Expression of tissue factor in hepatic ischemic-reperfusion injury of the rat

The Tissue Factor Pathway in Cancer: Overview and Role of Heparan Sulfate Proteoglycans

Historically, the only focus on tissue factor (TF) in clinical pathophysiology has been on its function as the initiation of the extrinsic coagulation cascade. This obsolete vessel-wall TF dogma is now being challenged by the findings that TF circulates throughout the body as a soluble form, a cell-associated protein, and a binding microparticle. Furthermore, it has been observed that TF is expressed by various cell types, including T-lymphocytes and platelets, and that certain pathological situations, such as chronic and acute inflammatory states, and cancer, may increase its expression and activity. Transmembrane G protein-coupled protease-activated receptors can be proteolytically cleaved by the TF:FVIIa complex that develops when TF binds to Factor VII (PARs). The TF:FVIIa complex can activate integrins, receptor tyrosine kinases (RTKs), and PARs in addition to PARs. Cancer cells use these signaling pathways to promote cell division, angiogenesis, metastasis, and the maintenance of cancer stem-like cells. Proteoglycans play a crucial role in the biochemical and mechanical properties of the cellular extracellular matrix, where they control cellular behavior via interacting with transmembrane receptors. For TFPI.fXa complexes, heparan sulfate proteoglycans (HSPGs) may serve as the primary receptor for uptake and degradation. The regulation of TF expression, TF signaling mechanisms, their pathogenic effects, and their therapeutic targeting in cancer are all covered in detail here.

The impact of short-term machine perfusion on the risk of cancer recurrence after rat liver transplantation with donors after circulatory death

Hypothermic and normothermic ex vivo liver perfusions promote organ recovery after donation after circulatory death (DCD). We tested whether these perfusions can reduce the risk of hepatocellular carcinoma (HCC) recurrence in a 1h-DCD syngeneic transplantation model, using Fischer F344 rats. DCD grafts were machine perfused for 2h with hypothermic perfusion (HOPE) or normothermic perfusion (NORMO), and transplanted. After reperfusion, we injected HCC cells into the vena porta. On day 28 after transplantation, we assessed tumour volumes by MRI. Control rats included transplantations with Fresh and non-perfused DCD livers. We observed apoptotic-necrotic hepatocyte foci in all DCD grafts, which were more visible than in the Fresh liver grafts. Normothermic perfusion allowed a faster post-transplant recovery, with lower day 1 levels of transaminases compared with the other DCD. Overall, survival was similar in all four groups and all animals developed HCCs. Total tumor volume was lower in the Fresh liver recipients compared to the DCD and DCD+HOPE recipients. Volumes in DCD+NORMO recipients were not significantly different from those in the Fresh group. This experiment confirms that ischemia/reperfusion injury promotes HCC cell engraftment/growth after DCD liver transplantation. Using the present extreme 1h ischemia model, both hypothermic and normothermic perfusions were not effective in reducing this risk.

Role of the plasma cascade systems in ischemia/reperfusion injury of bone

Ischemia/reperfusion (I/R) injury has been extensively studied in organs such as heart, brain, liver, kidney, and lung. As a vascularized organ, bone is known to be susceptible to I/R injury too, but the respective mechanisms are not well understood to date. We therefore hypothesized that, similar to other organs, plasma cascade-induced inflammation also plays a role in bone I/R injury. Reperfusion injury in rat tibia was induced by unilateral clamping of the femoral artery and additional use of a tourniquet, while keeping the femoral vein patent to prevent venous congestion. Rats were subjected to 4h ischemia and 24h reperfusion. Deposition of complement fragment C3b/c and fibrin as well as expression of tissue factor (TF), tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), and E-selectin was detected by immunohistochemistry. In plasma, the levels of high mobility group box1 (HMGB1) were measured by ELISA. The total level of complement in serum was assessed by the CH50 test. Our results show that deposition of C3b/c was significantly increased with respect to healthy controls in cortical bone as well as in marrow of reperfused limbs. C3b/c deposition was also increased in cortical bone, but not in bone marrow, of contralateral limbs. Deposition of fibrin, as well as expression of PAI-1, was significantly increased in bone after ischemia and reperfusion, whereas expression of tPA was reduced. These differences were most prominent in vessels of bone, both in marrow and cortical bone, and both in reperfused and contralateral limbs. However, PAI-1, was only increased in vessels of reperfused cortical bone and there were no significant changes in expression of E-selectin. With respect to solid bone tissue, a significant increase of C3b/c and fibrin deposition was shown in osteocytes, and for fibrin also in the bone matrix, in both contralateral and reperfused cortical bone compared with normal healthy controls. A slight expression of TF was visible in osteocytes of the normal healthy control group, while TF was not present in the experimental groups. Moreover, CH50 values in serum decreased over time and HMGB1 was significantly increased in plasma of animals at the end of reperfusion. We conclude that ischemia and reperfusion of bone leads to activation of the complement and coagulation systems and a downregulation of the fibrinolytic cascade. In the acute phase, a vascular inflammation induced by activation of the plasma cascade systems also occurs in the bone. This is similar to I/R injury of other vascularized organs and tissues.

The effects of tacrolimus on the activity and expression of tissue factor in the rat ovary with ischemia-reperfusion induced injury

In the present study, the effects of tacrolimus on the activity and expression of tissue factor (TF) were investigated in the ovarian ischemia-reperfusion induced injury in rats. Twenty-eight female rats (8-12 weeks, 300-350 g) were divided into four groups: control, ischemia-reperfusion (IR), tacrolimus treated before ischemia (TBI), and tacrolimus treated before reperfusion (TBR) groups (n=7/per group). TF activity was measured using Quick's method, whereas TF expression was examined immunohistochemically. TF activity was significantly higher in all treated groups compared with the control group. Strong ovarian TF expression was demonstrated in the IR and TBR groups. Moreover, tacrolimus decreased TF activity in the TBI group compared with the IR group. The decreased activity of TF in the ovarian IR model may prevent IR-related inflammation during transplant procedure.

Protease-activated receptor 1 and hematopoietic cell tissue factor are required for hepatic steatosis in mice fed a Western diet

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of obesity and metabolic syndrome and contributes to increased risk of cardiovascular disease and liver-related morbidity and mortality. Indeed, obese patients with metabolic syndrome generate greater amounts of thrombin, an indication of coagulation cascade activation. However, the role of the coagulation cascade in Western diet-induced NAFLD has not been investigated. Using an established mouse model of Western diet-induced NAFLD, we tested whether the thrombin receptor protease-activated receptor 1 (PAR-1) and hematopoietic cell-derived tissue factor (TF) contribute to hepatic steatosis. In association with hepatic steatosis, plasma thrombin-antithrombin levels and hepatic fibrin deposition increased significantly in C57Bl/6J mice fed a Western diet for 3 months. PAR-1 deficiency reduced hepatic inflammation, particularly monocyte chemoattractant protein-1 expression and macrophage accumulation. In addition, PAR-1 deficiency was associated with reduced steatosis in mice fed a Western diet, including reduced liver triglyceride accumulation and CD36 expression. Similar to PAR-1 deficiency, hematopoietic cell TF deficiency was associated with reduced inflammation and reduced steatosis in livers of low-density lipoprotein receptor-deficient mice fed a Western diet. Moreover, hematopoietic cell TF deficiency reduced hepatic fibrin deposition. These studies indicate that PAR-1 and hematopoietic cell TF are required for liver inflammation and steatosis in mice fed a Western diet.

Binding of anti-GRP78 autoantibodies to cell surface GRP78 increases tissue factor procoagulant activity via the release of calcium from endoplasmic reticulum stores

The increased risk of venous thromboembolism in cancer patients has been attributed to enhanced tissue factor (TF) procoagulant activity (PCA) on the surface of cancer cells. Recent studies have shown that TF PCA can be modulated by GRP78, an endoplasmic reticulum (ER)-resident molecular chaperone. In this study, we investigated the role of cell surface GRP78 in modulating TF PCA in several human cancer cell lines. Although both GRP78 and TF are present on the cell surface of cancer cells, there was no evidence of a stable interaction between recombinant human GRP78 and TF, nor was there any effect of exogenously added recombinant GRP78 on cell surface TF PCA. Treatment of cells with the ER stress-inducing agent thapsigargin, an inhibitor of the sarco(endo)plasmic reticulum Ca(2+) pump that causes Ca(2+) efflux from ER stores, increased cytosolic [Ca(2+)] and induced TF PCA. Consistent with these findings, anti-GRP78 autoantibodies that were isolated from the serum of patients with prostate cancer and bind to a specific N-terminal epitope (Leu(98)-Leu(115)) on cell surface GRP78, caused a dose-dependent increase in cytosolic [Ca(2+)] and enhanced TF PCA. The ability to interfere with cell surface GRP78 binding, block phospholipase C activity, sequester ER Ca(2+), or prevent plasma membrane phosphatidylserine exposure resulted in a significant decrease in the TF PCA induced by anti-GRP78 autoantibodies. Taken together, these findings provide evidence that engagement of the anti-GRP78 autoantibodies with cell surface GRP78 increases TF PCA through a mechanism that involves the release of Ca(2+) from ER stores. Furthermore, blocking GRP78 signaling on the surface of cancer cells attenuates TF PCA and has the potential to reduce the risk of cancer-related venous thromboembolism.

Cholestasis enhances liver ischemia/reperfusion-induced coagulation activation in rats

AIM

Cholestasis is associated with increased morbidity and mortality in patients undergoing major liver surgery. An additional risk is induced when vascular inflow occlusion is applied giving rise to liver ischemia/reperfusion (I/R) injury. The role of the coagulation system in this type of injury is elusive. The aim of the current study was to assess activation of coagulation following hepatic I/R injury in cholestatic rats.

METHODS

Male Wistar rats were randomized into two groups and subjected to bile duct ligation (BDL) or sham laparotomy. After 7 days, both groups underwent 30 min partial liver ischemia. Animals were sacrificed before ischemia or after 6 h, 24 h, and 48 h reperfusion.

RESULTS

Plasma AST and ALT levels were higher after I/R in cholestatic rats (P < 0.05). Hepatic necrosis, liver wet/dry ratio and neutrophil influx were increased in the BDL group up to 48 h reperfusion (P < 0.05). Liver synthetic function was decreased in the BDL group as reflected by prolonged prothrombin time after 6 h and 24 h reperfusion (P < 0.05). I/R in cholestatic rats resulted in a 12-fold vs. 7-fold (P < 0.01) increase in markers for thrombin generation and a 6-fold vs. 2-fold (P < 0.01) increase in fibrin degradation products (BDL vs. control, respectively). In addition, the cholestatic rats exhibited significantly decreased levels of antithrombin (AT) III and increased levels of the fibrinolytic inhibitor plasminogen activator inhibitor (PAI-1) during reperfusion.

CONCLUSIONS

Cholestasis significantly enhances I/R-induced hepatic damage and inflammation that concurs with an increased activation of coagulation and fibrinolysis.

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 propofol and etomidate on hydrogen peroxide-induced oxidative damage in hepatocyte

BACKGROUND

The present investigation was undertaken to evaluate the protective effect of propofol and etomidate against hydrogen peroxide (H2O2) induced oxidative damage in human hepatic SNU761 cells by measuring lactate dehydrogenase (LDH).

METHODS

The cell line of human hepatocellular carcinoma was grown for 24 hours in dissociated cell culture. They were divided into eight groups: negative control (NC) group with no drug administration, positive control (PC) group with H2O2 250 micrometer and other groups pretreated with propofol (P; 1, 10, 50 micrometer) or etomidate (ET; 1, 10, 50 micrometer) followed H2O2 administration. After 7 hours, cell death was assessed by morphology under the light microscope and quantified by measuring the LDH in the culture media.

RESULTS

In the light microscopic findings, the intact cells were increased in all three propofol groups compared to group PC. H2O2-induced LDH production was also significantly suppressed in all three propofol groups compared to group PC (P < 0.001). There were no significant differences in the microscopic findings and LDH production between the etomidate groups and group PC.

CONCLUSIONS

These results suggest that the propofol has protective effect on the hepatocyte against H2O2-induced oxidative stress.

Activated protein C prevents hepatic ischaemia-reperfusion injury in rats

BACKGROUND

Hepatic ischaemia-reperfusion injury (IRI) is a serious complication of liver surgery, especially extended hepatectomy and liver transplantation. Activated protein C (APC), a potent anticoagulant serine protease, has been shown to have cell-protective properties by virtue of its anti-inflammatory and anti-apoptotic activities.

METHODS

The present study was designed to examine the cytoprotective effects of APC in a 60-min warm-IRI rat model.

RESULTS

Following a single intravenous injection of APC before reperfusion, APC exerted cytoprotective effects 4 h after reperfusion, as evidenced by: (i) decreased levels of transaminase and improved histological findings of IRI, (ii) reduced infiltration and activation of neutrophils, macrophages and T cells, (iii) reduced expression of tumour necrosis factor-alpha, (iv) reduced expression of P-selectin and intracellular adhesion molecule-1, (v) inhibited coagulation and attenuated sinusoidal endothelial cell injury, (vi) improved hepatic microcirculation and (vii) decreased transferase-mediated dUTP nick end-labelling-positive cells. These effects of APC were observed 4 h but not 24 h after reperfusion. However, multiple injections of APC after reperfusion significantly decreased the levels of transaminase and the activity of myeloperoxidase, and improved histological findings of IRI 24 h after reperfusion.

CONCLUSION

These results suggest that APC is a promising therapeutic option for hepatic warm-IRI; however, multiple injections of APC are necessary to maintain its cell-protective action over the long term.

Tissue factor deficiency and PAR-1 deficiency are protective against renal ischemia reperfusion injury

Ischemia/reperfusion (IR) injury is a leading cause of acute renal failure and an important contributor to allograft damage. Tissue factor (TF) is up-regulated during IR, and TF inhibition reduces renal injury. However, the underlying mechanisms by which TF contributes to injury have not been elucidated. We postulated that TF contributes to IR injury by production of coagulation proteases and subsequent signaling by protease activated receptor (PARs). We compared renal injury after 25 minutes of bilateral renal ischemia and varying periods of reperfusion in C57BL/6 mice, those expressing low levels of TF (low-TF), hirudin-treated C57BL/6, and mice lacking either PAR-1 or PAR-2. C57BL/6 mice developed severe renal failure and died within 48 hours of reperfusion. In contrast, low-TF, hirudin-treated C57BL/6, and PAR-1-/- mice were protected from renal failure and had reduced mortality, tubular injury, neutrophil accumulation, and lower levels of the chemokines KC and MIP-2. Importantly, PAR-1-/- mice had lower chemokine levels despite up-regulation of TF and fibrin deposition. In addition, treating PAR-1-/- mice with hirudin conferred no additional benefit. Somewhat surprisingly, PAR-2 deficiency did not protect from renal failure. These experiments indicate that increased TF activity after renal IR leads to increased CXC chemokine expression and subsequent neutrophil-mediated injury predominantly by thrombin-dependent PAR-1 signaling.

Prospects of antisense oligodeoxynucleotides to alleviate renal ischaemia-reperfusion injury

Renal ischaemia-reperfusion (I/R) injury is a clinically significant problem and an invariable consequence of renal transplantation. The problem begins at the onset of acute tubular necrosis (ATN), when the transplantation takes a long ischaemic interval by using the cardiac arrest donor's kidney. In addition, the longer the ischaemic interval, the higher the incidence rate of ATN. It is clinically important that renal I/R injury is reduced. The antisense oligodeoxynucleotide (AS-ODN), developed as a therapy for intractable diseases at the gene level, has recently been established as an important method in examining specific gene functions. The authors have previously demonstrated that AS-ODN/tissue factor (TF) prevents renal I/R injury. This review discusses the efficacy of AS-ODN/TF and AS-ODN/intercellular adhesion molecule-1 as existing targets, and the potential of AS-ODN/nuclear factor-kappaB, AS-ODN/cyclooxygenase and AS-ODN/5-lipoxygenase as prospective targets.

Graft protein C entrapment is associated with reduced phagocyte activation during reperfusion in human liver transplantation

OBJECTIVE

To explore the potential anti-inflammatory role of protein C pathway in ischemia-reperfusion injury during liver transplantation.

DESIGN

Prospective, observational clinical study.

SETTING

Tertiary teaching hospital.

PATIENTS

Fifty adult patients undergoing liver transplantation for acute liver failure or chronic liver disease.

INTERVENTIONS

To assess changes occurring across the transplanted liver, samples of blood entering and leaving the graft were obtained simultaneously from portal and hepatic veins. Plasma protein C and activated protein C levels, neutrophil and monocyte CD11b and L-selectin expression, and leukocyte differential counts were measured. Postoperative liver function and outcome of transplantation were recorded.

MEASUREMENTS AND MAIN RESULTS

During reperfusion, protein C became entrapped within the graft (portal vein 49% [20-96%]; graft caval effluent 25% [12-76%], p < .001), without concomitant activated protein C outflow from the graft. Simultaneously, marked neutrophil and monocyte activation occurred within the graft. Enhanced hepatic protein C entrapment was associated with reduced neutrophil and monocyte activation (R = .377, p = .011; R = .389, p = .008, respectively) during reperfusion.

CONCLUSIONS

Protein C entrapment occurs immediately during reperfusion in the graft without concomitant activated protein C release, suggesting a shortage of activated protein C in the reperfused graft. The ongoing inflammatory response during reperfusion may lead to protein C and activated protein C utilization within the graft. Indeed, hepatic protein C entrapment is associated with reduced hepatic phagocyte activation, suggesting a regulatory role for protein C pathway in hepatic reperfusion in human liver transplantation.

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.

Early experience with two-dose daclizumab in the prevention of acute rejection in cardiac transplantation

BACKGROUND

Daclizumab is a human monoclonal antibody that binds to the interleukin-2 receptor. It has been used as induction therapy in heart transplantation with repeated administrations over several weeks. At our institution, we use a two-dose regimen of daclizumab based on its extended half-life. We sought to determine the incidence of acute rejection with 2-dose daclizumab in cardiac transplantation.

METHODS

Eighteen consecutive heart transplants performed at a single center were analyzed retrospectively. Patients received daclizumab (2 mg/kg) within 8 h of cardiac transplantation and a second dose (1 mg/kg) 2 wk thereafter. Maintenance immunosupression included mycophenolate mofetil, prednisone and either cyclosporine or tacrolimus, based on side-effect profile. The endpoint was the incidence of acute rejection as defined by a histologic grade >2 according to the classification of the International Society of Heart and Lung Transplantation.

RESULTS

Four patients had acute rejections (all were 3A) during the first 3 months post-transplantation. All four patients had rejection at the first biopsy and only two had rejection thereafter. None of the rejections were hemodynamically significant and no patients were hospitalized. All except one rejection was seen in the context of low 2-h cyclosporine levels. The two-dose regimen was easier to administer on an outpatient basis and resulted in lower cost.

CONCLUSIONS

This preliminary report suggests that induction therapy with a two-dose regimen of daclizumab appears to be safe and well tolerated in patients undergoing cardiac transplantation.

Recombinant hirudin enhances cardiac output and decreases systemic vascular resistance during reperfusion after cardiopulmonary bypass in a porcine model

OBJECTIVE

Cardiopulmonary bypass and surgical stress are accompanied by a systemic inflammatory response and activation of coagulation. Thrombin forms fibrin and activates platelets and neutrophils. Consequently, disseminated microthrombosis might increase capillary vascular resistance and thus impair reperfusion. We hypothesized that recombinant hirudin, a direct inhibitor of thrombin, could attenuate coagulation and enhance microvascular flow during reperfusion.

METHODS

Twenty pigs undergoing 60 minutes of aortic clamping and 75 minutes of normothermic perfusion were randomized in a blinded setting to receive an intravenous bolus of recombinant hirudin (10 mg, 0.4 mg/kg; n = 10) or placebo (n = 10) 15 minutes before aortic declamping and then continued with an intravenous 135-minute infusion of recombinant hirudin (3.75 mg/h, 0.15 mg/kg) or placebo. Thrombin-antithrombin complexes, activated clotting times, and several hemodynamic parameters were measured before cardiopulmonary bypass, after weaning from cardiopulmonary bypass, and at 30, 60, 90, and 120 minutes after aortic declamping. Intramucosal pH and Pco(2) were measured from the luminal surface of ileum simultaneously with arterial gas analysis at 30-minute intervals.

RESULTS

Recombinant hirudin inhibited thrombin formation after aortic declamping; at 120 minutes, thrombin-antithrombin complexes levels (microg/L, mean +/- SD) were 75 +/- 21 and 29 +/- 44 (P <.001) for placebo and pigs receiving recombinant hirudin, respectively. When compared with the placebo group, pigs receiving recombinant hirudin showed significantly higher stroke volume, cardiac output, and lower systemic vascular resistance at 60 and 90 minutes after aortic declamping (P <.05). Based on arteriomucosal Pco(2) and pH differences, progressive worsening of intestinal microcirculatory perfusion occurred in the placebo group but not in the recombinant hirudin group.

CONCLUSION

Infusion of thrombin inhibitor recombinant hirudin during reperfusion was associated with attenuated postischemia left ventricular dysfunction and decreased vascular resistance. Consequently microvascular flow was improved during ischemia-reperfusion injury. Control of thrombin formation during reperfusion may be a feasible approach to improve oxygen delivery to reperfused vascular beds.

Tissue factor antisense oligonucleotides prevent renal ischemia-reperfusion injury

BACKGROUND

Tissue factor (TF) expression is induced on macrophages and endothelial cells during the immune response. We designed an antisense (AS) phosphorothioate oligodeoxynucleotide (ODN) to specifically inhibit the expression of rat TF to study the effects of the AS ODN on renal ischemia-reperfusion injury in the rat.

METHOD

AS-1 ODN for TF was delivered intravenously to inhibit the expression of TF in endothelial cells. After 8 hr, the right kidney was harvested and the left renal artery and vein were clamped. The kidney was reperfused after 90 min of ischemia, and rats were killed at 0, 1.5, 5, 12, and 24 hr after reperfusion. TF expression was analyzed by immunohistochemical staining using monoclonal antibody.

RESULTS

In the untreated ischemic group, 0 of 20 rats survived beyond day 3. However, treatment with AS-1/TF led to 12 of 20 rats surviving beyond day 4. TF was detected on distal tubular epithelial cells, endothelial cells, and blood vessels but not on necrotic and proximal tubular epithelial cells. The necrotic area extended and encompassed nearly all of the ischemic kidney within 12 hr after reperfusion. The necrotic area and the grade of TF staining were more significantly reduced in the AS-1/TF-treated group than in the control group. Furthermore, fluorescein isothiocyanate-labeled AS-1/TF was significantly intense in tubular epithelial cells 8 hr after intravenous administration.

CONCLUSIONS

The results indicate that AS-1/TF inhibited the ischemia-reperfusion injury of the kidney. Microcirculatory incompetence resulting from microthrombus may cause the formation and development of necrosis.

Overexpression of the 78-kDa glucose-regulated protein/immunoglobulin-binding protein (GRP78/BiP) inhibits tissue factor procoagulant activity

Previous studies have demonstrated that overexpression of GRP78/BiP, an endoplasmic reticulum (ER)-resident molecular chaperone, in mammalian cells inhibits the secretion of specific coagulation factors. However, the effects of GRP78/BiP on activation of the coagulation cascade leading to thrombin generation are not known. In this study, we examined whether GRP78/BiP overexpression mediates cell surface thrombin generation in a human bladder cancer cell line T24/83 having prothrombotic characteristics. We report here that cells overexpressing GRP78/BiP exhibited significant decreases in cell surface-mediated thrombin generation, prothrombin consumption and the formation of thrombin-inhibitor complexes, compared with wild-type or vector-transfected cells. This effect was attributed to the ability of GRP78/BiP to inhibit cell surface tissue factor (TF) procoagulant activity (PCA) because conversion of factor X to Xa and factor VII to VIIa were significantly lower on the surface of GRP78/BiP-overexpressing cells. The additional findings that (i) cell surface factor Xa generation was inhibited in the absence of factor VIIa and (ii) TF PCA was inhibited by a neutralizing antibody to human TF suggests that thrombin generation is mediated exclusively by TF. GRP78/BiP overexpression did not decrease cell surface levels of TF, suggesting that the inhibition in TF PCA does not result from retention of TF in the ER by GRP78/BiP. The additional observations that both adenovirus-mediated and stable GRP78/BiP overexpression attenuated TF PCA stimulated by ionomycin or hydrogen peroxide suggest that GRP78/BiP indirectly alters TF PCA through a mechanism involving cellular Ca(2+) and/or oxidative stress. Similar results were also observed in human aortic smooth muscle cells transfected with the GRP78/BiP adenovirus. Taken together, these findings demonstrate that overexpression of GRP78/BiP decreases thrombin generation by inhibiting cell surface TF PCA, thereby suppressing the prothrombotic potential of cells.

Antisense oligonucleotide for tissue factor inhibits hepatic ischemic reperfusion injury

Tissue factor (TF) is an initiation factor for blood coagulation and its expression is induced on endothelial cells during inflammatory or immune responses. We designed an antisense oligodeoxynucleotide (AS-1/TF) for rat TF and studied its effect on hepatic ischemic reperfusion injury. AS-1/TF was delivered intravenously to Lewis rats. After 10 h, hepatic artery and portal vein were partially clamped. Livers were reperfused after 180 min and harvested. TF expression was studied using immunohistochemical staining. One of 10 rats survived in a 5-day survival rate and TF was strongly stained on endothelial cells in non-treatment group. However, by treatment with AS-1/TF, six of seven survived and TF staining was significantly reduced. Furthermore, we observed that fluorescein-labeled AS-1/TF was absorbed into endothelial cells. These results suggest that AS-1/TF can strongly suppress the expression of TF and thereby inhibit ischemic reperfusion injury to the rat liver.

The role of tissue factor in renal ischemic reperfusion injury of the rat

BACKGROUND

Tissue factor (TF) is a membrane-bound glycoprotein that is the primary cellular initiator of the blood clotting cascade and its expression is induced on macrophages and endothelial cells during the inflammatory or immune response. Tissue factor pathway inhibitor (TFPI) regulates the extrinsic pathway of blood coagulation through its ability to inhibit tissue factor activity. We studied the role of TF in the kidney following warm ischemic reperfusion and studied the effect of TFPI in vivo.

MATERIALS AND METHODS

After laparotomy of Lewis rats, the right kidney was harvested and left renal artery and vein were clamped. The kidney was reperfused after 60, 120, and 180 min of ischemia. Rats were sacrificed at 0, 1.5, 5, 12, and 24 h after reperfusion with or without TFPI treatment, and the kidney was harvested. Blood samples were collected at 0, 5, 12, and 24 h after reperfusion from the abdominal aorta. Blood urea nitrogen and kalium were monitored. TF expression was also studied by immunohistochemical staining with a monoclonal antibody (HTF-K108).

RESULTS

Histologically, the necroses of the tubular epithelial cells were observed 1.5 h after reperfusion. Immunohistochemically, TF staining was positive on the glomerular endothelial cells and stimulated monocytes but negative on the tubular epithelial cells. The necrotic area extended and encompassed almost all of the ischemic kidney by 12 h after reperfusion. TF was stained on the glomerular base membrane, the glomerular endothelial cells, and the stimulated monocytes but was not evident on the necrotic tubular epithelial cells. Fibrinogen was also observed in the glomerular endothelial cells at 5-12 h after reperfusion, while it was slight in normal tissue. With TFPI treatment, the necrotic area was narrow and TF was slightly stained on the endothelial cells.

CONCLUSIONS

These results suggest that TF plays an important role in the development of renal injury after ischemia and reperfusion. The microcirculatory incompetence due to microthrombus might cause the formation and development of the necrosis. These results also suggest that TFPI plays a key role in modulating tissue factor-dependent blood coagulation, therefore TFPI is a strong medication for prevention of ischemic reperfusion injury.

Inhibition of factor Xa suppresses the expression of tissue factor in human monocytes and lipopolysaccharide-induced endotoxemia in rats

BACKGROUND

Activated factor X (FXa) is involved in hemostasis, thrombogenesis, inflammation, and cellular immune response. Tissue factor (TF) is an initiator of blood coagulation. We investigated whether FXa induces TF expression in human peripheral monocytes and whether treatment with FXa inhibitor reduces TF expression in an experimental model of rat endotoxemia.

METHODS

Human peripheral mononuclear cells were used to determine TF expression induced by FXa. Experimental rat endotoxemia was induced by intravenous bolus injection of lipopolysaccharide (LPS). A specific FXa inhibitor, DX-9065a, was administered subcutaneously immediately after LPS injection.

RESULTS

FXa induced TF expression in monocytes without intervention of thrombin and the expression was suppressed by FXa inhibitor. In the experimental model of rat endotoxemia, TF and TF mRNA expression levels in the liver were reduced by DX-9065a. Moreover, administration of DX-9065a suppressed the rise in plasma concentrations of thrombin-antithrombin III complex (TAT) and monocyte chemoattractant protein-1 (MCP-1).

CONCLUSIONS

Our results indicated that FXa can induce TF expression in human peripheral monocytes and that inhibition of FXa reduces TF expression in the liver of rat endotoxemia. These results suggest that FXa is an important factor for TF expression in sepsis.

Beneficial effect of FR167653 on cold ischemia/reperfusion injury in rat liver transplantation

BACKGROUND

Proinflammatory cytokines such as interleukin 1-beta (IL-1beta) and tumor necrosis factor-a (TNF-alpha) play an important role in the development of hepatic ischemia/reperfusion injury. FR167653 has been characterized as a potent suppressant of IL-1beta and TNF-alpha production. The aim of this study was to evaluate the effect of FR167653 on cold ischemia/ reperfusion injury in rat liver transplantation.

METHODS

Donor livers were preserved with cold University of Wisconsin solution for 48 hr and transplanted orthotopically. Immediately after reperfusion, FR167653 (1 mg/kg, FR-treated group) or normal saline solution (control group) was administered i.v.. The severity of liver injury was determined by hepatic enzyme levels as well as by histological findings. The accumulation of IL-1beta and TNF-alpha mRNA in the liver was analyzed by semi-quantitative reverse transcription-polymerase chain reaction. Tissue factor expression was subjected to immunohistochemical analysis.

RESULTS

In the FR-treated group, release of aspartate aminotransferase and alanine aminotransferase after reperfusion was significantly lower (P<0.05 and P<0.02, respectively), and histological liver injury was less prominent, than in the control group. Accumulation of IL-1beta and TNF-alpha mRNA was suppressed in the FR-treated liver. Tissue factor expression on Kupffer cells and sinusoidal endothelial cells, marked in the control group, was almost absent in the FR-treated group. Seven-day survival in the FR-treated group (75%) was significantly better than that in the control group (12.5%) (P<0.01).

CONCLUSIONS

These results indicate that treatment with FR167653 ameliorates cold ischemia/reperfusion injury in liver transplantation.

Role of tissue factor-mediated coagulation in ischemia/ reperfusion-induced injury of Langendorf-perfused rabbit hearts

BACKGROUND

Production of oxygen free radicals, and activation of neutrophils and plasma complement contribute to myocardial reperfusion injury, but the role of coagulation has not been assessed.

OBJECTIVE

To characterize tissue-factor-mediated generation of thrombin and its association with tissue injury during reperfusion from normothermic ischemia of isolated, Langendorf-perfused rabbit hearts.

METHODS

Activation of coagulation was assessed by addition of 12% rabbit plasma and human fibrinogen to Krebs-Henseleit-buffer perfusate with measurement of levels of human fibrinopeptide A (hFPA) in the heart effluent as an index of thrombin-mediated formation of fibrin.

RESULTS

Concentrations of hFPA in the effluent were minimal during non-ischemic perfusion (5 +/- 5 ng/ml, n=6) and during 50 min of ischemia (13 +/- 3 ng/ml, n=6), but increased markedly during the first 20 min of reperfusion (to 41 +/- 29 ng/ml, P=0.03 versus before reperfusion). Addition to the perfusate of 10 microg/ml recombinant human tissue-factor-pathway inhibitor, the physiologic inhibitor of tissue-factor-mediated coagulation, abolished increases in the level of hFPA after reperfusion. However, indexes of myocardial injury manifested during reperfusion, including decrease in recovery of left ventricular pressure developed, increase in left ventricular end-diastolic pressure, and increase in activity of creatine kinase in the heart effluent, were not improved by anticoagulation with recombinant human tissue-factor-pathway inhibitor.

CONCLUSION

Our results do not support the hypothesis that coagulation plays a major role in ischemia/reperfusion injury of Langendorf-perfused rabbit hearts.

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

BACKGROUND

Clotting proteases may affect leukocyte effector function. Activation of the coagulation cascade after ischemia/reperfusion stimulates cytokine production by activated macrophages. Cytokine-induced neutrophil chemoattractant (CINC) may also be important in the pathophysiology of liver ischemia/reperfusion injury. We investigated the effects of a selective factor Xa inhibitor, DX-9065a, on CINC expression after ischemia/reperfusion in the rat liver.

METHODS

Liver ischemia was induced in rats by occluding the portal vein for 30 min. DX-9065a (9 mg/kg) was injected intravenously 5 min before vascular clamping. Serum CINC concentrations were measured by enzyme-linked immunosorbent assay. Levels of CINC mRNA in the liver were determined by Northern blot analysis. We also examined in vitro CINC production by peritoneal macrophages in response to alpha-thrombin or factor Xa.

RESULTS

Serum CINC concentrations increased and peaked 6 h after reperfusion. However, pretreatment of animals with DX-9065a resulted in significantly smaller increases in CINC after reperfusion. Pretreatment with DX-9065a also significantly reduced CINC mRNA levels in the liver after ischemia/reperfusion. In vitro CINC production by peritoneal macrophages was enhanced by alpha-thrombin, as well as factor Xa.

CONCLUSIONS

Thrombin and factor Xa stimulate CINC production by macrophages. A selective inhibitor of factor Xa, DX-9065a, attenuates neutrophil chemoattractant production after ischemia/reperfusion injury of the rat liver.

The effect of tissue factor pathway inhibitor on hepatic ischemic reperfusion injury of the rat

BACKGROUND

Tissue factor (TF) is an initiation factor for blood coagulation, and its expression is induced on macrophages and endothelial cells during the inflammatory or immune responses. In a previous study, we reported the significance of TF expression in hepatic ischemic reperfusion injury using a rat model. Recently, tissue factor pathway inhibitor (TFPI) has been discovered, and the effect of TFPI has been assessed in vivo. In this study, therefore, we studied the effect of TFPI on hepatic ischemic reperfusion injury of the rat.

METHODS

After laparotomy of Lewis rats, the branches of the hepatic artery and portal vein leading to the median, left, and caudate lobes of the liver were clamped. The liver was reperfused after 120 or 180 min of ischemia. Simultaneously, recombinant human TFPI (4 mg/kg) was injected via a superiomesenteric vein. Rats were sacrificed at 5, 12, and 24 hr after reperfusion, and liver tissues were harvested. TF expression was studied by immunohistochemical staining with the monoclonal antibody (HTF-K108).

RESULTS

Survival rates over a 5-day period were examined after the ischemic time of 120 and 180 min. Seven of 10 rats in the 120-min ischemia group (n=10), and only 1 (10%) rat of 10 in the 180-min ischemia group (n=10) survived. However, by the treatment with TFPI, all of the rats in the 120-min ischemia group (n=10), and six rats in the 180-min ischemia group (n=10) survived (P<0.05). The serum concentrations of alanine aminotransferase (ALT) and thrombin-antithrombin complex (TAT) before ischemia were 30.0+/-2.3 IU/L and 4.7+/-1.4 ng/ml, respectively (n=5). These levels showed a peak at 3-5 hr after reperfusion (ALT: 13909+/-1900 IU/L, TAT: 30.4+/-7.0 ng/ml) (P<0.01). However, both peak levels were decreased by the treatment with TFPI (ALT: 6017+/-1290 IU/L, TAT: 5.4+/-2.1 ng/ml) (P<0.01). Although TF was strongly stained on endothelial cells and Kupffer cells accumulating to the site of the necrosis in the control group, the area of the necrosis and the grade of TF staining were significantly reduced in the TFPI-treated group.

CONCLUSIONS

These results indicated that TFPI strongly inhibited the injury of the ischemic reperfusion, and confirmed that TF played a pivotal role in the development of ischemic reperfusion injury.