Thrombin and factor Xa enhance neutrophil chemoattractant production after ischemia/reperfusion in the rat liver

Xa inhibitor edoxaban ameliorates hepatic ischemia-reperfusion injury via PAR-2-ERK 1/2 pathway

Hepatic ischemia-reperfusion injury causes liver damage during surgery. In hepatic ischemia-reperfusion injury, the blood coagulation cascade is activated, causing microcirculatory incompetence and cellular injury. Coagulation factor Xa (FXa)- protease-activated receptor (PAR)-2 signaling activates inflammatory reactions and the cytoprotective effect of FXa inhibitor in several organs. However, no studies have elucidated the significance of FXa inhibition on hepatic ischemia-reperfusion injury. The present study elucidated the treatment effect of an FXa inhibitor, edoxaban, on hepatic ischemia-reperfusion injury, focusing on FXa-PAR-2 signaling. A 60 min hepatic partial-warm ischemia-reperfusion injury mouse model and a hypoxia-reoxygenation model of hepatic sinusoidal endothelial cells were used. Ischemia-reperfusion injury mice and hepatic sinusoidal endothelial cells were treated and pretreated, respectively with or without edoxaban. They were incubated during hypoxia/reoxygenation in vitro. Cell signaling was evaluated using the PAR-2 knockdown model. In ischemia-reperfusion injury mice, edoxaban treatment significantly attenuated fibrin deposition in the sinusoids and liver histological damage and resulted in both anti-inflammatory and antiapoptotic effects. Hepatic ischemia-reperfusion injury upregulated PAR-2 generation and enhanced extracellular signal-regulated kinase 1/2 (ERK 1/2) activation; however, edoxaban treatment reduced PAR-2 generation and suppressed ERK 1/2 activation in vivo. In the hypoxia/reoxygenation model of sinusoidal endothelial cells, hypoxia/reoxygenation stress increased FXa generation and induced cytotoxic effects. Edoxaban protected sinusoidal endothelial cells from hypoxia/reoxygenation stress and reduced ERK 1/2 activation. PAR-2 knockdown in the sinusoidal endothelial cells ameliorated hypoxia/reoxygenation stress-induced cytotoxicity and suppressed ERK 1/2 phosphorylation. Thus, edoxaban ameliorated hepatic ischemia-reperfusion injury in mice by protecting against micro-thrombosis in sinusoids and suppressing FXa-PAR-2-induced inflammation in the sinusoidal endothelial cells.

NETosis in ischemic/reperfusion injuries: An organ-based review

Neutrophil extracellular trap (NETosis), the web-like structures induced by neutrophil death, is an important inflammatory mechanism of the immune system leading to reactive oxygen species production/coagulopathy, endothelial dysfunction, atherosclerosis, and ischemia. NETosis exerts its role through different mechanisms such as triggering Toll-like receptors, inflammatory cytokines, platelet aggregation, neutrophil activation/infiltration, and vascular impairment. NETosis plays a key role in the prognosis of coronary artery disease, ischemic injury of kidney, lung, gastrointestinal tract and skeletal muscles. In this review, we explored the molecular mechanisms involved in NETosis, and ischemic/reperfusion injuries in body organs.

Neutrophil-Induced Liver Injury and Interactions Between Neutrophils and Liver Sinusoidal Endothelial Cells

Neutrophils are the most abundant type of leukocytes with diverse functions in immune defense including production of reactive oxygen species, bacteriocidal proteins, neutrophil extracellular traps, and pro-inflammatory mediators. However, aberrant accumulation of neutrophils in host tissues and excessive release of bacteriocidal compounds can lead to unexpected injury to host organs. Neutrophil-mediated liver injury has been reported in various types of liver diseases including liver ischemia/reperfusion injury, nonalcoholic fatty liver disease, endotoxin-induced liver injury, alcoholic liver disease, and drug-induced liver injury. Yet the mechanisms of neutrophil-induced hepatotoxicity in different liver diseases are complicated. Current knowledge of these mechanisms are summarized in this review. In addition, a substantial body of evidence has emerged showing that liver sinusoidal endothelial cells (LSECs) participate in several key steps of neutrophil-mediated liver injury including neutrophil recruitment, adhesion, transmigration, and activation. This review also highlights the current understanding of the interactions between LSECs and neutrophils in liver injury. The future challenge is to explore new targets for selectively interfering neutrophil-induced liver injury without impairing host defense function against microbial infection. Further understanding the role of LSECs in neutrophil-induced hepatotoxicity would aid in developing more selective therapeutic approaches for liver disease.

The Impact of Dabigatran Treatment on Sinusoidal Protection Against Hepatic Ischemia/Reperfusion Injury in Mice

Thrombin is a key player in the coagulation cascade, and it is attracting much attention as a promotor of cellular injured signaling. In ischemia/reperfusion injury (IRI), which is a severe complication of liver transplantation, thrombin may also promote tissue damage. The aim of this study is to reveal whether dabigatran, a direct thrombin inhibitor, can attenuate hepatic IRI with focusing on a protection of sinusoidal endothelial cells (SECs). Both clinical patients who underwent hepatectomy and in vivo mice model of 60-minute hepatic partial-warm IRII, thrombin generation was evaluated before and after IRI. In next study, IRI mice were treated with or without dabigatran. In addition, hepatic SECs and hepatocytes pretreated with or without dabigatran were incubated in hypoxia/reoxygenation (H-R) environment in vitro. Thrombin generation evaluated by thrombin-antithrombin complex (TAT) was significantly enhanced after IRI in the clinical study and in vivo study. Thrombin exacerbated lactate dehydrogenase cytotoxicity levels in a dose-dependent manner in vitro. In an IRI model of mice, dabigatran treatment significantly improved liver histological damage, induced sinusoidal protection, and provided both antiapoptotic and anti-inflammatory effects. Furthermore, dabigatran not only enhanced endogenous thrombomodulin (TM) but also reduced excessive serum high-mobility group box-1 (HMGB-1). In H-R models of SECs, not hepatocytes, pretreatment with dabigatran markedly attenuated H-R damage, enhanced TM expression in cell lysate, and decreased extracellular HMGB-1. The supernatant of SECs pretreated with dabigatran protected hepatocytes from H-R damage and cellular death. Thrombin exacerbated hepatic IRI, and excessive extracellular HMGB-1 caused severe inflammation-induced and apoptosis-induced liver damage. In this situation, dabigatran treatment improved vascular integrity via sinusoidal protection and degraded HMGB-1 by endogenous TM enhancement on SECs, greatly ameliorating hepatic IRI.

The coagulation factor Xa/protease activated receptor-2 axis in the progression of liver fibrosis: a multifaceted paradigm

Hepatic fibrosis is a common response to virtually all forms of chronic liver injury independent of the etiologic agent. Despite the relatively large population of patients suffering from hepatic fibrosis and cirrhosis, no efficient and well-tolerated drugs are available for the treatment of this disorder. The lack of efficient treatment options is at least partly because the underlying cellular mechanisms leading to hepatic fibrosis are only partly understood. It is thus of pivotal importance to better understand the cellular processes contributing to the progression of hepatic fibrosis. Interestingly in this perspective, a common feature of fibrotic disease of various organs is the activation of the coagulation cascade and hepatic fibrosis is also accompanied by a local hypercoagulable state. Activated blood coagulation factors directly target liver cells by activating protease-activated receptors (PAR) thereby inducing a plethora of cellular responses like (among others) proliferation, migration and extracellular matrix production. Coagulation factor driven PAR activation thus establishes a potential link between activation of the coagulation cascade and the progression of fibrosis. The current review focuses on blood coagulation factor Xa and summarizes the variety of cellular functions induced by factor Xa-driven PAR-2 activation and the subsequent consequences for tissue repair and hepatic fibrosis.

Effects of Custodiol-N, a novel organ preservation solution, on ischemia/reperfusion injury

OBJECTIVE

Custodiol (histidine-tryptophan-ketoglutarate solution) is a leading organ preservation solution. On the basis of this solution, the novel Custodiol-N was developed. The present study investigated the effects of Custodiol-N in a rat model of heart transplantation.

METHODS

Heterotopic heart transplantation was performed in Lewis rats. Four groups were assigned: 2 Custodiol-N-treated groups and 2 Custodiol-treated control groups with a reperfusion time of 1 hour and 24 hours, respectively. Coronary blood flow, left ventricular pressure, its first derivative, left ventricular end-diastolic pressure, endothelium-dependent vasodilatation to bradykinin and endothelium-independent vasodilatation to sodium nitroprusside, and adenosine triphosphate content were measured. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining was performed to detect apoptotic cardiomyocytes.

RESULTS

After 1 hour, coronary blood flow (3.99 +/- 0.24 mL/min/g vs 2.86 +/- 0.35 mL/min/g; P < .05), left ventricular pressure (117 +/- 18 mm Hg vs 82 +/- 4 mm Hg; P < .05), and first derivative of left ventricular pressure (3453 +/- 577 mm Hg/s vs 1740 +/- 116 mm Hg/s; P < .05) were significantly higher in the Custodiol-N group compared with the corresponding control. The left ventricular systolic pressure-volume relationship was significantly steeper, indicating improved contractility. Vasodilatatory response to sodium nitroprusside did not show any major differences between the groups. Response to bradykinin resulted in a significantly higher increase in coronary blood flow in the Custodiol-N group (92% +/- 4% vs 60% +/- 5%; P < .05). Myocardial adenosine triphosphate content was significantly higher in the Custodiol-N group (9.84 +/- 0.68 mumol/g vs 1.86 +/- 0.41 mumol/g; P < .05). Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining showed a significantly reduced apoptosis level (21.58% +/- 1.59% vs 27.23% +/- 1.54%; P < .05) in the Custodiol-N group.

CONCLUSION

Custodiol-N improves myocardial and endothelial function during the critical phase of reperfusion after heart transplantation.

Role of the thrombin/protease-activated receptor 1 pathway in intestinal ischemia-reperfusion injury in rats

CXC chemokines, including human interleukin-8 and rat cytokine-induced neutrophil chemoattractant-1, play a crucial role in the pathogenesis of intestinal inflammation induced by ischemia-reperfusion (I-R). Thrombin and its specific receptor, protease-activated receptor 1 (PAR1), act as important players in inflammation. However, the association between thrombin activation and chemokine production during I-R has not been well studied. We investigated whether thrombin and PAR1 might be involved in the pathophysiology of intestinal I-R, using an in vivo model. Intestinal damage was induced by clamping the superior mesenteric artery for 30 min followed by reperfusion in male Wistar rats. Thrombin-antithrombin complex was measured as an indicator of thrombin activation. PAR1 expression in the intestine was evaluated by real-time PCR. The severity of the intestinal mucosal injury was evaluated on the distal segment of the ileum by several biochemical markers and histological findings. Reperfusion significantly increased the serum levels of thrombin-antithrombin complex and enhanced PAR1 expression in the intestinal mucosa. The levels of both intraluminal hemoglobin and protein were significantly increased in the I-R group. The mucosal myeloperoxidase activity and expressions and/or productions of cytokine-induced neutrophil chemoattractant-1 and TNF-alpha were significantly increased after I-R. These increases were inhibited by the treatment of rat with antithrombin intravenously before I-R at a dose of 30 U/kg. These results suggest that the thrombin/PAR1 pathway plays an important role in the production of these cytokines during I-R and that antithrombin exerts potent anti-inflammatory effects on this injury via inhibition of proinflammatory cytokines.

Coagulation-dependent gene expression and liver injury in rats given lipopolysaccharide with ranitidine but not with famotidine

In an animal model of drug idiosyncrasy, rats cotreated with nonhepatotoxic doses of lipopolysaccharide (LPS) and ranitidine (RAN) develop hepatocellular injury, whereas rats treated with LPS and famotidine (FAM) do not. The coagulation system and neutrophils (PMNs) are requisite mediators of LPS/RAN-induced liver injury. We tested the hypothesis that unique gene expression in LPS/RAN-treated rats requires coagulation system activation and that these changes are absent in rats given LPS and FAM. Rats were treated with a nonhepatotoxic dose of LPS (44.4 x 10(6) endotoxin units/kg i.v.) or its vehicle, and then 1 h later, they were treated with heparin (3000 U/kg) or its vehicle. One hour thereafter, they were given RAN (30 mg/kg), FAM (6 mg/kg, a pharmacologically equiefficacious dose, or 28.8 mg/kg, an equimolar dose), or vehicle (i.v.). They were killed 2 or 6 h after drug treatment for evaluation of hepatotoxicity, coagulation system activation, and liver gene expression (2 h only). Statistical filtering of gene array results and real-time polymerase chain reaction identified groups of genes expressed in LPS/RAN-treated rats but not LPS/FAM-treated rats that were either changed or unchanged by heparin administration. For example, LPS/RAN-induced mRNA expression of the inflammatory mediators interleukin-6, cyclooxygenase-2, and macrophage inflammatory protein-2 (MIP-2) was reduced by anticoagulation. Enhancement of serum MIP-2 and plasminogen activator inhibitor-1 concentrations in LPS/RAN-treated rats was prevented by anticoagulation. The results suggest cross-talk between hemostasis-induced gene expression and inflammation (e.g., PMN function) in the genesis of hepatocellular injury in LPS/RAN-treated rats. In contrast, neither the expression of such genes nor hepatocellular necrosis occurred in rats treated with LPS/FAM.

Effects of anticoagulant treatment on intestinal ischaemia and reperfusion injury in rats

BACKGROUND

In recent years it has become increasingly clear that a cross-talk between the inflammatory response and blood coagulation exists, although many of the underlying mechanisms remain unclear. In the present study we investigated the potential anti-inflammatory properties of two different anticoagulant compounds, i.e. active-site inactivated FVIIa (FVIIai) and fondaparinux sodium, a selective FXa inhibitor, administered as pretreatment in a model of intestinal I/R in rats.

METHODS

Endothelial barrier permeability was assessed using the vascular leakage of radiolabelled human serum albumin, tissue neutrophil sequestration was quantitated by myeloperoxidase (MPO) activity, and plasma levels of macrophage inflammatory protein (MIP)-2 were examined using an enzyme-linked-immuno-sorbent assay after 40 min of intestinal ischaemia and 6 h of reperfusion in the rat (n = 34). Pretreatment with FVIIai or fondaparinux sodium was administered 90 min before initiation of ischaemia.

RESULTS

Endothelial-barrier permeability in all examined organs, myeloperoxidase activity in the lungs, and ileum and MIP-2 levels in plasma increased after intestinal I/R. Pretreatment with FVIIai decreased the endothelial barrier permeability and MPO activity in the ileum, and a tendency towards decreased permeability was also observed in the lungs. Fondaparinux did not affect the endothelial barrier permeability or MPO activity. Both FVIIai and fondaparinux decreased the MIP-2 levels in plasma after intestinal I/R.

CONCLUSIONS

Inhibition of the TF-FVIIa complex by FVIIai can attenuate inflammatory responses in connection with intestinal I/R-injury and could represent a potentially important therapeutic strategy for the prevention of organ dysfunction. Potential anti-inflammatory properties of fondaparinux and other inhibitors of FXa are not excluded and need further investigation.

Importance of platelets and fibrinogen in neutrophil-endothelial cell interactions in septic shock

OBJECTIVE

To examine the role of platelets, fibrin, and adhesion molecules in mediating neutrophil-endothelial cell interactions in septic shock.

DESIGN

Controlled experiments using phase contrast microscopy to examine neutrophil, platelet, and endothelial cell interactions in flowing cell suspensions under simulated physiologic conditions.

SETTING

University research laboratory.

PATIENTS

Adult patients with septic shock and normal volunteers.

INTERVENTIONS

Microslides were coated with human umbilical vein endothelial cells. Neutrophils were removed from control subjects and patients in septic shock and were perfused over endothelial cells at rates representing a range of physiologic shear stresses. In an attempt to examine the effects of fibrin deposition on neutrophil-endothelial cell interactions, neutrophils, with and without platelets, were suspended in plasma and serum was removed from patients in septic shock. In addition, blocking monoclonal antibodies against the platelet receptor P-selectin and neutrophil receptor CD11b/CD18, and a platelet glycoprotein IIb/IIIa inhibitor, were incubated with cells suspended in plasma. Phase contrast video microscopy was used to count the number of neutrophils/mm adherent to endothelial cells during cessation of flow. Neutrophil rolling velocity was calculated as the time required for neutrophils to move across a 1-mm field (mm/sec). Leukoaggregation was defined as the number of neutrophils in aggregates (three or more nuclei) across a 1-mm field.

MEASUREMENTS AND MAIN RESULTS

Normal neutrophils exposed to plasma from patients with septic shock demonstrated significant increases in aggregation and endothelial cell adherence with associated decreases in neutrophil rolling velocity. These changes were significantly enhanced in the presence of platelets and significantly attenuated in the presence of serum, which is fibrinogen depleted. Preincubation with antibodies to the surface receptors P-selectin, CD11b/CD18, and glycoprotein IIb/IIIa abrogated the changes in neutrophil aggregation, adhesion, and rolling velocity.

CONCLUSIONS

These data suggest that platelets and fibrinogen play an important role in mediating neutrophil-endothelial cell adherence in septic shock.

Coagulative disorders in human acute pancreatitis: role for the D-dimer

INTRODUCTION AND AIMS

We investigated coagulative disorders, particularly the role of the D-dimer, in acute pancreatitis where coagulation abnormalities related to disease severity are known to occur.

METHODOLOGY

D-dimer levels in 30 patients with acute pancreatitis were evaluated; pancreatitis was mild and uncomplicated in 11 patients, accompanied by complications in 15, and severe in 4. We attempted to find a relationship between the D-dimer level and the antithrombin III level, prothrombin time, partial thromboplastin time, the C-reactive protein level, and results of routine laboratory tests.

RESULTS

In the 11 patients with uncomplicated pancreatitis, the D-dimer level increased about 1.5 times over the limit, while in the 15 patients with complications and the four patients with severe pancreatitis, the D-dimer level increased about seven times above the normal limit; this difference was highly significant (p < 0.0001). The rise in the D-dimer level was inversely related to albumin and calcium levels (p = 0.0001) and directly related to the C-reactive protein level, fibrinogen level and leukocyte count (p = 0.0001), prothrombin time (p = 0.006), partial thromboplastin time (p = 0.03), and acute abdominal collections and lung involvement (p = 0.0001). The increase appeared early on, lasting for the entire study and peaking on days 3-6.

CONCLUSIONS

The D-dimer is the expression of pancreatitis and the extension of systemic involvement; it may be considered a prominent link in the chain of events leading to severe disease.