Protective effect of recombinant neutrophil elastase inhibitor (R-020) on sepsis-induced organ injury in rat

Absence of DCIR1 reduces the mortality rate of endotoxemic hepatitis in mice

Dendritic cell immunoreceptor (DCIR) is a C-type lectin with an immunoreceptor tyrosine-based inhibitory motif (ITIM). Mice lacking DCIR1 (Dcir1^-/- mice) show higher susceptibility to chronic arthritis with increasing age, suggesting that DCIR1 is involved in immune modulation via its ITIM. However, the role of DCIR1 in acute immune responses is not clear. In this study, we explored its role in acute experimental hepatitis. Upon injection of d-galactosamine and lipopolysaccharide, Dcir1^-/- mice showed decreased mortality rates and serum levels of alanine aminotransferase. In early onset hepatitis, serum levels of TNF-α, which primarily cause inflammation and hepatocyte apoptosis, were significantly lower in Dcir1^-/- mice than in WT mice. In the liver of Dcir1^-/- mice, influx of neutrophils and other leukocytes decreased. Consistently, the levels of neutrophil-chemoattractant chemokine CXCL1/KC, but not CXCL2/MIP-2, were lower in Dcir1^-/- mice than in WT mice. However, chemotaxis of Dcir1^-/- neutrophils to CXCL1/KC appeared normal. Pervanadate treatment induced binding of DCIR1 and Src homology region 2 domain-containing phosphatase (SHP)-2, possibly leading to CXCL1/KC expression. These results suggest that DCIR1 is involved in exacerbation of endotoxemic hepatitis, providing a new therapeutic target for lethal hepatitis.

Transforming growth factor β-induced protein promotes severe vascular inflammatory responses

RATIONALE

Sepsis is a systemic inflammatory condition resulting from bacterial infections; it has a high mortality rate and limited therapeutic options. Despite extensive research into the mechanisms driving bacterial sepsis, the target molecules controlling vascular leakage are still largely unknown. Transforming growth factor β-induced protein (TGFBIp) is an extracellular matrix protein expressed in several cell types, which is known to interact with integrins.

OBJECTIVES

The aim of this study was to determine the roles of TGFBIp in vascular proinflammatory responses, and the mechanisms of action driving these responses.

METHODS

Circulating levels of TGFBIp were measured in patients admitted to the hospital with sepsis, severe sepsis, and septic shock and in cecal ligation and puncture (CLP)-induced septic mice. Effects of TGFBIp knockout on CLP-induced septic mortality and effects of TGFBIp on multiple vascular proinflammatory responses were determined.

MEASUREMENTS AND MAIN RESULTS

Circulating levels of TGFBIp were significantly elevated compared with healthy controls, and were strongly correlated with disease severity. High blood TGFBIp levels were also observed in CLP-induced septic mice. The absence of the TGFBIp gene in mice attenuated CLP-induced sepsis. TGFBIp enhanced vascular proinflammatory responses including vascular permeability, adhesion and migration of leukocytes, and disruption of adherence junctions through interacting with integrin αvβ5.

CONCLUSIONS

Collectively, our findings demonstrate that the TGFBIp-αvβ5 axis can elicit severe inflammatory responses, suggesting it to be a potential target for development of diagnostics and therapeutics for sepsis.

Septic shock

Septic shock, the most severe complication of sepsis, is a deadly disease. In recent years, exciting advances have been made in the understanding of its pathophysiology and treatment. Pathogens, via their microbial-associated molecular patterns, trigger sequential intracellular events in immune cells, epithelium, endothelium, and the neuroendocrine system. Proinflammatory mediators that contribute to eradication of invading microorganisms are produced, and anti-inflammatory mediators control this response. The inflammatory response leads to damage to host tissue, and the anti-inflammatory response causes leucocyte reprogramming and changes in immune status. The time-window for interventions is short, and treatment must promptly control the source of infection and restore haemodynamic homoeostasis. Further research is needed to establish which fluids and vasopressors are best. Some patients with septic shock might benefit from drugs such as corticosteroids or activated protein C. Other therapeutic strategies are under investigation, including those that target late proinflammatory mediators, endothelium, or the neuroendocrine system.

Delayed administration of human inter-alpha inhibitor proteins reduces mortality in sepsis

OBJECTIVE

We have recently shown that administration of human inter-alpha inhibitor proteins (IalphaIp) very early after the onset of sepsis maintains cardiovascular stability and reduced mortality. However, it remains unknown whether injection of IalphaIp at later time points of sepsis has any beneficial effects. We therefore hypothesized that IalphaIp and its active component bikunin are reduced in sepsis and that the delayed administration of IalphaIp also improves survival rate.

DESIGN

: Prospective, controlled, and randomized animal study.

SETTING

A research institute laboratory.

SUBJECTS

: Male adult Sprague-Dawley rats.

INTERVENTIONS

Rats were subjected either to polymicrobial sepsis by cecal ligation and puncture (CLP) or to sham operation followed by the administration of normal saline solution (i.e., fluid resuscitation).

MEASUREMENTS AND MAIN RESULTS

: Bikunin gene expression in the liver was measured by reverse transcription polymerase chain reaction. Plasma concentrations of IalphaIp were determined by Western blot at 5 and 20 hrs after CLP. IalphaIp clearance was assessed by injecting radioactive IalphaIp at 12 hrs post-CLP, and the half-life was determined. In addition, IalphaIp (30 mg/kg of body weight) or vehicle was administered at 1, 5, or 10 hrs (single treatment) or at both 10 and 20 hrs (double treatment) post-CLP. The necrotic cecum was excised at 20 hrs post-CLP, and 10-day survival was recorded. The results indicate that bikunin gene expression decreased significantly at 20 hrs post-CLP. Moreover, IalphaIp concentrations decreased significantly at 5 and 20 hrs post-CLP, and its half-life increased from 5.6 +/- 0.3 hrs to 11.8 +/- 2.7 hrs (p <.05), suggesting down-regulation of IalphaIp in sepsis despite the decreased clearance. Administration of IalphaIp at 1 hr post-CLP improved the survival rate from 50% to 92% (p <.05), whereas there was no significant improvement when IalphaIp was administrated at 5 or 10 hrs post-CLP. However, double injection of IalphaIp at 10 and 20 hrs post-CLP (i.e., severe sepsis) increased the survival rate from 44% to 81% (p <.05).

CONCLUSION

Since delayed but repeated administration of human IalphaIp improves survival after CLP, this compound appears to be a useful agent for the treatment of severe sepsis.

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.

Metalloproteinase inhibition reduces lung injury and improves survival after cecal ligation and puncture in rats

BACKGROUND

Neutrophil activation with concomitant matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) release has been implicated in the development of sepsis-induced acute lung injury. We hypothesized that COL-3, a chemically modified tetracycline known to inhibit MMP-2 and MMP-9, would reduce lung injury and improve survival in rats following cecal ligation and puncture (CLP).

METHODS

Sprague-Dawley rats were separated into five groups: 1) sham CLP+ carboxymethylcellulose (CMC; vehicle for COL-3, n = 6); 2) sham CLP + COL-3 (n = 6); 3) CLP + CMC (n = 10); 4) CLP + single-dose (SD) COL-3 administered concomitant with CLP (n = 9); and 5) CLP + multiple-dose (MD) COL-3 administered concomitant with CLP and at 24 h after CLP (n = 15). Rats were sacrificed at 168 h (7 days) or immediately after death, with survival defined as hours after CLP. Histological lung assessment was made based on neutrophil infiltration, alveolar wall thickening, and intraalveolar edema fluid. Lung MMP-2 and MMP-9 levels were assessed by immunohistochemistry. MMP-2 and MMP-9 levels were correlated with survival by simple regression analysis.

RESULTS

The mortality of rats in the cecal ligation and puncture without treatment group (CLP + CMC) was 70% at 168 h. A single dose of COL-3 in the CLP + COL-3 (SD) group significantly reduced mortality to 54%. Furthermore, with a repeat dose of COL-3 at 24 h after CLP, mortality was significantly reduced to 33%. Pathologic lung changes seen histologically in the CLP + CMC group were significantly reduced by COL-3. A significant reduction in lung tissue levels of MMP-2 and MMP-9 was noted in both groups treated with COL-3. Reduction of MMP-2 and MMP-9 levels correlated with improved survival.

CONCLUSION

Inhibition of MMP-2 and MMP-9 by COL-3 in a clinically relevant model of sepsis-induced acute lung injury reduces pulmonary injury and improves survival in a dose-dependent fashion. Our results suggest that prophylactic treatment with COL-3 in high-risk patients may reduce the morbidity and mortality associated with sepsis-induced acute respiratory distress syndrome.

Generation of C5a by phagocytic cells

The complement activation product, C5a, is a powerful phlogistic factor. Using antibodies to detect human or rat C5a, incubation at pH 7.4 of human blood neutrophils or rat alveolar macrophages (AMs) with C5 in the presence of phorbol 12-myristate 13-acetate (PMA) led to generation of C5a. Rat AMs activated with lipopolysaccharide also generated C5a from C5. With activated neutrophils, extensive cleavage of C5 occurred, whereas activated macrophages had much more selective proteolytic activity for C5. Peripheral blood human or rat mononuclear cells and rat alveolar epithelial cells when stimulated with phorbol ester all failed to demonstrate an ability to cleave C5, suggesting a specificity of C5 cleavage by phagocytic cells. With rat AMs, C5a generation was time-dependent and was blocked if AMs were pretreated with inhibitors of transcription or protein synthesis (actinomycin D or cycloheximide). Similar treatment of activated human polymorphonuclear leukocytes only partially reduced C5a generation after addition of C5. C5a generated by activated AMs was biologically (chemotactically) active. This generation was sensitive to serine protease inhibitors but not to other classes of inhibitors. These data indicate that phagocytic cells, especially lung macrophages, can generate C5a from C5. In the context of the lung, this may represent an important C5a-generating pathway that is independent of the plasma complement system.

Analysis of local and systemic inflammatory responses induced by polymicrobial peritonitis in mice

BACKGROUND

Abdominal sepsis induces a local production of proinflammatory mediators that may trigger both septic shock and organ-system dysfunction.

AIMS

The present study analyzed exudation, cell migration, and CD11a and CD18 subset cells of both local and systemic responses induced by fecal peritonitis in mice.

METHODS

Animals were anesthetized and, after performing a midline incision in the abdomen, the cecum was ligated and punctured twice with a needle. Sham-operated animals were included. Some groups were previously treated with Evans blue dye (intravenously) to further evaluate the amount of tissue and abdominal cavity leakages.

RESULTS

Fecal peritonitis triggered a local inflammatory reaction with an increased number of leukocytes and exudation between 6 and 48 h (p < 0.01). Although CD11a/CD18-positive cells in the abdomen peaked after 24h, a significant decrease of them was detected after 48 h (p < 0.05). At the studied period of time (6-48 h), different degrees of exudation in several organs occurred, whereas a significant late recruitment (24 h) of CD11a/CD18 cells into the lungs was observed.

CONCLUSIONS

In this model, cell migration and exudation at the site of injury occurred in parallel. However, in the lungs, the recruitment of leukocytes that express CD11a/CD18 adhesion molecules constitutes a non-dependent event in relation to fluid leakage accumulation at this site.

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

BACKGROUND

Activated neutrophils are reported to be closely involved in ischemia-reperfusion injury after lung transplantation. We investigated the beneficial effects of a new recombinant specific neutrophil elastase inhibitor, ONO-5046.Na, and an extracorporeal-type granulotrap (G-1) column on ischemia-reperfusion lung injury, by using an in situ warm lung ischemia model in dogs.

METHODS

Warm ischemia was induced for 3 hours by clamping the pulmonary arteries and veins. The left main bronchus was bisected and reanastomosed prior to reperfusion. The left lung was collapsed for 3 hours. A total of 27 adult mongrel dogs were divided into three groups: the control group (n = 9) treated with a saline vehicle; the ONO group (n = 9), in which ONO-5046.Na was continuously administrated from before induced ischemia and to ending 2 hours after reperfusion; and the G-1 group (n = 9), in which a G-1 column was applied for 90 minutes starting 30 minutes before reperfusion under passive bypass support.

RESULTS

Circulating neutrophils in the G-1 group decreased significantly (p<.05) compared to preischemia, and significantly decreased compared with the other groups after reperfusion. Oxygenation was improved actually and pulmonary vascular resistance was kept lower level after the administration of ONO-5046.Na. The increase of lung weight was significantly ameliorated in both the G-1 and ONO groups. In the histopathological study, lungs from the control group demonstrated diffuse alveolar edema, neutrophil infiltration, massive alveolar exudate and hemorrhage, and thickening of the interstitium. Lungs from the G-1 group showed mild swelling of the alveolar wall and neutrophil infiltration. Lungs from the ONO group showed virtually no abnormalities.

CONCLUSION

This study demonstrated that a neutrophil elastase inhibitor and neutrophil depletion prevented lung reperfusion injury. These treatments may prevent ischemia and reperfusion injury in lung transplantation.

Continuous antibiotic treatment for experimental abdominal sepsis: effects on organ inflammatory cytokine expression and neutrophil sequestration

BACKGROUND

Tumour necrosis factor (TNF) alpha and interleukin (IL) 1 beta are produced in the lung after peritonitis and may contribute to neutrophil-mediated organ injury. It was hypothesized that, during experimental peritonitis, continuous rather than intermittent antibiotic therapy would reduce lung expression of TNF-alpha and IL-1 beta messenger RNA (mRNA) and neutrophil sequestration.

METHODS

After caecal ligation and puncture, mice received either intermittent or continuous cefoxitin, or continuous metronidazole or aztreonam. Cytokine mRNAs were determined by reverse transcription differential polymerase chain reaction and lung neutrophil content by myeloperoxidase (MPO) assay.

RESULTS

Continuous cefoxitin reduced median (interquartile range (i.q.r.)) lung IL-1 beta mRNA expression ((ratio to beta-actin): continuous 0.18 (0.14-0.34), intermittent 0.46 (0.44-0.49), saline 0.43 (0.38-0.53), P < 0.05) and median (i.q.r.) lung MPO content (continuous 22.5 (9.7-40), intermittent 65 (57.5-76), saline 47 (41-64), P < 0.05) compared with intermittent therapy and saline controls. Continuous infusion was also associated with reduced bacteraemia (P < 0.05) but not serum TNF-alpha or endotoxin levels. Both continuous metronidazole and aztreonam reduced lung MPO concentration (P < 0.05) and TNF-alpha and IL-1 beta mRNA expression (P < 0.05) compared with those in saline controls. These effects were dependent on a reduction in the number of susceptible bacteria rather than serum TNF-alpha or endotoxin levels.

CONCLUSION

The stimulus for organ inflammatory cytokine production and neutrophil sequestration during peritonitis is the level of bacteraemia present, which is more effectively controlled with continuous antibiotic therapy.

Enhanced endothelial cell injury by activated neutrophils in patients with obstructive jaundice

BACKGROUND/AIMS

A high incidence of complications has been documented in patients with obstructive jaundice after operations. Recent reports have revealed that neutrophils are involved in the mechanism causing postoperative complications. However, there are few reports investigating the interaction between neutrophils and endothelial cells in obstructive jaundice. The aim of this study was to evaluate neutrophil-mediated endothelial cell injury in patients with obstructive jaundice.

METHODS

Patients were divided into three groups: those with normal liver, obstructive jaundice, and relief of obstructive jaundice. Neutrophils were isolated from patients individually. Human umbilical vein endothelial cells and neutrophils were co-cultured after addition of phorbol myristate acetate. The release of lactate dehydrogenase and thrombomodulin was measured in the medium.

RESULTS

Lactate dehydrogenase and thrombomodulin were released in the co-culture medium, and Eglin C, which is an elastase inhibitor, reduced the release of lactate dehydrogenase and thrombomodulin in a dose-dependent manner. The release of lactate dehydrogenase and thrombomodulin in the group with relief of obstructive jaundice was significantly higher than in the group with normal liver. There was no significant difference between the group with obstructive jaundice and the group with normal liver. The elastase activity in neutrophil suspension was similarly higher in the group with relief of obstructive jaundice than in the group with normal liver.

CONCLUSIONS

This study suggests that neutrophils in patients with obstructive jaundice are not activated before its relief. After relief of obstructive jaundice, neutrophils are strongly primed and have the potential to cause endothelial cell injury. The neutrophil "priming" in patients with obstructive jaundice may be associated with the frequent occurrence of postoperative complications.

The pulmonary inflammatory response to experimental fecal peritonitis: relative roles of tumor necrosis factor-alpha and endotoxin

The roles of endotoxin (LPS) and tumor necrosis factor-alpha (TNF-alpha) in the causation of organ injury during sepsis are unclear. To study LPS and TNF-alpha in the genesis of lung inflammation after cecal ligation and puncture (CLP), we used endotoxin-resistant (C3H/HeJ) and endotoxin-sensitive mice (C3H/HeOuJ). We examined lung neutrophil sequestration, interleukin 1 (IL-1)beta mRNA expression, IL-1 beta protein expression, and injury. We also determined the expression of two C-X-C chemokine mRNAs, macrophage inflammatory protein-2 (MIP-2) and KC, in the lung to determine whether in vivo, endotoxin, or TNF-alpha are significant modulators of MIP-2 and KC mRNA expression. After CLP, increased neutrophils sequestrated in the lungs of both strains of mice and coincided with an increase in expression of IL-1 beta, MIP-2 and KC mRNAs, and IL-1 beta protein. Lung and serum TNF-alpha were significantly increased in the C3H/HeOuJ strain but not in the C3H/HeJ strain. Histologic studies of the lung revealed similar injury in both strains. Our results suggest that bacterial factors other than endotoxin cause lung neutrophil sequestration and injury after CLP and, further, that TNF-alpha production is not a prerequisite. Our findings also suggest a potential role for local pulmonary chemokine production in the control of neutrophil sequestration after CLP.