Effects of acute liver injury on blood coagulation

Robust coagulation activation and coagulopathy in mice with experimental acetaminophen-induced liver failure

BACKGROUND

Patients with acetaminophen (APAP)-induced acute liver failure (ALF) display both hyper- and hypocoagulable changes not necessarily recapitulated by standard hepatotoxic doses of APAP used in mice (eg, 300 mg/kg).

OBJECTIVES

We sought to examine coagulation activation in vivo and plasma coagulation potential ex vivo in experimental settings of APAP-induced hepatotoxicity and repair (300-450 mg/kg) and APAP-induced ALF (600 mg/kg) in mice.

RESULTS

APAP-induced ALF was associated with increased plasma thrombin-antithrombin complexes, decreased plasma prothrombin, and a dramatic reduction in plasma fibrinogen compared with lower APAP doses. Hepatic fibrin(ogen) deposits increased independent of APAP dose, whereas plasma fibrin(ogen) degradation products markedly increased in mice with experimental ALF. Early pharmacologic anticoagulation (+2 hours after 600 mg/kg APAP) limited coagulation activation and reduced hepatic necrosis. The marked coagulation activation evident in mice with APAP-induced ALF was associated with a coagulopathy detectable ex vivo in plasma. Specifically, prolongation of the prothrombin time and inhibition of tissue factor-initiated clot formation were evident even after restoration of physiological fibrinogen concentrations. Plasma endogenous thrombin potential was similarly reduced at all APAP doses. Interestingly, in the presence of ample fibrinogen, ∼10 times more thrombin was required to clot plasma from mice with APAP-induced ALF compared with plasma from mice with simple hepatotoxicity.

CONCLUSION

The results indicate that robust pathologic coagulation cascade activation in vivo and suppressed coagulation ex vivo are evident in mice with APAP-induced ALF. This unique experimental setting may fill an unmet need as a model to uncover mechanistic aspects of the complex coagulopathy of ALF.

Influence of Oral Dipping Tombak Smokeless Tobacco on Coagulation Profile and Platelet Counts

The goal of this paper is to investigate the influence of oral dipping of Tombak Smokeless Tobacco (SLT) on prothrombin time (PT), activated partial thromboplastin time (APTT), international normalized ratio(INR) values, and platelet counts (PLTs), in Sudanese Tombak users. An analytical cross-sectional study was conducted at Kosti health insurance hospital, Sudan, in 2019. According to the inclusion and exclusion criteria, 100 adult users of oral Tombak for three or more years were chosen randomly as a study group. Another 100 matched healthy individuals who never used Tombak were randomly selected as a comparative group. Venous blood specimens were collected in ethylene diamine tetra-acetic acid (EDTA) containers for the PLT counts using the automated haematology analyser (Sysmex, Tokyo, Japan XK-21SYSMEX) and in trisodium citrate anti-coagulant containers for coagulation tests using a co-agulometer machine analyser. Our findings show a significant decrease in PLT count mean values in the Tombak users group (212.1 × 103/mm3 ± 74.3 × 103/mm3) compared with the non-taking Tombak group mean values (243.2 × 103/mm3 ± 83.0 × 103/mm3), (p < 0.006). Both PT and APTT were significantly prolonged in Tombak users (16.03 ± 1.22 s vs. 14.44 ± 0.557 s), p < 0.001 for PT, and (41.62 ± 7.28 s vs. 34.99 ± 4.02 s), (p < 0.001) for APTT. INR mean values were significantly longer in Tombak users (1.11 ± 0.096) vs. (1.07 ± 0.66; p < 0.001). Multiple linear regression analysis findings show a significant impact of the four investigated variables, including duration of taking Tombak, age, and frequency of taking Tombak per day (p < 0.001). In conclusion, using Tombak a Smokeless Tobacco (SLT) for a long period significantly affect Platelet counts and coagulation profile.

Predictors of Deep Venous Thrombosis in Hospitalized Patients With Liver Cirrhosis in the US

Background

Patients with liver cirrhosis were previously considered as anticoagulated; thus, their risk of developing venous thromboembolism (VTE) is lower. Recently, several studies showed contradicting results regarding deep venous thrombosis (DVT) occurrence in cirrhotic patients. The aim of this study is to evaluate the prevalence and risk associated with developing DVT in hospitalized cirrhotic patients in a large US population.

Methods

We queried the commercial database Explorys (IMB Inc., Armonk, New York), an aggregate of electronic health record data from 26 US healthcare systems. After excluding patients under 20 years old, a cohort of patients with a Systematized Nomenclature of Medicine - Clinical Terms of "cirrhosis of the liver" and "inpatient care" between 2015-2019 were identified, and prevalence of DVT was calculated in the exposure and the control groups. Statistical analysis for a multivariable model was performed. Factors adjusted for include gender, race, obesity, hypoalbuminemia, diabetes mellitus, viral hepatitis, and liver malignancy.

Results

Among 9,990,290 patients who were hospitalized between 2015 and 2019, 157,400 patients had a diagnosis of liver cirrhosis. The prevalence of DVT in hospitalized patients with liver cirrhosis was 3.29% compared to 3.18% in non-cirrhotic patients. Using the multivariate analysis model, DVT was inversely associated with cirrhosis in hospitalized patients [OR: 0.921; p<0.0001] compared to patients without liver cirrhosis. Predictors of developing DVT among patients with cirrhosis were non-Caucasian race, obesity (BMI>30), liver malignancy, hypoalbuminemia, and diabetes mellitus. Cirrhotic patients due to viral hepatitis were less likely to develop DVT [OR: 0.775; p<0.001] compared to non-cirrhotic patients.

Conclusion

In this database, although the prevalence of DVT in cirrhotic hospitalized patients was slightly higher than in non-cirrhotic patients (3.29% vs. 3.18%, respectively), cirrhosis as an independent factor was associated with less risk of DVT during hospitalization. This poses a question regarding DVT prophylaxis necessity in this group of patients. Further studies are needed to clarify the benefit and risks of DVT prophylaxis in cirrhotic patients. 

Evaluation of KP-1199: a novel acetaminophen analog for hemostatic function and antinociceptive effects

BACKGROUND

Acetaminophen (APAP) is a widely self-prescribed analgesic for mild to moderate pain, but overdose or repeat doses can lead to liver injury and death. Kalyra Pharmaceuticals has developed a novel APAP analog, KP-1199, currently in Phase 1 clinical studies, which lacks hepatotoxicity. In this study, the authors evaluated the antinociceptive effect of KP-1199 on thermal injury-induced nociceptive behaviors as well as hemostatic parameters using human blood samples.

METHODS

Full-thickness thermal injury was induced in anesthetized adult male Sprague-Dawley rats. On day 7 post-injury, KP-1199 (30 and 60 mg/kg) or APAP (60 mg/kg) was administered orally. Antinociception of KP-1199 and APAP were assessed at multiple time points using Hargreaves' test. In separate experiments, human whole blood was collected and treated with either KP-1199, APAP, or Vehicle (citrate buffer) at 1× (214 μg/ml) and 10× (2140 μg/ml) concentrations. The treated blood samples were assessed for: clotting function, thrombin generation, and platelet activation.

RESULTS

APAP did not produce antinociceptive activity. KP-1199 treatment significantly increased the nociceptive threshold, and the antinociceptive activity persisted up to 3 h post-treatment. In human samples, 10× APAP caused significantly prolonged clotting times and increased platelet activation, whereas KP-1199 had caused no negative effects on either parameter tested.

CONCLUSION

These results suggest that KP-1199 possesses antinociceptive activity in a rat model of thermal injury. Since KP-1199 does not induce platelet activation or inhibit coagulation, it presents an attractive alternative to APAP for analgesia, especially for battlefield or surgical scenarios where blood loss and blood clotting are of concern.

Targeting von Willebrand factor in liver diseases: A novel therapeutic strategy?

Acute and chronic liver disease are associated with substantial alterations in the hemostatic system. Evidence from both experimental and clinical studies suggests that anticoagulants slow the progression of liver disease. Efficacy of those anticoagulant drugs is, in part, attributed to a reduction of microthrombi formation within the liver. Although anticoagulant drugs show promising results, bleeding risk associated with these drugs is an obvious drawback, particularly in patients with a complex coagulopathy driven by decreased liver function. Identifying therapies that reduce intrahepatic thrombosis with minimal bleeding risk would significantly advance the field. Among the hemostatic alterations observed in patients are substantially increased levels of the platelet-adhesive protein von Willebrand factor (VWF). In contrast, levels of A Disintegrin and Metalloproteinase with Thrombospondin motifs, the enzyme that regulates VWF activity, are significantly reduced in patients with liver disease. Highly elevated VWF levels are proposed to accelerate intrahepatic thrombus formation and thus be a driver of disease progression. Strong clinical evidence suggesting a link between liver disease and changes in VWF is now being matched by emerging mechanistic data showing a detrimental role for VWF in the progression of liver disease. This review focuses on clinical and experimental evidence supporting a connection between VWF function and the progression of acute and chronic liver diseases. Furthermore, with the recent anticipated approval of several novel therapies targeting VWF, we discuss potential strategies and benefits of targeting VWF as an innovative therapy for patients with liver disease.

Severe COVID-19 Infection Associated with Endothelial Dysfunction Induces Multiple Organ Dysfunction: A Review of Therapeutic Interventions

Since December 2019, the SARS-CoV-2 (COVID-19) pandemic has transfixed the medical world. COVID-19 symptoms vary from mild to severe and underlying chronic conditions such as pulmonary/cardiovascular disease and diabetes induce excessive inflammatory responses to COVID-19 and these underlying chronic diseases are mediated by endothelial dysfunction. Acute respiratory distress syndrome (ARDS) is the most common cause of death in COVID-19 patients, but coagulation induced by excessive inflammation, thrombosis, and disseminated intravascular coagulation (DIC) also induce death by multiple-organ dysfunction syndrome. These associations imply that maintaining endothelial integrity is crucial for favorable prognoses with COVID-19 and therapeutic intervention to support this may be beneficial. Here, we summarize the extent of heart injuries, ischemic stroke and hemorrhage, acute kidney injury, and liver injury caused by immune-mediated endothelial dysfunction that result in the phenomenon of multi-organ dysfunction seen in COVID-19 patients. Moreover, the potential therapeutic effect of angiotensin receptor blockers and angiotensin-converting enzyme inhibitors that improve endothelial dysfunction as well as the bradykinin storm are discussed.

Clinical Considerations of Coagulopathy in Acute Liver Failure

Acute liver failure (ALF) is the rapid onset of severe liver dysfunction, defined by the presence of hepatic encephalopathy and impaired synthetic function (international normalized ratio of ≥1.5) in the absence of underlying liver disease. The elevated international normalized ratio value in ALF is often misinterpreted as an increased hemorrhagic tendency, which can lead to inappropriate, prophylactic transfusions of blood products. However, global assessments of coagulopathy via viscoelastic tests or thrombin generation assay suggest a reestablished hemostatic, or even hypercoagulable, status in patients with ALF. Although the current versions of global assays are not perfect, they can provide more nuanced insights into the hemostatic system in ALF than the conventional measures of coagulopathy.

SARS-CoV-2 cell entry receptor ACE2 mediated endothelial dysfunction leads to vascular thrombosis in COVID-19 patients

Several studies have described unusually high incidence of vascular thrombosis in coronavirus disease-2019 (COVID-19) patients. Pathogenesis of the vascular thrombosis in COVID-19 is least understood for now and presents a challenge to the treating physicians. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative pathogen for COVID-19, has been shown to bind to angiotensin converting enzyme 2 (ACE2) protein in human epithelial cells which facilitates its entry in the organ and mediate tissue specific pathogenesis. For ACE2 mediated cell entry of the SARS-CoV-2, co-expression of one more protein-Transmembrane protease serine 2 (TMPRSS2) is essential. Existing studies suggested significant expression of ACE2 and TMPRSS2 in human vascular endothelium. Vascular endothelial dysfunction can potentially activate coagulation cascade eventually resulting in thrombosis. ACE2 has proven role in the maintenance of endothelial integrity inside the vessels. Existing in situ evidence for SARS-CoV-1 (the causative agent for SARS pandemic of 2002, which shared ACE2 as cell entry receptor) suggested that virus binding can downregulate ACE2, thus can induce endothelial dysfunction. Recently, in situ evidence has been presented that SARS-CoV-2 can infect cells in engineered human vascular endothelium, which can be effectively blocked by using clinical-grade recombinant human ACE2. Based on the circumstantial evidence present in the literature, we propose a SARS-CoV-2 cell entry receptor ACE2 based mechanism for vascular thrombosis in COVID-19 patients.

Hemostatic Changes in Patients with COVID-19: A Meta-Analysis with Meta-Regressions

BACKGROUND

Complications of coronavirus disease 2019 (COVID-19) include coagulopathy. We performed a meta-analysis on the association of COVID-19 severity with changes in hemostatic parameters.

METHODS

Data on prothrombin time (PT), activated partial thromboplastin time (aPTT), D-Dimer, platelets (PLT), or fibrinogen in severe versus mild COVID-19 patients, and/or in non-survivors to COVID-19 versus survivors were systematically searched. The standardized mean difference (SMD) was calculated.

RESULTS

Sixty studies comparing 5487 subjects with severe and 9670 subjects with mild COVID-19 documented higher PT (SMD: 0.41; 95%CI: 0.21, 0.60), D-Dimer (SMD: 0.67; 95%CI: 0.52, 0.82), and fibrinogen values (SMD: 1.84; 95%CI: 1.21, 2.47), with lower PLT count (SMD: -0.74; 95%CI: -1.01, -0.47) among severe patients. Twenty-five studies on 1511 COVID-19 non-survivors and 6287 survivors showed higher PT (SMD: 0.67; 95%CI: 0.39, 0.96) and D-Dimer values (SMD: 3.88; 95%CI: 2.70, 5.07), with lower PLT count (SMD: -0.60, 95%CI: -0.82, -0.38) among non-survivors. Regression models showed that C-reactive protein values were directly correlated with the difference in PT and fibrinogen.

CONCLUSIONS

Significant hemostatic changes are associated with COVID-19 severity. Considering the risk of fatal complications with residual chronic disability and poor long-term outcomes, further studies should investigate the prognostic role of hemostatic parameters in COVID-19 patients.

Acute Fatty Liver of Pregnancy: Pathophysiology, Anesthetic Implications, and Obstetrical Management

A narrative review of the pathophysiology, diagnosis, management, delivery implications, obstetric anesthesia care, and potential critical care needs in patients presenting with acute fatty liver of pregnancy.

Liver Diseases and the Hemostasis (Rewiew) Part 1. Non-Cholestatic Diseases of the Liver and Hemostasis

In liver diseases, most commonly in the terminal stage of liver failure, a variety of hemostatic defects affecting almost all parts of the blood coagulation system are developing. This leads to diminishing the capabilities of patients with liver diseases to correctly maintain the hemostatic balance.The severity of hemostatic disorders depends on the nosological form and degree of a liver damage. Depending on the imbalance of the hemostasis system and accumulated clinical/laboratory data, patients with liver diseases can be subdivided into three groups as exhibiting: 1. non-cholestatic liver damage; 2. cholestatic liver damage and 3. liver damage of vascular origin.The first part of the review discusses multiple alterations in the hemostasis system in patients with noncholestatic liver diseases, which are commonly accompanied by hypocoagulation.

Elimination of Intracellular Calcium Overload by BAPTA-AM-Loaded Liposomes: A Promising Therapeutic Agent for Acute Liver Failure

In the past few decades, intracellular calcium overload has been shown to induce cell death through multiple signaling pathways. In this study, we used BAPTA-AM, a well-known membrane-permeable Ca²⁺ chelator, to prevent cell injury by allaying the intracellular calcium overload. We explored the clinical potentials of BAPTA-AM-loaded liposome (BAL) in the treatment of the acute liver failure (ALF) mouse model, which is characterized by severe hepatic necrosis and apoptosis. We discovered that BAL can significantly inhibit D-GalN-induced LO2 cell damage as it increased cell viability by 60% and downregulated the LPS-stimulated inflammatory response in RAW 264.7 macrophages by reversing the morphological change and modulating TNF-α and NF-κB expressions. Through systemic administration, BAL can rapidly accumulate in damaged liver tissue and exhibit excellent treatment effects on the D-GalN/LPS-induced ALF mouse model, including elevation of the survival rate (from 10 to 80%), recovery of normal liver indexes and liver health indicators, improvement of liver blood microcirculation (increased the blood flow volume by 80% and flow rate by 60%), and blood coagulation. The underlying hepatoprotective effect of BAL is presumably based on the antinecrosis and antiapoptosis abilities attributed to its inhibition on oxidative stress, restriction on TNF-α receptor, and mitochondria-mediated apoptotic pathway by effectively clearing the overloaded intercellular calcium. BAL holds great potential as a new therapeutic strategy for ALF treatment, and its prominent cell rescue ability provides ample opportunities for the treatment of many other diseases that are characterized by rapid and massive cell damage.

Acute Liver Failure: Mechanisms of Disease and Multisystemic Involvement

Acute liver failure is accompanied by a pathologic syndrome common to numerous different etiologies of liver injury. This acute liver failure syndrome leads to potentially widespread devastating end-organ consequences. Systemic dysregulation and dysfunction is likely propagated via inflammation as well as underlying hepatic failure itself. Decoding the mechanisms of the disease process and multisystemic involvement of acute liver failure offers potential for targeted treatment opportunities and improved clinical outcomes in this sick population.

Fibrin(ogen) drives repair after acetaminophen-induced liver injury via leukocyte αMβ2 integrin-dependent upregulation of Mmp12

BACKGROUND & AIMS

Acetaminophen (APAP)-induced liver injury is coupled with activation of the blood coagulation cascade and fibrin(ogen) accumulation within APAP-injured livers of experimental mice. We sought to define the role of fibrin(ogen) deposition in APAP-induced liver injury and repair.

METHODS

Wild-type, fibrinogen-deficient mice, mutant mice with fibrin(ogen) incapable of binding leukocyte αMβ2 integrin (Fibγ390-396A mice) and matrix metalloproteinase 12 (Mmp12)-deficient mice were fasted, injected with 300mg/kg APAP i.p. and evaluated at a range of time-points. Plasma and liver tissue were analyzed. Rescue of Fibγ390-396A mice was carried out with exogenous Mmp12. To examine the effect of the allosteric leukocyte integrin αMβ2 activator leukadherin-1 (LA-1), APAP-treated mice were injected with LA-1.

RESULTS

In wild-type mice, APAP overdose increased intrahepatic levels of high molecular weight cross-linked fibrin(ogen). Anticoagulation reduced early APAP hepatotoxicity (6h), but increased hepatic injury at 24h, implying a protective role for coagulation at the onset of repair. Complete fibrin(ogen) deficiency delayed liver repair after APAP overdose, evidenced by a reduction of proliferating hepatocytes (24h) and unresolved hepatocellular necrosis (48 and 72h). Fibγ390-396A mice had decreased hepatocyte proliferation and increased multiple indices of liver injury, suggesting a mechanism related to fibrin(ogen)-leukocyte interaction. Induction of Mmp12, was dramatically reduced in APAP-treated Fibγ390-396A mice. Mice lacking Mmp12 displayed exacerbated APAP-induced liver injury, resembling Fibγ390-396A mice. In contrast, administration of LA-1 enhanced hepatic Mmp12 mRNA and reduced necrosis in APAP-treated mice. Further, administration of recombinant Mmp12 protein to APAP-treated Fibγ390-396A mice restored hepatocyte proliferation.

CONCLUSIONS

These studies highlight a novel pathway of liver repair after APAP overdose, mediated by fibrin(ogen)-αMβ2 integrin engagement, and demonstrate a protective role of Mmp12 expression after APAP overdose.

LAY SUMMARY

Acetaminophen overdose leads to activation of coagulation cascade and deposition of high molecular weight cross-linked fibrin(ogen) species in the liver. Fibrin(ogen) is required for stimulating liver repair after acetaminophen overdose. The mechanism whereby fibrin(ogen) drives liver repair after acetaminophen overdose requires engagement of leukocyte αMβ2 integrin and subsequent induction of matrix metalloproteinase 12.

Emerging strategies for the treatment of patients with acute hepatic failure

PURPOSE OF REVIEW

The objective of this article is to review the latest developments related to the treatment of patients with acute liver failure (ALF).

RECENT FINDINGS

As the treatment of ALF has evolved, there is an increasing recognition regarding the risk of intracranial hypertension related to advanced hepatic encephalopathy. Therefore, there is an enhanced emphasis on neuromonitoring and therapies targeting intracranial hypertension. Also, new evidence implicates systemic proinflammatory cytokines as an etiology for the development of multiorgan system dysfunction in ALF; the recent finding of a survival benefit in ALF with high-volume plasmapheresis further supports this theory.

SUMMARY

Advances in the critical care management of ALF have translated to a substantial decrease in mortality related to this disease process. The extrapolation of therapies from general neurocritical care to the treatment of ALF-induced intracranial hypertension has resulted in improved neurologic outcomes. In addition, recognition of the systemic inflammatory response and multiorgan dysfunction in ALF has guided current treatment recommendations, and will provide avenues for future research endeavors. With respect to extracorporeal liver support systems, further randomized studies are required to assess their efficacy in ALF, with attention to nonsurvival end points such as bridging to liver transplantation.

Bleeding Risk and Management in Interventional Procedures in Chronic Liver Disease

The coagulopathy of liver disease is distinctly different from therapeutic anticoagulation in a patient. Despite stable elevated standard clot-based coagulation assays, nearly all patients with stable chronic liver disease (CLD) have normal or increased clotting. Common unfamiliarity with the limitations of these assays in CLD may lead to inappropriate and sometimes harmful interventions, including blood product transfusions before a procedure. Knowledge of the distinct hemostatic alterations in CLD can allow identification of the small subset of patients with clinically significant coagulopathy who can benefit from hematologic optimization before invasive procedures.

Role of hemostatic factors in hepatic injury and disease: animal models de-liver

Chronic liver damage is associated with unique changes in the hemostatic system. Patients with liver disease often show a precariously rebalanced hemostatic system, which is easily tipped towards bleeding or thrombotic complications by otherwise benign stimuli. In addition, some clinical studies have shown that hemostatic system components contribute to the progression of liver disease. There is a strong basic science foundation for clinical studies with this particular focus. Chronic and acute liver disease can be modeled in rodents and large animals with a variety of approaches, which span chronic exposure to toxic xenobiotics, diet-induced obesity, and surgical intervention. These experimental approaches have now provided strong evidence that, in addition to perturbations in hemostasis caused by liver disease, elements of the hemostatic system have powerful effects on the progression of experimental liver toxicity and disease. In this review, we cover the basis of the animal models that are most often utilized to assess the impact of the hemostatic system on liver disease, and highlight the role that coagulation proteases and their targets play in experimental liver toxicity and disease, emphasizing key similarities and differences between models. The need to characterize hemostatic changes in existing animal models and to develop novel animal models recapitulating the coagulopathy of chronic liver disease is highlighted. Finally, we emphasize the continued need to translate knowledge derived from highly applicable animal models to improve our understanding of the reciprocal interaction between liver disease and the hemostatic system in patients.

Hemorrhagic Complications Following Abdominal Paracentesis in Acute on Chronic Liver Failure: A Propensity Score Analysis

ABSTARCT

Patients with acute on chronic liver failure (ACLF) usually present with severe coagulopathy. Abdominal paracentesis is often performed in these patients. The aim of this study was to analyze the prevalence of hemorrhagic events after paracentesis and the predictive factors of this condition in ACLF populations.ACLF patients who underwent paracentesis were retrospectively enrolled within a 5-year period. A propensity score (PS) matching analysis was used to select matched cases from the overall nonhemorrhagic group to be used as the control group. Hemorrhagic complications and risk factors were examined using logistic regression analysis.A total of 602 abdominal paracenteses were carried out on 218 ACLF patients and 18 (2.99%) hemorrhagic complications were identified. The MELD scores were higher in hemorrhagic patients than overall patients before PS matching (25.77±6.65 vs 21.04 ± 7.93, P = 0.013). We matched 18 cases with bleeding events to 72 unique cases without. The hemorrhagic group had significantly lower fibrinogen levels and higher PT levels than nonhemorrhagic cases. Logistic regression analysis revealed that lower fibrinogen levels could independently predict hemorrhagic complications (OR: 0.128, 95% CI: 0.023-0.697, P = 0.017). The best cut-off value for reliable measurement of fibrinogen levels was 0.70 g/L, with a sensitivity of 76.4% and a specificity of 80.0%. The area under curve was 0.733 (95% CI 0.604-0.862, P value 0.002).Severe hemorrhagic complications occur more commonly in ALCF patients than previously thought. A low fibrinogen level is an independent predictor of bleeding events in patients with MELD >25.

Coagulation in liver toxicity and disease: role of hepatocyte tissue factor

The liver is the primary source of a number of circulating coagulation factors, and acute liver injury and chronic liver disease are each associated with alterations in blood coagulation. Current views of the connection between liver injury and coagulation extend beyond the impact of liver disease on synthesis of coagulation factors to include a role for coagulation factor activity in the initiation and progression of liver disease. Mechanisms of coagulation initiation in liver disease are not completely understood. Compared to other tissues, liver expresses very low levels of tissue factor (TF). Recent studies indicate that expression of TF by hepatocytes comprises the majority of liver procoagulant activity, and that hepatocyte TF activates coagulation induced by liver injury. This review will briefly cover the expression and regulation of TF by hepatocytes, the role of TF in coagulation triggered by liver toxicity, and the contribution of coagulation activity to the progression of liver disease.

Evidence of rebalanced coagulation in acute liver injury and acute liver failure as measured by thrombin generation

BACKGROUND & AIMS

Patients with liver disease often show profound abnormalities in their haemostatic system. Studies using thrombin generation demonstrate rebalanced coagulation in patients with chronic liver disease. Our aim was to evaluate the haemostatic profile in patients with acute liver injury/failure (ALI/ALF) compared with healthy controls.

METHODS

Thrombin generation was measured in the presence and absence of thrombomodulin (TM) to activate protein C (PC) with endogenous thrombin potential (ETP; the area under the thrombin generation curve) a key parameter. Routine coagulation assays were also performed.

RESULTS

Thirty two patients with ALI/ALF and 40 controls were recruited. Patients had grossly abnormal coagulation profiles with decreased pro- and anticoagulant factors compared with controls (P < 0.001 for all comparisons), except for median Factor VIII which was increased 247 U/dl [interquartile range: 214-347] in patients compared with 120 U/dl [97-139; P < 0.001] in controls. Mean ETP was significantly lower in patients 886 nM.min (± 436) compared with controls 1596 nM.min (± 259; P < 0.001). However, when the assay was repeated with TM to activate PC, there was no significant difference in mean ETP + TM between patients and controls (632 ± 418 vs 709 ± 301 nM.min respectively; P = 0.666). Furthermore, the ETP ratio (ETP + TM/ETP) was significantly higher in patients 0.89 (0.60-0.97) compared with controls 0.48 (0.3-0.6; P = 0.002) and negatively correlated with PC (R = -0.487, P = 0.003) and Factor V (R = -0.431, P = 0.01).

CONCLUSION

ALI/ALF patients have normal ETP in the presence of TM. This supports rebalanced coagulation mediated by acquired PC resistance because of the reduction in PC, Factor V and concomitant increase in Factor VIII.

Erythrocytic phosphatidylserine exposure and hemostatic alterations in β-thalassemia intermediate patients

INTRODUCTION

Hypercoagulable state is one of the common findings in beta-thalassemia intermedia (β-TI), particularly in splenectomized patients, with infrequent blood transfusion. Abnormality of the red blood cells (RBC) membrane due to oxidative damage is suggestive of possible etiologies. Membrane lipid peroxidation increases the exposure of phosphatidylserine (PS) that plays a role in the activation of coagulation factors V and X, subsequently initiating thrombosis. Our aim of this study was to find the probable correlation of the alteration of the PS on the RBC outer membrane with the hypercoagulable state in the β-TI patients.

MATERIALS AND METHODS

Our cross-sectional study was conducted on 39 splenectomized β-TI patients and 38 age-matched healthy controls. The mean age was 37 years. Analysis of the PS exposure on the RBCs was performed by fluorescein isothiocyanate (FITC) conjugated AV protein. Measurement of the coagulation factors X, V and antithrombin III (AT-III) was performed. We also checked the D-dimer levels. Analysis was performed by SPSS16.

RESULTS

Fluorescence of FITC-Annexin V labeling on patients RBCs were higher than healthy controls; (2.8 ± 2.2%) of the patients versus (0.4 ± 0.18%) in the control group and was statistically significant (P < 0.05). Mean levels of factor X and AT-III of the patients as compared with the control group decreased and showed significant difference (P < 0.05).

CONCLUSIONS

Circulation of thalassemic RBCs, which abnormally possess PS on RBC membrane outer surface, suggests the possibility of the gradual consumption of the coagulation factors in the presence of a chronic coagulability state.

Elevated levels of the long pentraxin 3 in paracetamol-induced human acute liver injury

OBJECTIVES

Pentraxin 3 (PTX3) is a long pentraxin with diverse humoral innate immune functions. The aims of this study were to measure levels of PTX3 and C-reactive protein (CRP), a hepatocyte-derived short pentraxin, in patients after acute liver injury.

METHODS

PTX3 and CRP levels were measured in a total of 60 patients [48 paracetamol overdose (POD), 12 non-POD]. PTX3 expression was assessed by immunohistochemical analysis in explanted liver tissue.

RESULTS

Admission PTX3 levels were significantly higher in POD acute liver failure (ALF) patients compared with POD non-ALF patients (P=0.0005) and non-POD patients (P=0.004). PTX3 levels in POD patients who died or required orthotopic liver transplantation (OLT, n=14) were significantly higher compared with those in spontaneous survivors (n=34, P=0.0011). The area under the receiver operator characteristic for PTX3 for death/OLT in POD patients was 0.80 (95% confidence interval 0.67-0.93). PTX3 levels were significantly higher in those POD patients who developed the systemic inflammatory response syndrome (P=0.001). Conversely, admission CRP levels were significantly lower in POD compared with non-POD patients (P=0.011), with no significant differences between survivors and nonsurvivors. After emergency OLT, PTX3 levels fell markedly; in contrast, CRP levels rapidly increased. Immunohistochemical analysis showed PTX3 expression in sinusoidal lining cells of a normal liver, infiltrating inflammatory cells in patients with ALF, and in a membranous distribution on injured hepatocytes in POD patients.

CONCLUSION

Increased PTX3 levels are associated with adverse outcomes following POD, suggesting that the humoral innate immune system plays an underrecognized role in this condition.

Blood loss, predictors of bleeding, transfusion practice and strategies of blood cell salvaging during liver transplantation

Blood loss during liver transplantation (OLTx) is a common consequence of pre-existing abnormalities of the hemostatic system, portal hypertension with multiple collateral vessels, portal vein thrombosis, previous abdominal surgery, splenomegaly, and poor “functional” recovery of the new liver. The intrinsic coagulopathic features of end stage cirrhosis along with surgical technical difficulties make transfusion-free liver transplantation a major challenge, and, despite the improvements in understanding of intraoperative coagulation profiles and strategies to control blood loss, the requirements for blood or blood products remains high. The impact of blood transfusion has been shown to be significant and independent of other well-known predictors of posttransplant-outcome. Negative effects on immunomodulation and an increased risk of postoperative complications and mortality have been repeatedly demonstrated. Isovolemic hemodilution, the extensive utilization of thromboelastogram and the use of autotransfusion devices are among the commonly adopted procedures to limit the amount of blood transfusion. The use of intraoperative blood salvage and autologous blood transfusion should still be considered an important method to reduce the need for allogenic blood and the associated complications. In this article we report on the common preoperative and intraoperative factors contributing to blood loss, intraoperative transfusion practices, anesthesiologic and surgical strategies to prevent blood loss, and on intraoperative blood salvaging techniques and autologous blood transfusion. Even though the advances in surgical technique and anesthetic management, as well as a better understanding of the risk factors, have resulted in a steady decrease in intraoperative bleeding, most patients still bleed extensively. Blood transfusion therapy is still a critical feature during OLTx and various studies have shown a large variability in the use of blood products among different centers and even among individual anesthesiologists within the same center. Unfortunately, despite the large number of OLTx performed each year, there is still paucity of large randomized, multicentre, and controlled studies which indicate how to prevent bleeding, the transfusion needs and thresholds, and the “evidence based” perioperative strategies to reduce the amount of transfusion.

Hepatocyte tissue factor activates the coagulation cascade in mice

In this study, we characterized tissue factor (TF) expression in mouse hepatocytes (HPCs) and evaluated its role in mouse models of HPC transplantation and acetaminophen (APAP) overdose. TF expression was significantly reduced in isolated HPCs and liver homogenates from TF(flox/flox)/albumin-Cre mice (HPC(ΔTF) mice) compared with TF(flox/flox) mice (control mice). Isolated mouse HPCs expressed low levels of TF that clotted factor VII-deficient human plasma. In addition, HPC TF initiated factor Xa generation without exogenous factor VIIa, and TF activity was increased dramatically after cell lysis. Treatment of HPCs with an inhibitory TF antibody or a cell-impermeable lysine-conjugating reagent prior to lysis substantially reduced TF activity, suggesting that TF was mainly present on the cell surface. Thrombin generation was dramatically reduced in APAP-treated HPC(ΔTF) mice compared with APAP-treated control mice. In addition, thrombin generation was dependent on donor HPC TF expression in a model of HPC transplantation. These results suggest that mouse HPCs constitutively express cell surface TF that mediates activation of coagulation during hepatocellular injury.

Unc93B1 restricts systemic lethal inflammation by orchestrating Toll-like receptor 7 and 9 trafficking

Toll-like receptor-7 (TLR7) and 9, innate immune sensors for microbial RNA or DNA, have been implicated in autoimmunity. Upon activation, TLR7 and 9 are transported from the endoplasmic reticulum (ER) to endolysosomes for nucleic acid sensing by an ER-resident protein, Unc93B1. Little is known, however, about a role for sensor transportation in controlling autoimmunity. TLR9 competes with TLR7 for Unc93B1-dependent trafficking and predominates over TLR7. TLR9 skewing is actively maintained by Unc93B1 and reversed to TLR7 if Unc93B1 loses preferential binding via a D34A mutation. We here demonstrate that mice harboring a D34A mutation showed TLR7-dependent, systemic lethal inflammation. CD4(+) T cells showed marked differentiation toward T helper 1 (Th1) or Th17 cell subsets. B cell depletion abolished T cell differentiation and systemic inflammation. Thus, Unc93B1 controls homeostatic TLR7 activation by balancing TLR9 to TLR7 trafficking.

Hemostasis and thrombosis in patients with liver disease: the ups and downs

Patients with chronic or acute liver failure frequently show profound abnormalities in their hemostatic system. Whereas routine laboratory tests of hemostasis suggest these hemostatic alterations result in a bleeding diathesis, accumulating evidence from both clinical and laboratory studies suggest that the situation is more complex. The average patient with liver failure may be in hemostatic balance despite prolonged routine coagulation tests, since both pro- and antihemostatic factors are affected, the latter of which are not well reflected in routine coagulation testing. However, this balance may easily tip towards a hypo- or hypercoagulable situation. Indeed, patients with liver disease may encounter both hemostasis-related bleeding episodes as well as thrombotic events. During the 3rd International Symposium on Coagulopathy and Liver disease, held in Groningen, The Netherlands (18-19 September 2009), a multidisciplinary panel of experts critically reviewed the current data concerning pathophysiology and clinical consequences of hemostatic disorders in patients with liver disease. Highlights of this symposium are summarized in this review.

Relationship between acquired deficiency of vitamin K-dependent clotting factors and hemorrhage

This study examined the changes of activities of vitamin K-dependent clotting factors (VKDCF) under various pathological conditions and explored the relationship between acquired deficiency of VKDCFs and hemorrhage. Clinical data of 35 patients who were diagnosed as having acquired deficiency of VKDCF were retrospectively analyzed. Coagulation factors involved in the intrinsic and extrinsic pathways were detected in these patients and 41 control subjects. The results showed that the average activities of VKDCFs were decreased in the patients in comparison to the control subjects and significantly increased after treatment of these patients with vitamin K and blood products. Multivariate regression analysis indicated that decreased activity of VKDCF was not an independent risk factor for bleeding disorders owing to deficiency or metabolic disturbance of vitamin K. It was concluded that acquired deficiency of VKDCF occurs under a variety of pathologic conditions and is closely associated with hemorrhagic events. Administration of vitamin K and transfusion of blood products containing high concentrations of VKDCFs helps alleviate the hemorrhagic diseases.

Review article: the current management of acute liver failure

BACKGROUND

Acute liver failure is a devastating clinical syndrome with a persistently high mortality rate despite critical care advances. Orthotopic liver transplantation (OLT) is a life-saving treatment in selected cases, but effective use of this limited resource requires accurate prognostication because of surgical risks and the requirement for subsequent life-long immunosuppression.

AIM

To review the aetiology of acute liver failure, discuss the evidence behind critical care management strategies and examine potential treatment alternatives to OLT.

METHODS

Literature review using Ovid, PubMed and recent conference abstracts.

RESULTS

Paracetamol remains the most common aetiology of acute liver failure in developed countries, whereas acute viral aetiologies predominate elsewhere. Cerebral oedema is a major cause of death, and its prevention and prompt recognition are vital components of critical care support, which strives to provide multiorgan support and 'buy time' to permit either organ regeneration or psychological and physical assessment prior to acquisition of a donor organ. Artificial liver support systems do not improve mortality in acute liver failure, whilst most other interventions have limited evidence bases to support their use.

CONCLUSION

Acute liver failure remains a truly challenging condition to manage, and requires early recognition and transfer of patients to specialist centres providing intensive, multidisciplinary input and, in some cases, OLT.

Lactobacillus casei: influence on the innate immune response and haemostatic alterations in a liver-injury model

Lactobacilllus casei CRL 431 has the ability to modulate the local and systemic immune responses, which are significantly involved in liver injury caused by hepatotoxins. This work was conducted to determine whether L. casei has a preventive effect on the hepatic damage undergone during an acute liver injury (ALI).

METHODS

ALI was induced by an intraperitoneal injection of d-galactosamine (D-Gal). Different groups of mice received 1x 109 L. casei cells/day/mouse for 2 days before D-Gal injection. Blood and liver samples were obtained 0, 6, 12, and 24 h after D-Gal administration.

RESULTS

D-Gal induced increases in serum aminotransferases, reduced the number of blood leukocytes, enhanced neutrophil myeloperoxidase activity, increased dead cells, and altered prothrombin time and plasma fibrinogen levels. The preventive treatment with L. casei for 2 days modulated the innate immune response. This effect was shown by the earlier normalization of white blood cell counts, myeloperoxidase activity and aminotransferases levels. However, the haemostatic parameters were only partially recovered. The favourable effects obtained could be due to the capacity of L. casei to moderate the inflammatory response at the site of the injury with less damage to liver tissue.

Gene expression profiling in rat liver treated with various hepatotoxic-compounds inducing coagulopathy

A large-scale transcriptome database of rat liver (TG-GATEs) has been established by the Toxicogenomics Project in Japan. In the present study, we focused on 8 hepatotoxic compounds within TG-GATEs, i.e., clofibrate, omeprazole, ethionine, thioacetamide, benzbromarone, propylthiouracil, Wy-14,643 and amiodarone, which induced coagulation abnormalities. Aspirin was selected as a reference compound that directly causes coagulation abnormality, but not through liver toxicity. In blood chemical examinations, for all the coagulopathic compounds there was little elevation of aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT), suggesting no severe cell death by treatment with the compounds. We extracted 344 probe sets from the data for these 8 typical drugs, which induced this phenotype at any time from 3 to 28 days of repeated administration. Principal component analysis using these probe sets clearly separated dose- and time-dependent clusters of the treated groups from their controls, except aspirin and propylthiouracil, both of which were considered to cause coagulopathy not due to their hepatotoxicity but due to their direct effects on the blood coagulation system. Reviewing the extracted genes, changes in lipid metabolism were found to be dominant. Genes related to blood coagulation were generally down-regulated by these drugs except that vitamin K epoxide reductase complex subunit 1 (Vkorc1) like 1, a paralogous gene of Vkorc1, was up-regulated. As expected, expression changes of these genes were least prominent in aspirin or propylthiouracil-treated liver. We concluded that these probe sets could be a good starting point in developing mechanism-based biomarkers for diagnosis or prognosis of hepatotoxicity-related coagulation abnormalities in the early stage of drug development.

Urinary trypsin inhibitor protects against liver injury and coagulation pathway dysregulation induced by lipopolysaccharide/D-galactosamine in mice

Urinary trypsin inhibitor (UTI), a serine protease inhibitor, has been widely used for patients with inflammatory disorders including disseminated intravascular coagulation, shock, and pancreatitis in Japan. Our recent studies using UTI-null (-/-) mice have shown that UTI protects against systemic inflammatory responses and acute lung injury. However, the role of UTI in liver injury has not been elucidated. This study determined the contribution of UTI to liver injury and coagulatory disturbance induced by lipopolysaccharide and D-galactosamine (LPS/D-GalN) using UTI (-/-) and wild-type (WT) mice. LPS/D-GalN treatment caused severe liver injury characterized by neutrophilic inflammation, hemorrhagic change, necrosis, and apoptosis, which was more prominent in UTI (-/-) than in WT mice. In both genotypes of mice, LPS/D-GalN challenge caused elevations of aspartate amino-transferase and alanine amino-transferase, prolongation of the prothrombin and activated partial thromboplastin time, and decreases in fibrinogen and platelet counts, as compared with vehicle challenge. These changes, however, were significantly greater in UTI (-/-) than in WT mice. Circulatory levels of tumor necrosis factor (TNF)-alpha (P<0.05) and interferon (IFN)-gamma were also greater in UTI (-/-) than in WT mice after LPS/D-GalN challenge. These results suggest that UTI protects against severe liver injury and subsequent coagulatory disturbance induced by LPS/D-GalN, which was mediated, at least partly, through the suppression of TNF-alpha production along with its antiprotease activity.

Heparin-like effect contributes to the coagulopathy in patients with acute liver failure undergoing liver transplantation

INTRODUCTION

Liver transplantation (LT) in cirrhotics is characterized by severe coagulopathy, associated with a well documented heparin-like effect (HLE) seen by thromboelastography (TEG) after reperfusion. The amount of HLE present in patients with acute liver failure (ALF) and its role in their bleeding tendency before LT has not been investigated.

AIM

To investigate the presence and extent of HLE in patients with ALF undergoing LT and to compare the extent of HLE in this group with a group of cirrhotics undergoing LT.

MATERIAL AND METHODS

Ten consecutive ALF and 10 cirrhotic patients undergoing LT were included. TEG (with and without heparinase I), surrogate total thrombin generation (TTG) derived by TEG and haemodynamic variables were recorded for every stage of the LT. HLE was defined as a correction of r+k times on TEG of more than 50% by the addition of heparinase I.

RESULTS

Before incision, patients with ALF showed a significantly greater HLE compared with patients with cirrhosis (r+k time: 66 min corrected to 29 vs 45 min corrected to 32 min, P=0.001). After reperfusion, all the patients showed extensive HLE, without any difference between the two groups. Despite the greater HLE, patients with ALF showed similar TTG compared with the cirrhotic group. By the end of the operation, the extent of the HLE was greatly reduced in both the groups.

CONCLUSIONS

Before transplantation, patients with ALF have a greater HLE than patients with liver cirrhosis. However, this did not affect the thrombin generation calculated by TEG and resolved after transplantation.

Coagulopathy of acute liver failure

Coagulopathy is an essential component of the acute liver failure (ALF) syndrome and reflects the central role of liver function in hemostasis. ALF is a syndrome characterized by the development of hepatic encephalopathy and coagulopathy within 24 weeks of the onset of acute liver disease. Coagulopathy in this setting is a useful prognostic tool in ALF and a dynamic indicator of the hepatic function. If severe, it can be associated with bleeding and is commonly a major obstacle to the performance of invasive procedures in patients with ALF. This review focuses on the epidemiology, pathophysiology, presentation, evaluation, and management of coagulopathy in ALF.

Hypercoagulation in liver disease

The coagulopathy of liver disease is complex and often unpredictable. Despite clear evidence of an increased tendency for bleeding in patients who have cirrhosis, many circumstances also promote local and systemic hypercoagulable states. The consequences of hypercoagulability include the obvious morbidity and mortality of portal vein thrombosis, deep vein thrombosis, and pulmonary embolism, but possibly also include other end-organ syndromes, such as portopulmonary hypertension, hepatorenal syndrome, and spontaneous bacterial peritonitis. A more subtle contribution also could be responsible for progression of early fibrosis to decompensated cirrhosis. Future research is needed to elucidate specific mechanistic pathways that might lead to local hypercoagulation and the clinical interventions that might prevent morbidity and mortality related to hypercoagulation in patients who have cirrhosis.

New insights into the coagulopathy of liver disease and liver transplantation

The liver is an essential player in the pathway of coagulation in both primary and secondary haemostasis. Only von Willebrand factor is not synthetised by the liver, thus liver failure is associated with impairment of coagulation. However, recently it has been shown that the delicate balance between pro and antithrombotic factors synthetised by the liver might be reset to a lower level in patients with chronic liver disease. Therefore, these patients might not be really anticoagulated in stable condition and bleeding may be caused only when additional factors, such as infections, supervene. Portal hypertension plays an important role in coagulopathy in liver disease, reducing the number of circulating platelets, but platelet function and secretion of thrombopoietin have been also shown to be impaired in patients with liver disease. Vitamin K deficiency may coexist, so that abnormal clotting factors are produced due to lack of gamma carboxylation. Moreover during liver failure, there is a reduced capacity to clear activated haemostatic proteins and protein inhibitor complexes from the circulation. Usually therapy for coagulation disorders in liver disease is needed only during bleeding or before invasive procedures. When end stage liver disease occurs, liver transplantation is the only treatment available, which can restore normal haemostasis, and correct genetic clotting defects, such as haemophilia or factor V Leiden mutation. During liver transplantation haemorrage may occur due to the pre-existing hypocoagulable state, the collateral circulation caused by portal hypertension and increased fibrinolysis which occurs during this surgery.

Cytokines and toxicity in acetaminophen overdose

Several cytokines have been reported to have hepatoprotective properties in animal models of acetaminophen toxicity. To investigate the relationships of cytokines and toxicity in acetaminophen overdose, blood samples were collected from patients following acute ingestions of acetaminophen. Samples for cytokine analysis were collected at the time of routine clinical monitoring in 111 patients (90 females; mean age 13.6 years). Plasma concentrations of interleukin 6, interleukin 8, interleukin 10, and monocyte chemoattractant protein 1 were analyzed by enzyme-linked immunosorbent assay. Patients were stratified by toxicity severity, defined by the maximal values of hepatic transaminase elevation. Levels of interleukin 6, interleukin 8, and monocyte chemoattractant protein 1 were higher in patients with serum alanine aminotransferase > 1000 IU/L, and monocyte chemoattractant protein 1 had the strongest association with toxicity. Monocyte chemoattractant protein 1 values were higher in patients with greater delays in N-acetylcysteine treatment and in patients with higher values of prothrombin time. Monocyte chemoattractant protein 1 elevation in acetaminophen overdose may represent an innate, immunomodulary response of the liver to earlier events in the toxicity. An understanding of the role of cytokine responses in acetaminophen overdose may be relevant to the future development of new therapies for acetaminophen toxicity.

Selection for acute liver failure: have we got it right?

1. The interplay of four factors determines the outcome in Acute Liver Failure (ALF). Current criteria used for prognosis address each of these factors. a. Hepatic regeneration: Age, poor prognostic etiologies (drug, idiopathic ALF), b. Hepatocellular failure: INR, Bilirubin, c. Encephalopathy and brain edema: Stage III/IV, hyperacute vs acute/subacute, d. Multiorgan failure (MOF): pH. 2. In hyperacute liver failure, exemplified by acetaminophen-induced injury, prognostic criteria have focused on the course of encephalopathy and of multiorgan failure. In non-acetaminophen induced ALF, prognostic criteria reflect a greater role of hepatic regeneration in outcome. 3. Prognostic indices combine features of these four factors. The Kings College criteria (KCC) have been shown to have a better performance than the Clichy criteria. The KCC appear to have a higher specificity than sensitivity for acetaminophen-induced ALF, while its negative predictive value for non-acetaminophen induced ALF is unfortunately low. 4. Newer prognostic markers have been proposed, including serum phosphate and alpha fetoprotein as markers of regeneration and blood lactate, a reflection of MOF and hepatocellular failure. They are likely to complement the KCC rather than replace them. 5. Clinical judgement is still needed to weigh management options in this disease.

Extra-hepatic factor VIII expression in porcine fulminant hepatic failure

In humans, fulminant hepatic failure (FHF) is frequently associated with increased factor VIII (FVIII) levels, despite widespread liver cell death. The mechanisms leading to increased FVIII levels and cellular sites of this enhanced FVIII production are poorly understood. We studied the effect of total hepatectomy in pigs, a large-animal model of FHF, on the expression of plasma and tissue FVIII during 24-hour follow-up. Tissue FVIII expression was determined before and 24 h after hepatectomy, both at the mRNA level and immunohistochemically. The expression of plasma and tissue von Willebrand factor (VWF), the natural stabilizing carrier protein of FVIII, was also measured. Total hepatectomy elicited a gradual and sustained twofold elevation of circulating FVIII, whereas FVIII mRNA levels in various organs did not increase after hepatectomy. The half-life of FVIII increased from 7.7 to 10.3 h and VWF levels were also elevated in anhepatic pigs. The increase in the half-life of FVIII and increased levels of VWF were not sufficient to explain the rise in plasma FVIII levels. At the protein level, prominent changes in the cellular distribution of FVIII were seen in spleen and kidney. These observations suggest that in this model of FHF the lack of hepatic FVIII synthesis is adequately compensated by other organs, notably spleen and kidneys.

Pharmacokinetics and efficacy of oral versus intravenous mixed-micellar phylloquinone (vitamin K1) in severe acute liver disease

BACKGROUND/AIMS

In patients with severe acute liver dysfunction, i.v. phylloquinone (vitamin K1) may be given to exclude vitamin K deficiency, rather than impaired hepatic synthesis of coagulation factors alone, as the cause of the coagulopathy. However, there have been no studies of the pharmacokinetics or efficacy of i.v. or oral K1 in such patients.

METHODS

49 adults with severe acute liver disease were randomised double-blind to a single 10 mg dose of i.v. or oral mixed-micellar K(1), or placebo. Serum levels of phylloquinone and undercarboxylated prothrombin (PIVKA-II) were assessed before and after treatment.

RESULTS

At admission, 13 patients (27%) had either low serum K1 levels or elevated PIVKA-II concentrations, indicative of subclinical vitamin K deficiency. In the 16 patients who received i.v. K1, there was one (6%) treatment failure (K1 rise <10 ng/ml above baseline), compared with 12 of the 15 (80%) who received oral K1 (P<0.0001). One patient in the placebo group developed overt vitamin K deficiency.

CONCLUSIONS

A minority of patients with severe acute liver dysfunction have subclinical vitamin K deficiency at the time of presentation, which is corrected by a single dose of i.v. K1. The intestinal absorption of mixed-micellar K1 is unreliable in adults with severe acute liver dysfunction.

Platelet hyperfunction as risk factor for chronic and acute coronary events

Indians have a very high incidence of vascular complications, such as hypertension, atherosclerosis, coronary artery disease (CAD), and stroke, compared to any other ethnic group in the world. They also have a very high incidence of multiple metabolic diseases, including type 2 diabetes. Elevated levels of known risk factors in this population for CAD does not explain adequately the significant increase in the vascular disease burden in this population. There is some speculation that genetic predisposal of this population may account for this increased incidence in vascular diseases. Environmental toxicants may also contribute significantly to the acceleration of these complex risk promoters. Functional and structural changes in the arterial wall precede the development of clinical complications such as endothelial dysfunction, hypertension, atherosclerosis, hyperfunction of platelets, and coagulation cascade. Vascular dysfunction, therefore, is the major contributor for the pathogenesis of hypertension, atherogenesis, thrombosis, and stroke. Alterations in the balance between platelet-associated vasoconstrictors and endothelial-derived vasodilators result in the vascular dysfunction. Blood platelets play a very important role in the pathogenesis of hypertension, atherogenesis, thrombosis, and stroke. These cells interact with a variety of agonists. Such interactions stimulate specific receptors and lead to the activation of intracellular effector enzymes. Ionized calcium is the primary bioregulator and a variety of signaling mechanisms modulate the cellular physiology and functions. Activated platelets promote the formation of thrombin and initiate coagulation cascade. They also interact with other circulating blood cells and facilitate inflammatory response. Little is known about the effect of environmental toxicants on vascular physiology and pathology. This is true also on their effect on the circulating blood cells. There is some evidence that oxidative stress as well as proinflammatory compounds play a role in vascular biology. In this presentation an attempt will be made to briefly review the known risk factors for CAD; the role of toxicants, eicosanoids, and inflammatory mediators on vascular biology specifically; and the role of platelets and platelet-derived biomolecules on hypertension, atherogenesis, thrombosis, and intercellular communications. Alterations in signaling pathways by environmental toxicants may increase the risk for hypertension, atherosclerosis, thrombosis, and stroke.

Endogenous heparin-like activity detected by anti-Xa assay in infected cirrhotic and non-cirrhotic patients

BACKGROUND

Bacterial infections have been proposed as a trigger for portal hypertensive bleeding in cirrhotic patients. Endogenous low molecular weight heparinoids have been previously detected in vitro by heparinase-modified thromboelastography, but it is not known what type of heparinoids they are. The aim of this study was to assay anti-Xa concentrations to detect heparin activity in infected cirrhotics in vivo.

METHODS

We evaluated 30 cirrhotic patients (15 with bacterial infection, 15 not infected) and 9 non-cirrhotic patients with bacterial infection. The anti-Xa assay was performed at the start of infection in all patients and after resolution of infection in 8 cirrhotics (5 to 10 days after starting antibiotics); thromboelastography (native and heparinase I-modified TEG) was performed in a subgroup of 11 cirrhotic patients with infection, 8 cirrhotics without infection and 8 non-cirrhotics with infection.

RESULTS

Anti-Xa activity was detected in 9 of the 15 infected cirrhotics (60%) and only in 1 of 15 non-infected cirrhotics (6.7%) (P < 0.01). In the infected cirrhotic patients, a heparinase effect was shown in the heparinase I-modified TEG: k time (P < 0.01), alpha-angle (P < 0.01) and r time (P = 0.05), with no effect in the non-infected cirrhotics. Four of 9 (44%) infected non-cirrhotics were positive with the anti-Xa assay.

CONCLUSION

In cirrhotic patients, bacterial infections modify haemostasis by producing endogenous heparin-like substances which can inhibit the activated clotting factor X (factor Xa). In infected non-cirrhotics, anti-Xa activity can also be found.