Coagulation factor XI in cirrhosis does not predict thrombo-hemorrhagic complications and hepatic decompensation.

INTRODUCTION: Factor XI (FXI) is associated with thrombosis in patients without liver disease, but it alterations and prognostic value in cirrhosis are uncertain. PATIENTS AND METHODS: We studied a prospective cohort of cirrhosis patients determining FXI and its association with portal vein thrombosis (PVT), bleeding, and hepatic decompensation/ACLF during 1-year follow-up. Odds ratios (OR) and 95 % CIs were calculated using logistic regression. RESULTS: We included 183 patients (Child-Pugh [CP] A/B/C 57/59/57). FXI was reduced in cirrhosis, decreasing with CP stage (78 % [66-94] vs. 58 % [44-78] vs. 41 % [30-52] in CP A, B, and C, respectively; p < 0.001). FXI was correlated with MELD score (rho: -0.6, p < 0.001), INR (rho: -0.6, p < 0.001), and platelet count (rho: 0.4, p < 0.001). Sixteen patients (8.7 %) experienced PVT, which only predictor was baseline platelet count (OR: 0.94; CI95 %: 0.91-0.97, p < 0.001). Bleeding occurred in 7 patients (3.8 %). Cirrhosis severity, platelet count, fibrinogen, and FXI (60% vs. 78 %; p = 0.2) were comparable between bleeding and non-bleeding individuals. Finally, no association was found between FXI and hepatic decompensation/ACLF, which were predicted by lower albumin and platelet count, respectively. CONCLUSION: FXI seems not to be responsible for thrombosis and cirrhosis progression. The lack of association between low FXI and bleeding events, however, indirectly opens to future studies evaluating FXI inhibitors in cirrhosis.

Cryptogenic ischemic stroke in cardiac transthyretin amyloidosis and sinus rhythm: a case report.

Cardiac amyloidosis is a group of diseases characterized by the deposition of amyloid fibers in cardiac tissue. Two forms are mainly reported: light chain (AL) and transthyretin (ATTR) amyloidosis. Among the complications of transthyretin amyloidosis there are thrombotic events and, to a lesser extent, hemorrhagic events. The latter are likely caused by perivascular amyloid deposition resulting in capillary fragility, in addition to INR lability during anticoagulant therapy. The onset of thrombotic events may be caused by the high prevalence of atrial fibrillation (AF), mechanical cardiac dysfunction and atrial myopathy observed in patients with transthyretin amyloidosis. It remains unclear why thromboembolic events occur even in patients with sinus rhythm or adequate anticoagulation, though a hypercoagulable state or underlying inflammation may be involved. We report a case of cryptogenic ischemic stroke in an 86-year-old woman with transthyretin amyloidosis and sinus rhythm. Traditional coagulation tests, whole blood rotational thromboelastometry and impedance aggregometry did not show a hypercoagulable state. The thrombin generation assay did not reveal a prothrombotic state. However, the study of extracellular vesicles highlighted underlying immune-mediated endothelial damage likely responsible for the thrombotic diathesis. It could be hypothesized that inflammation plays a role in the hypercoagulability of patients with transthyretin amyloidosis. Larger prospective studies are needed to validate our hypothesis.

In vitro and ex vivo rescue of a nonsense mutation responsible for severe coagulation factor V deficiency.

BACKGROUND: Coagulation factor V (FV) deficiency is a rare bleeding disorder that is usually managed with fresh-frozen plasma. Patients with nonsense mutations may respond to treatment with readthrough agents. OBJECTIVES: To investigate whether the F5 p.Arg1161Ter mutation, causing severe FV deficiency in several patients, would be amenable to readthrough therapy. METHODS: F5 mRNA and protein expression were evaluated in a F5 p.Arg1161Ter-homozygous patient. Five readthrough agents with different mechanisms of action, i.e. G418, ELX-02, PTC-124, 2,6-diaminopurine (2,6-DAP), and Amlexanox, were tested in in vitro and ex vivo models of the mutation. RESULTS: The F5 p.Arg1161Ter-homozygous patient showed residual F5 mRNA and functional platelet FV, indicating detectable levels of natural readthrough. COS-1 cells transfected with the FV-Arg1161Ter cDNA expressed 0.7% FV activity compared to wild-type. Treatment with 0-500 µM G418, ELX-02, and 2,6-DAP dose-dependently increased FV activity up to 7.0-fold, 3.1-fold, and 10.8-fold, respectively, whereas PTC-124 and Amlexanox (alone or in combination) were ineffective. These findings were confirmed by thrombin generation assays in FV-depleted plasma reconstituted with conditioned media of treated cells. All compounds except ELX-02 showed some degree of cytotoxicity. Ex vivo differentiated megakaryocytes of the F5 p.Arg1161Ter-homozygous patient, which were negative at FV immunostaining, turned positive after treatment with all 5 readthrough agents. Notably, they were also able to internalize mutant FV rescued with G418 or 2,6-DAP, which would be required to maintain the crucial platelet FV pool in vivo. CONCLUSION: These findings provide in vitro and ex vivo proof-of-principle for readthrough-mediated rescue of the F5 p.Arg1161Ter mutation.

Whole blood thrombin generation shows a significant hypocoagulable state in patients with decompensated cirrhosis.

BACKGROUND: Patients with cirrhosis have a normal to increased thrombin generation (TG) capacity in platelet-poor plasma (PPP). By reflecting the contribution of all circulating blood cells, whole blood (WB) TG may allow a more physiological assessment of coagulation. OBJECTIVES: We compared WB-TG vs PPP-TG in patients with cirrhosis. METHODS: Assessment of coagulation included routine tests, factor VIII, natural anticoagulants, PPP-TG, and WB-TG. TG assays were performed with and without thrombomodulin. Twenty-five healthy subjects were included as controls. RESULTS: We included 108 patients (Child-Pugh A/B/C, 44/24/40). Compared with controls, patients had significantly lower platelet count, longer international normalized ratio, higher FVIII, and lower levels of protein C/S and antithrombin. Regarding thrombomodulin-modified TG assays, in compensated cirrhosis, both PPP-TG and WB-TG indicated an increased TG capacity, as reflected by an endogenous thrombin potential (ETP) significantly higher than controls. In contrast, in decompensated cirrhosis, PPP-TG indicated a hypercoagulable state with increased ETP, higher peak height, and shorter time-to-peak than controls, whereas WB-TG revealed a progressive impairment of TG kinetics and total capacity, ultimately resulting in a profound hypocoagulable state in patients with Child-Pugh C cirrhosis (ie, significant prolongation of lag time and time-to-peak with reduction of both ETP and peak height). In decompensated patients, bacterial infections and severity of anemia were associated with a further reduction of both ETP and peak height. CONCLUSION: Compensated cirrhosis is associated with an increased TG capacity. In decompensated cirrhosis, contrary to PPP-TG, which indicates hypercoagulability, WB-TG shows a significant hypocoagulable state. The clinical value of these findings deserves further investigation.

Crucial roles of red blood cells and platelets in whole blood thrombin generation.

Red blood cells (RBCs) and platelets contribute to the coagulation capacity in bleeding and thrombotic disorders. The thrombin generation (TG) process is considered to reflect the interactions between plasma coagulation and the various blood cells. Using a new high-throughput method capturing the complete TG curve, we were able to compare TG in whole blood and autologous platelet-rich and platelet-poor plasma to redefine the blood cell contributions to the clotting process. We report a faster and initially higher generation of thrombin and shorter coagulation time in whole blood than in platelet-rich plasma upon low concentrations of coagulant triggers, including tissue factor, Russell viper venom factor X, factor Xa, factor XIa, and thrombin. The TG was accelerated with increased hematocrit and delayed after prior treatment of RBC with phosphatidylserine-blocking annexin A5. RBC treatment with ionomycin increased phosphatidylserine exposure, confirmed by flow cytometry, and increased the TG process. In reconstituted blood samples, the prior selective blockage of phosphatidylserine on RBC with annexin A5 enhanced glycoprotein VI-induced platelet procoagulant activity. For patients with anemia or erythrocytosis, cluster analysis revealed high or low whole-blood TG profiles in specific cases of anemia. The TG profiles lowered upon annexin A5 addition in the presence of RBCs and thus were determined by the extent of phosphatidylserine exposure of blood cells. Profiles for patients with polycythemia vera undergoing treatment were similar to that of control subjects. We concluded that RBC and platelets, in a phosphatidylserine-dependent way, contribute to the TG process. Determination of the whole-blood hypo- or hyper-coagulant activity may help to characterize a bleeding or thrombosis risk.

Severity of systemic inflammation is the main predictor of ACLF and bleeding in individuals with acutely decompensated cirrhosis.

BACKGROUND & AIMS: Hypercoagulability and hypofibrinolysis in acutely decompensated cirrhosis (AD) may be implicated in disease progression and haemostatic complications. We conducted a prospective study to: (1) characterise haemostatic alterations in AD; (2) evaluate whether such alterations can predict acute-on-chronic liver failure (ACLF) and bleeding/thrombosis. METHODS: Hospitalised individuals with AD were prospectively recruited and underwent an extensive haemostatic profiling including coagulation factors, thrombomodulin-modified thrombin generation assay with evaluation of endogenous thrombin potential (ETP; marker for plasmatic hypercoagulability), fibrinolytic factors, and plasmin-antiplasmin complex (fibrinolysis activation marker). Inflammation severity was assessed by C-reactive protein (CRP). In part 1 of the study, we compared haemostasis in AD vs. controls (stable decompensated and compensated cirrhosis). In part 2 of the study, we prospectively followed individuals with AD for 1 year and investigated predictors of ACLF and bleeding/thrombosis. RESULTS: A total of 169 individuals with AD were recruited (median model for end-stage liver disease score 20; CLIF-C AD 54). Compared with controls, AD was associated with more pronounced hypercoagulability (ETP: 871 vs. 750 vs. 605 nmol/L per min; p <0.0001), without differences in fibrinolysis activation. During follow-up, 55 individuals developed ACLF. CLIF-C AD, CRP, and Child-Pugh were independently associated with ACLF. A predictive model combining these variables (Padua model) accurately identified individuals at higher risk of ACLF (AUROC 0.857; 95% CI 0.798-0.915; sensitivity 74.5%, specificity 83.3%). Notably, CRP and progression to ACLF, but not baseline coagulopathy, were associated with bleeding (n = 11); CRP and antifibrinolytic factor PAI-1 >50 ng/ml were associated with thrombosis (n = 14). The prognostic value of the Padua model was validated in an independent, bicentric European cohort (N = 301). CONCLUSIONS: Inflammation severity, and not coagulopathy, is the most important predictor of ACLF and bleeding in AD. The Padua model can be used to identify individuals with AD at risk of ACLF. IMPACT AND IMPLICATIONS: A better understanding of haemostasis in individuals with acutely decompensated cirrhosis may help to identify those at higher risk of progression and complications. In this prospective study, we found no significant association between alterations of haemostasis and cirrhosis progression, indicating that the assessment of haemostatic alterations is not useful to identify those at risk. However, we found that C-reactive protein (a simple blood test that reflects severity of inflammation) and severity of chronic liver disease itself (as assessed by specific scores) were associated with cirrhosis progression and development of bleeding complications. Therefore, we developed a simple predictive model - based on C-reactive protein and liver disease scores - that, if validated by independent studies, could be used in clinical practice to assist physicians in identifying individuals with decompensated cirrhosis at higher risk of disease progression and death (i.e. in whom to consider an expedited evaluation for liver transplantation).

Global hemostatic profiling in patients with decompensated cirrhosis and bacterial infections.

Background & Aims: Bacterial infections in cirrhosis are associated with increased bleeding risk. To assess the factors responsible for bleeding tendency in patients with bacterial infections, we conducted a prospective study comparing all 3 aspects of hemostasis (platelets, coagulation, and fibrinolysis) in hospitalized patients with decompensated cirrhosis with vs. without bacterial infections. Methods: Primary hemostasis assessment included whole blood platelet aggregation and von Willebrand factor (VWF). Coagulation assessment included procoagulant factors (fibrinogen, factor II, V, VII, VIII, IX, X, XI, XII, XIII), natural anticoagulants (protein C, protein S, antithrombin) and thrombomodulin-modified thrombin generation test. Fibrinolysis assessment included fibrinolytic factors (plasminogen, t-PA, PAI-1, α2-AP, TAFIa/ai) and plasmin-antiplasmin complex (PAP). Results: Eighty patients with decompensated cirrhosis were included (40 with and 40 without bacterial infections). Severity of cirrhosis and platelet count were comparable between groups. At baseline, patients with cirrhosis and bacterial infections had significantly lower whole blood platelet aggregation, without significant differences in VWF. Regarding coagulation, bacterial infections were associated with reduced procoagulant factors VII and XII, and a significant reduction of all natural anticoagulants. However, thrombomodulin-modified thrombin generation was comparable between the study groups. Finally, although mixed potentially hypo-fibrinolytic (lower plasminogen) and hyper-fibrinolytic (higher t-PA) changes were present in bacterial infections, a comparable level of PAP was detected in both groups. Upon resolution of infection (n = 29/40), platelet aggregation further deteriorated whereas coagulation and fibrinolysis factors returned to levels observed in patients without bacterial infections. Conclusion: In hospitalized patients with decompensated cirrhosis, bacterial infections are associated with reduced whole blood platelet aggregation and a significant decrease of all natural anticoagulants, which may unbalance hemostasis and potentially increase the risk of both bleeding and thrombosis. Lay summary: Bacterial infections are a common issue in hospitalized patients with decompensated cirrhosis (i.e. patients hospitalized due to severe complications of advanced chronic liver disease). Patients with decompensated cirrhosis who acquire infections may be at increased risk of bleeding complications following invasive procedures (that is a procedure in which the body is penetrated or entered, for instance by a needle or a tube). As bleeding complications in decompensated cirrhosis are associated with a high risk of further decompensation and death, there is an urgent need to understand the factors responsible for such increased bleeding tendency. Herein, we investigated the alterations of hemostasis (that is the physiological process responsible for clot formation and stability) in patients with decompensated cirrhosis and bacterial infections. We found that development of bacterial infections in these patients is associated with alterations of hemostasis (particularly of platelets and clotting cascade) that may increase the risk of both bleeding and thrombotic complications.

Increased platelet aggregation in patients with decompensated cirrhosis indicates higher risk of further decompensation and death.

BACKGROUND & AIMS: Studies on platelet aggregation in cirrhosis are controversial because interpretation of platelet function is challenged by thrombocytopenia. We conducted a prospective study to investigate whole blood platelet aggregation in cirrhosis and its association with liver-related outcomes. METHODS: Platelet aggregation was assessed by whole blood aggregometry (Multiplate®). To overcome the influence of platelet count and compare cirrhosis with thrombocytopenia vs. controls with normal platelet count, we calculated a ratio between platelet aggregation and platelet count (PLT ratio). Then, we prospectively followed patients with cirrhosis and ascertained predictors of decompensation, transplantation, and death. RESULTS: Two-hundred and three patients with cirrhosis were prospectively recruited (77% decompensated). PLT ratio was significantly higher in cirrhosis than in those with chronic hepatitis and healthy individuals (0.44 vs. 0.25 and 0.26, respectively; p <0.0001). In cirrhosis, the ratio increased with disease severity (Child-Pugh class C>B>A) and was particularly elevated in decompensated patients with severe thrombocytopenia. Among decompensated patients, 65 had further decompensation, underwent transplantation, or died during a 6-month follow-up. On multivariate analysis, PLT ratio (odds ratio 1.87; 95% CI 1.23-2.84; p = 0.003) and MELD score (odds ratio 1.05; 95% CI 1.01-1.08; p = 0.01) were independently associated with outcome. The relative risk of events was 7.5-fold higher in patients with PLT ratio >0.75 vs. patients with PLT ratio <0.25 (95% CI 2.5-21.9; p = 0.003). The increased PLT ratio, its discriminative ability for composite outcome, and the prognostic value of PLT ratio >0.75 were confirmed in an independent cohort of hospitalized patients with decompensated cirrhosis (n = 41). CONCLUSIONS: Patients with cirrhosis, particularly when decompensated, exhibit significantly increased whole blood platelet aggregation. Decompensated patients with a PLT ratio >0.75 have a >80% probability of further decompensation, transplantation, or liver-related death within 6 months. LAY SUMMARY: In patients with cirrhosis, previous studies have suggested that platelets (i.e. circulating blood cells that help form clots to stop bleeding) are dysfunctional. In particular, these studies suggested that platelet aggregation (the process by which platelets adhere to each other to form clots) is reduced. Since platelet aggregation is important for clot formation, it has been hypothesized that alterations of platelet aggregation may be responsible for the increased risk of bleeding observed in patients with cirrhosis. Our study demonstrates: i) that platelet aggregation in patients with cirrhosis is higher than in healthy individuals; ii) that platelet aggregation in patients with decompensated cirrhosis (i.e. those who have already experienced some complications of cirrhosis) is particularly elevated and associated with risk of further complications and death.

Protein C or Protein S deficiency associates with paradoxically impaired platelet-dependent thrombus and fibrin formation under flow.

Background: Low plasma levels of protein C or protein S are associated with venous thromboembolism rather than myocardial infarction. The high coagulant activity in patients with thrombophilia with a (familial) defect in protein C or S is explained by defective protein C activation, involving thrombomodulin and protein S. This causes increased plasmatic thrombin generation. Objective: Assess the role of platelets in the thrombus- and fibrin-forming potential in patients with familial protein C or protein S deficiency under high-shear flow conditions. Patients/Methods: Whole blood from 23 patients and 15 control subjects was perfused over six glycoprotein VI-dependent microspot surfaces. By real-time multicolor microscopic imaging, kinetics of platelet thrombus and fibrin formation were characterized in 49 parameters. Results and Conclusion: Whole-blood flow perfusion over collagen, collagen-like peptide, and fibrin surfaces with low or high GPVI dependency indicated an unexpected impairment of platelet activation, thrombus phenotype, and fibrin formation but unchanged platelet adhesion, observed in patients with protein C deficiency and to a lesser extent protein S deficiency, when compared to controls. The defect extended from diminished phosphatidylserine exposure and thrombus contraction to delayed and suppressed fibrin formation. The mechanism was thrombomodulin independent, and may involve negative platelet priming by plasma components.

Assessing Clinically Meaningful Hypercoagulability after COVID-19 Vaccination: A Longitudinal Study.

A large number of daily requests to exclude possible prothrombotic risk factors for coronavirus disease 2019 (COVID-19) vaccines were received. Our aim was to longitudinally evaluate coagulation profiles in a series of healthy subjects who received COVID-19 vaccination and assess hypercoagulability thereafter. Volunteers awaiting a first or second dose of either the ChAdOx1 or BNT162b2 vaccine were enrolled. Venous samples were obtained at baseline (before the vaccine) and longitudinally 3 ± 2 days (T1) and 10 ± 2 days after the vaccine (T2). Global coagulation monitoring was assessed via platelet count, whole blood thromboelastometry and impedance aggregometry, plasma thrombin generation, and anti-platelet factor 4 (PF4)/heparin immunoglobulin G antibodies. One hundred and twenty-two subjects were enrolled (61 [50%] ChAdOx1 and 61 BNT162b2). The ChAdOx1 cohort showed a slight but transient increase in thrombin generation (mainly endogenous thrombin potential [ETP] with thrombomodulin and ETP ratio) at T1, which promptly decreased at T2. In addition, the second dose of either vaccine was associated with increased thrombin peak, ETP with thrombomodulin, and ETP ratio. At baseline, 3.2% of the ChAdOx1 cohort and 1.6% BNT162b2 cohort were positive for PF4/heparin antibodies with a stable titer through T1 and T2. No relevant differences were detected in platelet count and aggregation, or thromboelastometry parameters. No thrombotic or hemorrhagic events occurred. We can confirm that no clinically meaningful hypercoagulability occurred after either vaccine, albeit keeping in mind that thrombin generation may increase in the first days after the second dose of either vaccine and after the first dose of the ChAdOx1 vaccine.

More Pronounced Hypercoagulable State and Hypofibrinolysis in Patients With Cirrhosis With Versus Without HCC.

In patients with cirrhosis, particularly those with hepatocellular carcinoma (HCC), hypercoagulability may be associated with purported increased risks of portal vein thrombosis and cirrhosis progression. In this study, we extensively investigated hemostatic alterations potentially responsible for the thrombotic tendency in HCC, and evaluated whether such alterations were predictive of hepatic decompensation. Patients with cirrhosis at all stages were prospectively recruited and underwent an extensive hemostatic assessment, including all procoagulant factors and inhibitors, thrombin generation with and without thrombomodulin (TG), profibrinolytic and antifibrinolytic factors, and plasmin-antiplasmin complex. In study part 1 (case control), we compared alterations of coagulation and fibrinolysis in patients with cirrhosis with versus without HCC. In study part 2 (prospective), the subgroup of patients with decompensated cirrhosis was followed for development of further decompensation, and predictors of outcome were assessed by multivariate analysis. One-hundred patients were recruited (50 each with and without HCC). Severity of cirrhosis was comparable between groups. Median HCC volume was 9 cm3 (range: 5-16). Compared with controls, patients with HCC demonstrated a significantly more prothrombotic hemostatic profile due to increased TG and reduced activation of fibrinolysis, independent of cirrhosis stage. During a median follow-up of 175 days, 20 patients with decompensated cirrhosis developed further episodes of decompensation that were predicted by low FVII and high plasminogen activator inhibitor-1 levels, independent of Model for End-Stage Liver Disease score. Conclusion: Patients with cirrhosis with HCC have profound hyper-coagulable changes that can account for their increased thrombotic tendency. In contrast, hypercoagulability in patients with decompensated cirrhosis is more likely a consequence of chronic liver disease rather than a driver for cirrhosis progression.

Coagulopathy is not predictive of bleeding in patients with acute decompensation of cirrhosis and acute-on-chronic liver failure.

BACKGROUND & AIMS: Understanding factors responsible for the increased bleeding tendency in acute-on-chronic liver failure (ACLF) would improve the management of these complications. We investigated coagulation alterations in ACLF and assessed whether they were predictive of bleeding. METHODS: Cirrhosis patients with ACLF (cases) and acute decompensation (AD, controls) were prospectively recruited and underwent an extensive haemostatic assessment including standard tests, pro and anticoagulant factors, thrombomodulin-modified thrombin generation (TG) and thromboelastometry (ROTEM® ). In study part 1 (case-control), we compared coagulation in ACLF vs AD. In study part 2 (prospective), all patients were followed for bleeding, and predictors of outcome were assessed. RESULTS: Ninety-one patients were included (51 with ACLF, 40 with AD). Infections and ascites/renal dysfunction were the most common precipitating and decompensating events. Platelet count was lower while INR and activated partial thrombin time were longer in ACLF cohort vs AD. Regarding clotting factors, fibrinogen and factor VIII were comparable between groups while protein C and antithrombin were significantly reduced in ACLF. Endogenous thrombin potential by TG was comparable between groups. Clotting formation time and clot stability by ROTEM® were significantly lower in ACLF, indicative of a more hypocoagulable state. No haemostasis alteration could discriminate between patients who had bleeding complications during hospitalization and those who did not. CONCLUSION: We found coagulation changes in ACLF to largely overlap with that of AD and evidence of preserved coagulation capacity in both groups. ROTEM alterations were indicative of a more pronounced hypocoagulable state in ACLF; however, no correlation was found between such alterations and bleeding.

Absence of hypercoagulability after nCoV-19 vaccination: An observational pilot study.

BACKGROUND: It is still unknown whether COVID-19 vaccines induce a prothrombotic state or increase the hypercoagulable condition in subjects with a predisposition to thrombosis. OBJECTIVES: We evaluated the coagulation profile in a series of healthy subjects who received the first dose of the BNT162b2 or the ChAdOx1 vaccines and assessed whether hypercoagulability developed. PATIENTS/METHODS: Volunteers among the staff of the University of Padua or health care professionals in the Padua University Hospital who had received either the ChAdOx1 or BNT162b2 vaccine in the previous 10 ± 2 days were eligible. A cohort of unvaccinated volunteers among family members of the University staff acted as control group. Global coagulation monitoring was assessed by whole blood rotational thromboelastometry, whole blood impedance aggregometry and thrombin generation. Platelet count was also obtained. RESULTS: One hundred and ninety subjects were enrolled: 101 (53.2%) received the ChAdOx1 vaccine and 89 (46.8%) the BNT162b2 vaccine. Twenty-eight non-vaccinated subjects acted as controls. Thromboelastometry parameters were all comparable among groups. Thrombin receptor activating peptide (TRAP)-, ADP- and ASPI-induced platelet aggregation were similar among groups, as well as platelet count. Endogenous thrombin potential (ETP) was comparable among groups. The results were confirmed after controlling for age, gender and hormonal. Considering women taking combined oral contraceptives or thrombophilia carriers, no differences were detected in thromboelastometry or thrombin generation parameters between subjects who received ChAdOx1 vs. BNT162b2 vaccines. CONCLUSIONS: No significant activation of fibrinogen-driven coagulation, plasma thrombin generation or clinically meaningful platelet aggregation after ChAdOx1 or BNT162b2 vaccination was observed.

Influence of Hepatocellular Carcinoma on Platelet Aggregation in Cirrhosis.

Hyper-functional platelets are being proposed as a potential therapeutic target in multiple cancers. Whether this can be considered in patients with cirrhosis and hepatocellular carcinoma (HCC) is unknown as their platelet function has not yet been investigated. We evaluated platelet function in cirrhosis patients with HCC. Patients with cirrhosis with and without HCC were prospectively recruited. Platelet aggregation, a marker of platelet function, was assessed by impedance aggregometry with adenosine diphosphate (ADP), arachidonic acid (ASPI), and thrombin (TRAP) stimulation. Plasmatic levels of Von Willebrand factor antigen (VWF) were also determined. One-hundred patients were recruited (50 cirrhotics with and 50 without HCC). Cirrhosis severity by Child class and platelet count were comparable between cirrhotics with and without HCC. Cirrhotics with HCC had higher ADP- (45 vs. 28; p < 0.001), ASPI- (47 vs. 28; p < 0.001), and TRAP- (85 vs. 75; p = 0.01) induced platelet aggregation than cirrhotics without HCC, all indicative of platelet hyper-function. The relatively increased platelet aggregation in patients with HCC was confirmed after adjusting the analysis for platelet count/severity of thrombocytopenia. Levels of VWF were higher in patients with vs. without HCC (348 vs. 267; p = 0.006), particularly in compensated cirrhosis. In patients with cirrhosis, HCC is associated with increased platelet aggregation and higher VWF. The clinical implications of these findings deserve further investigation.

Thrombin generation in patients with COVID-19 with and without thromboprophylaxis.

OBJECTIVES: Thrombin generation (TG) with and without thrombomodulin (TM) was evaluated in COVID-19 patients with different disease severity and thromboprophylaxis regimen, in order to understand the prothrombotic profile. METHODS: We enrolled consecutive patients with confirmed diagnosis of COVID-19 admitted to Medical Departments (MD) or Intensive Care Units (ICU), and 54 healthy controls. RESULTS: Eighty-nine patients were included (mean age 60.4±16.1 years, 68.5% male); 33.7% admitted to ICU. Twenty-four patients (26.9%) were enrolled before thromboprophylaxis administration; 45 patients (50.6%) received standard and 20 (22.5%) intermediate sub-therapeutic dose thromboprophylaxis. Overall, patients with COVID-19 showed a TG profile comparable to that of healthy subjects (i.e. comparable peak height, endogenous thrombin potential [ETP] with and without TM). The only exception was lag time and time to peak, prolonged in COVID-19 patients vs. controls. MD patients showed a similar TG profile to healthy controls, and ICU patients showed significantly decrease ETP (p=0.030) compared to MD. As for thromboprophylaxis, TG profile was significantly increased in COVID-19 patients without thromboprophylaxis vs. controls and vs. those with thromboprophylaxis. In this latter group, ETP inhibition was significantly decreased (p=0.0003) and positively correlated with anti-Xa activity (r=0.49, p=0.0017). However, patients with thromboprophylaxis had similar TG profile vs. controls. Intermediate dose thromboprophylaxis more effectively inhibited TG in severe COVID-19 patients by increasing ETP inhibition via ETP with TM reduction vs. standard dose. CONCLUSIONS: COVID-19 patients showed increased TG at diagnosis. Standard thromboprophylaxis reduced TG to levels of healthy controls. Intermediate sub-therapeutic thromboprophylaxis more effectively inhibited TG by decreasing ETP with TM.

Acute kidney injury is associated with increased levels of circulating microvesicles in patients with decompensated cirrhosis.

BACKGROUND: Microvesicles (MVs) play a role in inflammation, coagulation, and vascular homeostasis in liver disease. AIM: To characterize circulating plasma MVs profile in patients with decompensated cirrhosis and acute kidney injury (AKI). METHODS: We measured the levels of total, endothelial, platelet, tissue factor (TF)+, leukocyte and hepatocyte MVs by new generation flow-cytometry in a prospective cohort of patients with decompensated cirrhosis with and without AKI. RESULTS: Eighty patients with decompensated cirrhosis were recruited (40 each with and without AKI). Patients with cirrhosis with AKI had significantly higher calcein+ (total), endothelial, and platelet-MVs. Conversely, TF+, leukocyte, and hepatocyte-MVs were comparable between groups. Resolution of AKI was associated with significantly decreased total and endothelial-MVs that became comparable with those in patients without AKI. Platelet MVs significantly decreased but remained higher compared to patients without AKI. TF+MVs significantly decreased and became lower than patients without AKI. Leukocyte and hepatocyte-MVs remained unchanged. Creatinine (OR 4.3 [95%CI 1.8-10.7]), MELD (OR 1.13 [95%CI 1.02-1.27]), any bleeding (OR 9.07 [95%CI 2.02-40.6]), and hepatocyte-MVs (OR 1.04 [95%CI 1.02-1.07]) were independently associated with 30-day mortality. CONCLUSION: AKI worsened vascular and cellular homeostasis in patients with cirrhosis, particularly by inducing endothelial dysfunction and platelet activation. AKI did not worsen systemic inflammation and hepatocytes activation.

Longitudinal Trend of Plasma Concentrations of Extracellular Vesicles in Patients Hospitalized for COVID-19.

Plasma concentrations of extracellular vesicles (EVs) originating from cells involved in COVID-19-associated coagulopathy (CAC), their longitudinal trend and association with clinical outcomes were evaluated. Blood samples of consecutive COVID-19 patients admitted to a medical Unit were longitudinally collected within 48 h of admission, at discharge and 30 days post-discharge. EVs were analyzed using high sensitivity flow cytometry and phospholipid-dependent clotting time (PPL). The following EVs were measured: endothelium-, platelet-, leukocyte-derived, bearing tissue factor (TF)+, angiotensin-converting enzyme (ACE2)+, platelet-derived growth factor receptor-ß (PDGF-ß)+ and SARS-CoV-2-nucleoprotein (NP)+. 91 patients were recruited for baseline EV analysis (mean age 67 ± 14 years, 50.5% male) and 48 underwent the longitudinal evaluation. From baseline to 30-days post-discharge, we observed significantly decreased plasma concentrations of endothelium-derived EVs (E-Selectin+), endothelium-derived bearing TF (E-Selectin+ TF+), endothelium-derived bearing ACE2 (E-Selectin+ACE2+) and leukocyte-EVs bearing TF (CD45+TF+), p < 0.001, p = 0.03, p = 0.001, p = 0.001, respectively. Conversely, platelet-derived (P-Selectin+) and leukocyte-derived EVs (CD45+) increased from baseline to 30-days post-discharge (p = 0.038 and 0.032, respectively). EVs TF+, ACE2+, PDGF-ß+, and SARS-CoV-2-NP+ did not significantly change during the monitoring. PPL increased from baseline to 30-days post-discharge (+ 6.3 s, p = 0.006). P-Selectin + EVs >1,054/µL were associated with thrombosis (p = 0.024), E-Selectin + EVs ≤531/µL with worsening/death (p 0.026) and 30-days P-Selectin+ and CD45 + EVs with persistent symptoms (p < 0.0001). We confirmed increased EVs originating from cells involved in CAC at admission and discharge. EVs derived from activated pericytes and expressing SARS-CoV-2-NP were also detected. 30-days post-discharge, endothelium-EVs decreased, while platelet- and leukocyte-EVs further increased, indicating that cellular activation persists long after the acute phase.