced disseminated intravascular coagulopathy and to evaluate the relationship between the severity of disseminated intravascular coagulopathy and the deformability of polymorphonuclear leukocytes.

Methods

Thirty-five patients with sepsis-induced disseminated intravascular coagulopathy at our department were enrolled in this study. These patients were diagnosed with severe sepsis and an acute disseminated intravascular coagulopathy score ≥ 4. Blood samples were obtained from these patients on days 1, 3, and 7. Polymorphonuclear leukocyte deformability was measured with a microchannel flow analyzer, and polymorphonuclear leukocyte activity, represented as CD11b, was measured by flow cytometry. In contrast, 14 patients who fulfilled with sepsis criteria but without complicated disseminated intravascular coagulopathy were also entered in this study.

Results

In patients with sepsis-induced disseminated intravascular coagulopathy, there was a significant correlation between their Japanese Association for Acute Medicine disseminated intravascular coagulopathy score and polymorphonuclear leukocyte deformability, and CD11b expression. Polymorphonuclear leukocytes became more stiffened and CD11b expression was higher in patients with sepsis-induced disseminated intravascular coagulopathy compared to patients without the condition.

Conclusion

Polymorphonuclear leukocyte deformability correlated with the severity of sepsis-induced disseminated intravascular coagulopathy and the response to treatment.

Innate immune responses and neuroepithelial degeneration and regeneration in the mouse olfactory mucosa induced by intranasal administration of Poly(I:C)

The pathogenesis of postviral olfactory disorder (PVOD) has not been fully elucidated. We investigated morphological changes and innate immune responses in the mouse olfactory mucosa induced by intranasal administration of polyinosinic-polycytidylic acid [Poly(I:C)], a synthetic analog of viral double-stranded RNA. Mice received three administrations of saline with or without Poly(I:C), once every 24 h. The olfactory mucosa was harvested at various intervals after the first administration (8 h, 3, 9 and 24 days). In the Poly(I:C) group, the number of apoptotic cells in the olfactory neuroepithelium had increased at 8 h. At 9 days, the olfactory neuroepithelium had severely degenerated and behavioral tests demonstrated that the mice showed signs of olfactory deterioration. At 24 days, the structure of the neuroepithelium had regenerated almost completely. Regarding the innate immune responses, many neutrophils had infiltrated the olfactory neuroepithelium at 8 h and had exuded into the nasal cavity by 3 days. Macrophages had also infiltrated the olfactory neuroepithelium at 8 h although to a lesser extent, but they still remained in the neuroepithelium at 24 days. Poly(I:C)-induced neuroepithelial damage was significantly inhibited by a neutrophil elastase inhibitor and was suppressed in neutropenic model mice. These findings suggest that the secondary damage caused by the neutrophil-mediated innate immune response plays an important role in the pathogenesis of PVOD.

Direct interaction of ONO-5046 with human neutrophil elastase through ¹H NMR and molecular docking

Human neutrophil elastase (HNE) has been implicated as a major contributor in the pathogenesis of diseases, such as pulmonary emphysema, acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and other inflammatory diseases. Therefore, searching for appropriate and potential human neutrophil elastase inhibitors (HNEI) that would restore the balance between the free enzyme and the endogenous inhibitors would be of therapeutic interest. ONO-5046 is the first specific HNEI to improve respiratory function and protect lung tissues against various lung injuries. However, the mechanism of ONO-5046 to HNE is still unclear. In this study, the binding properties of ONO-5046 were investigated through (1)H NMR, molecular docking, and bioassay methods to understand the effect of ONO-5046 to HNE. The proton spin-lattice relaxation rate and molecular rotational correlation time results indicated that ONO-5046 has higher affinity with HNE. The molecular docking study showed that ONO-5046 is perfectly matched for the primary enzyme specificity pocket (S1 pocket), and is tightly bound to this pocket of HNE through hydrophobic and hydrogen bonding interactions. The results of both methods were validated through analysis of the HNE inhibitory activity bioassay of ONO-5046 with an IC(50) value of 87.05 nM. Our data suggested that ONO-5046 could bind to HNE through direct interaction, and that molecular docking and NMR methods are valid approaches to survey new HNEI.

Protective effect of an elastase inhibitor in a neuromyelitis optica-like disease driven by a peptide of myelin oligodendroglial glycoprotein

BACKGROUND

The pathology of neuromyelitis optica (NMO), in contrast to multiple sclerosis, comprises granulocyte infiltrates along extensive lengths of spinal cord, as well as optic nerve. Furthermore, IFN-β treatment worsens NMO. We recently found that experimental autoimmune encephalomyelitis (EAE) induced with Th17 cells is exacerbated by IFN-β, in contrast to disease induced with Th1 where treatment attenuated symptoms.

OBJECTIVE

This study demonstrates the similarities between NMO and Th17 EAE and how neutrophils mediate pathology in Th17 disease.

METHODS

Levels of blood biomarkers in NMO were assessed by Luminex and ELISA. Effects of IFN-β on neutrophils were assessed by culture assays and immunofluorescence. EAE was induced by transfer of myelin-specific Th1 or Th17 cells and treated with Sivelestat sodium hydrate, a neutrophil elastase inhibitor.

RESULTS

We show Th17 cytokines, granulocyte chemokines, type 1 interferon and neutrophil elastase are elevated in patients with definitive NMO. In culture, we find that IFN-β stimulates neutrophils to release neutrophil elastase. In Th17 EAE, we demonstrate neutrophilic infiltration in the optic nerve and spinal cord which was not present in Th1 EAE. Blockade of neutrophil elastase with Sivelestat had efficacy in Th17 EAE but not Th1 EAE.

CONCLUSIONS

The similarities between Th17 EAE and NMO indicate that this model represents several aspects of NMO. Neutrophils are critical in the pathologies of both Th17-EAE and NMO, and therefore blockade of neutrophil elastase is a promising target in treating NMO.

Lung injury following acute kidney injury: kidney-lung crosstalk

The mortality of acute kidney injury (AKI) remains unacceptably high, especially associated with acute respiratory failure. Lung injury complicated with AKI was previously considered as "uremic lung", which is characterized by volume overload and increased vascular permeability. New experimental data using rodent models of renal ischemia-reperfusion and bilateral nephrectomy have emerged recently focusing on kidney-lung crosstalk in AKI, and have highlighted the pathophysiological significance of increased cytokine concentration, enhanced inflammatory responses, and neutrophil activation. In this review, we outline the history of uremic lung and acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), the epidemiological data on the synergistic effect of AKI and lung injury on mortality, and recent basic research which has identified possible pathways in AKI-induced lung injury. These findings will enable us to develop new therapeutic strategies against lung injury associated with AKI and improve the outcomes of critically ill patients in intensive care units.

Neutrophil elastase inhibitor restores gut ischemia reperfusion-induced impairment of gut immunity with reduced plasma interleukin-6 concentrations in mice

BACKGROUND AND PURPOSE

Gut-associated lymphoid tissue (GALT) is regarded as central mucosa-associated lymphoid tissue that influences systemic mucosal immunity. Our previous study revealed that gut ischemia and reperfusion (I/R) reduces GALT lymphocyte numbers. Because gut hypoperfusion frequently occurs in trauma, shock, and surgery patients, establishment of a therapeutic method to preserve GALT mass after gut I/R may be important for the prevention of infections. We examined the effects of sivelestat sodium hydrate, a selective inhibitor of neutrophil elastase, on GALT mass and plasma cytokine concentrations in a murine gut I/R model.

METHODS

Seventy male ICR mice were randomized to the control (n = 34) or the sivelestat (n = 36) group. After intravenous cannulation of the animals, the superior mesenteric artery was occluded for 60 min. After reperfusion, physiologic saline or sivelestat 5 mg/kg hourly was infused for 24 h. Sixteen mice in the control and 22 in the sivelestat group were alive at 24 h. Twenty-six mice (n = 13 in each group) were chosen randomly for harvest of the small intestine. Lymphocytes from Peyer patches (PP), the intraepithelial space (IE), and the lamina propria (LP) were counted; and their phenotypes (αβT-cell receptor (TCR), γδTCR, CD4, CD8, B cell) were determined by flow cytometry. Cytokine concentrations (interleukin [IL]-6, IL-1β, IL-10) in the plasma and bronchoalveolar lavage fluid were measured by enzyme-linked immunosorbent assay.

RESULTS

Sivelestat treatment did not improve survival but increased PP and IE lymphocyte numbers significantly and reduced the LP CD8(+) cell percentage and plasma IL-6 concentration compared with controls. There were no significant differences between the two groups in other cell phenotypes or cytokine concentrations.

CONCLUSION

Sivelestat treatment after gut I/R may be useful for maintaining gut immunity and preventing systemic inflammatory responses.

Immunosuppression following surgical and traumatic injury

Severe sepsis and organ failure are still the major causes of postoperative morbidity and mortality after major hepatobiliary pancreatic surgery. Despite recent progress in understanding the immune conditions of abdominal sepsis, the postoperative incidence of septic complications after major visceral surgery remains high. This review focuses on the clinical and immunological parameters that determine the risk of the development and lethal outcome of postoperative septic complication following major surgery and trauma. A review of the literature indicates that surgical and traumatic injury profoundly affects the innate and adaptive immune responses, and that a marked suppression in cell-mediated immunity following an excessive inflammatory response appears to be responsible for the increased susceptibility to subsequent sepsis. The innate and adaptive immune responses are initiated and modulated by pathogen-associated molecular-pattern molecules and by damage-associated molecular-pattern molecules through the pattern-recognition receptors. Suppression of cell-mediated immunity may be caused by multifaceted cytokine/inhibitor profiles in the circulation and other compartments of the host, excessive activation and dysregulated recruitment of polymorphonuclear neutrophils, induction of alternatively activated or regulatory macrophages that have anti-inflammatory properties, a shift in the T-helper (Th)1/Th2 balance toward Th2, appearance of regulatory T cells, which are potent suppressors of the innate and adaptive immune system, and lymphocyte apoptosis in patients with sepsis. Recent basic and clinical studies have elucidated the functional effects of surgical and traumatic injury on the immune system. The research studies of interest may in future aid in the selection of appropriate therapeutic protocols.

A3 and P2Y2 receptors control the recruitment of neutrophils to the lungs in a mouse model of sepsis

We have recently shown that A3 adenosine receptors and P2Y2 purinergic receptors play an important role in neutrophil chemotaxis. Chemotaxis of neutrophils to sites of infections is critical for immune defense. However, excessive accumulation of neutrophils in the lungs can cause acute lung tissue damage. Here we assessed the role of A3 and P2Y2 receptors in neutrophil sequestration to the lungs in a mouse model of sepsis. Sepsis was induced by cecal ligation and puncture (CLP) using adult male C57BL/6J mice (wild type [WT]), homozygous A3 receptor knockout (A3KO) mice, and P2Y2 receptor knockout (P2Y2KO) mice. Animals were killed 2, 4, 6, or 8 h after CLP, and peritoneal lavage fluid and blood were collected. Lungs were removed, and neutrophil infiltration was evaluated using elastase as a marker. Leukocyte and bacterial counts in peritoneal lavage fluid and blood samples were determined. Survival after sepsis was determined in a separate group. Leukocyte counts in the peritoneum were lower in A3KO and P2Y2KO mice than in WT mice. Conversely, initial leukocyte counts in the peripheral blood were higher in KO mice than in WT mice. Neutrophil sequestration to the lungs reached a maximum 2 h after CLP and remained significantly higher in WT mice compared with A3KO and P2Y2KO mice (P < 0.001). Survival after 24 h was significantly lower in WT mice (37.5%) than in A3KO or P2Y2KO mice (82.5%; P < 0.05). These data suggest that A3 and P2Y2 receptors are involved in the influx of neutrophils into the lungs after sepsis. Thus, pharmaceutical approaches that target these receptors might be useful to control acute lung tissue injury in sepsis.

Analyzing cell mechanics in hematologic diseases with microfluidic biophysical flow cytometry

Pathological processes in hematologic diseases originate at the single-cell level, often making measurements on individual cells more clinically relevant than population averages from bulk analysis. For this reason, flow cytometry has been an effective tool for single-cell analysis of properties using light scattering and fluorescence labeling. However, conventional flow cytometry cannot measure cell mechanical properties, alterations of which contribute to the pathophysiology of hematologic diseases such as sepsis, diabetic retinopathy, and sickle cell anemia. Here we present a high-throughput microfluidics-based 'biophysical' flow cytometry technique that measures single-cell transit times of blood cell populations passing through in vitro capillary networks. To demonstrate clinical relevance, we use this technique to characterize biophysical changes in two model disease states in which mechanical properties of cells are thought to lead to microvascular obstruction: (i) sepsis, a process in which inflammatory mediators in the bloodstream activate neutrophils and (ii) leukostasis, an often fatal and poorly understood complication of acute leukemia. Using patient samples, we show that cell transit time through and occlusion of microfluidic channels is increased for both disease states compared to control samples, and we find that mechanical heterogeneity of blood cell populations is a better predictor of microvascular obstruction than average properties. Inflammatory mediators involved in sepsis were observed to significantly affect the shape and magnitude of the neutrophil transit time population distribution. Altered properties of leukemia cell subpopulations, rather than of the population as a whole, were found to correlate with symptoms of leukostasis in patients-a new result that may be useful for guiding leukemia therapy. By treating cells with drugs that affect the cytoskeleton, we also demonstrate that their transit times could be significantly reduced. Biophysical flow cytometry offers a low-cost and high-throughput diagnostic and drug discovery platform for hematologic diseases that affect microcirculatory flow.

Neutrophil elastase inhibitor (sivelestat) attenuates subsequent ventilator-induced lung injury in mice

Mechanical ventilation can paradoxically cause acute lung injury, which is termed ventilator-induced lung injury. Neutrophil recruitment and neutrophil elastase release play a central role in the pathogenesis of ventilator-induced lung injury including cell damage, extracellular matrix degradation and alveolar-capillary hyperpermeability. We therefore speculated that neutrophil elastase inhibition ameliorates ventilator-induced lung injury. Anesthetized C57/BL6 mice received mechanical ventilation with a high tidal volume (V(T); 20 ml/kg) for 4 h. The neutrophil elastase inhibitor (sivelestat, 100 mg/kg) or saline was given intraperitoneally (i.p.) 30 min before ventilation. Sivelestat completely inhibited both neutrophil elastase and myeloperoxidase activities that were increased by ventilation, and attenuated the histopathological degree of lung damage, neutrophil accumulation and lung water content, as well as the concentration of macrophage inflammatory protein (MIP)-2, interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha in bronchoalveolar lavage fluid and serum. Moreover, mechanical ventilation increased the phosphorylation of c-Jun NH2-terminal kinase (JNK) and the expression of early growth response gene-1 (Egr-1) mRNA, and these increases were also recovered by sivelestat. The terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) staining revealed apoptotic cells mainly in alveolar epithelial cells and their numbers corresponded to histological damage. These data suggested that sivelestat could protect against ventilator-induced lung injury by suppressing apoptotic responses through mechanical stress-induced cell signaling in addition to inhibiting neutrophil chemotaxis.

Systemic macrophage and neutrophil destruction by secondary necrosis induced by a bacterial exotoxin in a Gram-negative septicaemia

Bacterial modulation of phagocyte cell death is an emerging theme in pathogenesis. Here we describe the systemic destruction of macrophages and neutrophils by the Gram-negative Photobacterium damselae ssp. piscicida (Phdp) in fish pasteurellosis, a deadly systemic infection. Following experimental inoculation, Phdp spreads by bacteraemia and colonizes the organs, producing a septicaemic infection, and secretes the apoptogenic exotoxin AIP56 which is systemically disseminated. In experimental and natural pasteurellosis, destruction of macrophages and neutrophils by secondary necrosis following caspase-3-associated apoptosis was seen predominantly in the spleen, head kidney and gut lamina propria. Identical phagocyte destruction occurred after injection of rAIP56, but not of heat-inactivated rAIP56, or AIP56-negative Phdp strains, indicating that AIP56 is responsible for phagocyte destruction occurring in pasteurellosis. Active caspase-3 and active neutrophil elastase are present in the blood in advanced infection, indicating that phagocyte lysis by secondary necrosis is accompanied by release of tissue-damaging molecules. The AIP56-induced lysis of phagocytes represents a very efficient, self-amplifying etiopathogenic mechanism, because it results in two effects that operate in concert against the host, namely, evasion of the pathogen from a crucial defence mechanism through the destruction of both professional phagocytes, and release of tissue-damaging molecules. The induction by a bacterial exotoxin of in vivo systemic lysis of both professional phagocytes by secondary necrosis, now described for the first time, may represent an overlooked etiopathogenic mechanism operating in other infections of vertebrates.

Neutrophil elastase inhibitor prevents endotoxin-induced liver injury following experimental partial hepatectomy

Background

During endotoxaemia, neutrophils activated by inflammatory cytokines release reactive oxygen species and neutrophil elastase, resulting in hepatic necrosis and dysfunction. This study investigated the possible mechanism underlying the protective effect of sivelestat, a neutrophil elastase inhibitor, on endotoxin-induced liver injury following partial hepatectomy.

Methods

Lipopolysaccharide (LPS) was administered intravenously to male Sprague–Dawley rats 48 h after 70 per cent hepatectomy. Sivelestat or normal saline was given intravenously before LPS administration,

Results

Treatment with sivelestat significantly improved the survival rate. Sivelestat prevented increases in the concentration of serum enzymes and total bilirubin related to liver injury. Levels of inflammatory cytokines in serum and liver tissue were significantly lower in the sivelestat-treated group than in the control group. The degree of neutrophil infiltration, necrosis and apoptosis in the remnant liver was significantly decreased in sivelestat-treated rats. Sivelestat pretreatment inhibited the activation of nuclear factor (NF) κB, caspase 3 and 8 activities, and cytochrome c release.

Conclusion

Sivelestat prevents LPS-induced liver injury by inhibition of NF-κB activation and apoptosis.

Response of serum interleukin-6 in patients undergoing elective surgery of varying severity

1. Recent studies have suggested that interleukin-6 is a major mediator of the acute-phase protein response in man. The aim of the present study was to investigate the relationships between the response of serum interleukin-6 to surgery, the type of surgical procedure performed and the response of serum C-reactive protein. 2. Timed venous blood samples were taken from 26 patients in five broad surgical categories (minor surgery, cholecystectomy, hip replacement, colorectal surgery and major vascular surgery). C-reactive protein and interleukin-6 were measured in each sample. 3. Serum interleukin-6 rose within 2-4 h of incision in all patients and the magnitude of the response differed among the various surgical groups. The response of interleukin-6 correlated (r = 0.80, P less than 0.001) with the duration of surgery. In contrast, serum C-reactive protein was not detectable after minor surgery (less than 10 mg/l) and the response of C-reactive protein did not differ among the more major surgical groups. The response of interleukin-6 showed a weak, but significant, correlation with the response of C-reactive protein (r = 0.67, P less than 0.001). 4. We conclude that serum interleukin-6 is a sensitive, early marker of tissue damage. In general, the greater the surgical trauma, the greater the response of serum interleukin-6 and the greater the peak serum concentration of interleukin-6. Our results are consistent with a role for interleukin-6 in the induction of C-reactive protein synthesis.