Reduced platelet activation and platelet aggregation in patients with alcoholic liver cirrhosis

Thrombus aspiration is associated with improved platelet inhibition rate following dual antiplatelet therapy in acute myocardial infarction patients

BACKGROUND

It is well-established that thrombus aspiration during primary percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) indicates a higher thrombus burden and necessitates more intensive antithrombotic therapy. The bidirectional association between adverse events in AMI patients and platelet reactivity is typically observed during dual antiplatelet therapy (DAPT).

OBJECTIVE

To investigate platelet reactivity after DAPT in AMI patients with thrombus aspiration performed during PCI.

METHODS

In this retrospective study, we examined 269 consecutive AMI patients who underwent PCI and recorded their demographic, clinical and laboratory data. The platelet reactivity was measured with thromboelastogram (TEM).

RESULTS

Ultimately, 208 patients were included in this study and divided into a Thrombus Aspiration group (N = 97) and a PCI Alone group (N = 111) based on whether thrombus aspiration was performed or not. The adenosine diphosphate (ADP)-induced platelet inhibition rate in the Thrombus Aspiration group was higher than that in the PCI Alone group (P < 0.001). Furthermore, multivariate linear regression analysis revealed that the ADP-induced platelet inhibition rate was independently associated with leukocyte count, thrombus aspiration and the combination of aspirin and ticagrelor as DAPT after adjusting for potential covariates in all AMI patients.

CONCLUSION

In conclusion, clinicians should exercise heightened attention towards the bleeding risk among patients undergoing PCI concomitant with Thrombus Aspiration postoperatively.

Comprehensive investigation of platelet function in patients with cirrhosis

Cirrhosis presents with thrombocytopenia and possibly thrombocytopathy. Previous studies exploring platelet function gave conflicting results and most controversies are explained by the variety of methods employed for investigation. We sought to assess in-vitro the overall platelet function in cirrhosis. We investigated 34 patients by using the following tests. (i)Aggregometry. (ii)Measurement of the content of platelet granules. (iii)Cytometric platelet activation. (iv)Plasmatic markers of in-vivo platelet activation. (v)Platelet procoagulant activity by thrombin generation (TG) in platelet-rich plasma (PRP). TG measured in PRP for patients and controls was similar. Platelets from patients with cirrhosis showed reduction of aggregation and secretion of ATP. Similar results were observed for platelet activation parameters such as P-selectin expression and PAC-1 platelet binding. Plasma levels of βeta-thromboglobulin and soluble P-selectin, were increased in patients-vs-controls. In contrast, there were no patients-vs-controls differences for plasmatic platelet-factor-4. Results are consistent with a state of in-vivo platelet activation and decreased in-vitro aggregation. Since bleeding events following invasive procedures are uncommon in cirrhosis, we speculate that in-vitro aggregometry testing does not reflect the situation occurring in-vivo. Results of the study and pathophysiological considerations support the conclusion that platelet function in cirrhosis as determined by aggregometry, although somewhat impaired, may support the overall hemostatic potential, which is needed for most invasive interventions. These conclusions are in line with the recommendations of international guidelines, warning against indiscriminate use of prophylactic preprocedural administration of platelets before invasive procedures. Decision on platelet support should not be made based on in-vitro laboratory testing for platelet function.

Platelets in Alcohol-Associated Liver Disease: Interaction With Neutrophils

Alcohol-associated liver disease (ALD) is a major contributor to liver-related mortality globally. An increasing body of evidence underscores the pivotal role of platelets throughout the spectrum of liver injury and recovery, offering unique insights into liver homeostasis and pathobiology. Alcoholic-associated steatohepatitis is characterized by the infiltration of hepatic neutrophils. Recent studies have highlighted the extensive distance neutrophils travel through sinusoids to reach the liver injury site, relying on a platelet-paved endothelium for efficient crawling. The adherence of platelets to neutrophils is crucial for accurate migration from circulation to the inflammatory site. A gradual decline in platelet levels leads to diminished neutrophil recruitment. Platelets exhibit the ability to activate neutrophils. Platelet activation is heightened upon the release of platelet granule contents, which synergistically activate neutrophils through their respective receptors. The sequence culminates in the formation of platelet-neutrophil complexes and the release of neutrophil extracellular traps intensifies liver damage, fosters inflammatory immune responses, and triggers hepatotoxic processes. Neutrophil infiltration is a hallmark of alcohol-associated steatohepatitis, and the roles of neutrophils in ALD pathogenesis have been studied extensively, however, the involvement of platelets in ALD has received little attention. The current review consolidates recent findings on the intricate and diverse roles of platelets and neutrophils in liver pathophysiology and in ALD. Potential therapeutic strategies are highlighted, focusing on targeting platelet-neutrophil interactions and activation in ALD. The anticipation is that innovative methods for manipulating platelet and neutrophil functions will open promising avenues for future ALD therapy.

Decreased platelet activation predicts hepatic decompensation and mortality in patients with cirrhosis

BACKGROUND AND AIMS

Patients with cirrhosis show alterations in primary hemostasis, yet prognostic implications of changes in platelet activation remain controversial, and assay validity is often limited by thrombocytopenia. We aimed to study the prognostic role of platelet activation in cirrhosis, focusing on bleeding/thromboembolic events, decompensation, and mortality.

APPROACH AND RESULTS

We prospectively included 107 patients with cirrhosis undergoing a same-day hepatic venous pressure gradient (HVPG) and platelet activation measurement. Platelet activation was assessed using flow cytometry after protease-activated receptor (PAR)-1, PAR-4, or epinephrine stimulation. Over a follow-up of 25.3 (IQR: 15.7-31.2) months, first/further decompensation occurred in 29 patients and 17 died. More pronounced platelet activation was associated with an improved prognosis, even after adjusting for systemic inflammation, HVPG, and disease severity. Specifically, higher PAR-4-inducible platelet activation was independently linked to a lower decompensation risk [adjusted HR per 100 MFI (median fluorescence intensity): 0.95 (95% CI: 0.90-0.99); p =0.036] and higher PAR-1-inducible platelet activation was independently linked to longer survival [adjusted HR per 100 MFI: 0.93 (95% CI: 0.87-0.99); p =0.040]. Thromboembolic events occurred in eight patients (75% nontumoral portal vein thrombosis [PVT]). Higher epinephrine-inducible platelet activation was associated with an increased risk of thrombosis [HR per 10 MFI: 1.07 (95% CI: 1.02-1.12); p =0.007] and PVT [HR per 10 MFI: 1.08 (95% CI: 1.02-1.14); p =0.004]. In contrast, of the 11 major bleedings that occurred, 9 were portal hypertension related, and HVPG thus emerged as the primary risk factor.

CONCLUSIONS

Preserved PAR-1- and PAR-4-inducible platelet activation was linked to a lower risk of decompensation and death. In contrast, higher epinephrine-inducible platelet activation was a risk factor for thromboembolism and PVT.

Platelet Function Decreases with Increasing Severity of Liver Cirrhosis and Portal Hypertension-A Prospective Study

BACKGROUND

 Cirrhotic patients display an increased risk for both bleeding and thrombosis. We investigated platelet activation across Child-Pugh stages (CPSs) and portal hypertension (PH) severity.

MATERIAL AND METHODS

 A total of 110 cirrhotic patients were prospectively included. CPS and hepatic venous pressure gradient (HVPG) were determined. Platelet surface expression of P-selectin and activated glycoprotein (GP) IIb/IIIa were measured by flow cytometry before/after stimulation with protease-activated receptor (PAR)-1 (thrombin receptor activating peptide, TRAP) and PAR-4 (AYPGKF) agonists, epinephrine, and lipopolysaccharide (LPS).

RESULTS

 Platelet count was similar across CPS but lower with increasing PH severity. Expression of P-selectin and activated GPIIb/IIIa in response to TRAP and AYPGKF was significantly reduced in platelets of CPS-B/C versus CPS-A patients (all p < 0.05). Platelet P-selectin expression upon epinephrine and LPS stimulation was reduced in CPS-C patients, while activated GPIIb/IIIa in response to these agonists was lower in CPS-B/C (all p < 0.05). Regarding PH severity, P-selectin and activated GPIIb/IIIa in response to AYPGKF were lower in HVPG ≥20 mmHg patients (both p < 0.001 vs. HVPG < 10 mmHg). Similarly, activated GPIIb/IIIa was lower in HVPG ≥20 mmHg patients after TRAP stimulation (p < 0.01 vs. HVPG < 10 mmHg). The lower platelet surface expression of P-selectin and activated GPIIb/IIIa upon stimulation of thrombin receptors (PAR-1/PAR-4) in CPS-B/C and HVPG ≥20 mmHg patients was paralleled by reduced antithrombin-III levels in those patients (all p < 0.05). Overall, PAR-1- and PAR-4-mediated platelet activation correlated with antithrombin-III levels (p < 0.001).

CONCLUSION

 Platelet responsiveness decreases with increasing severity of liver cirrhosis and PH but is potentially counterbalanced by lower antithrombin-III levels.

The role of platelets in non-alcoholic fatty liver disease: From pathophysiology to therapeutics

Platelets are one of the key mediators in thrombosis as well as in the progression of many diseases. An increase in platelet activation and a decrease in platelet count is associated with a plethora of liver diseases. In non-alcoholic fatty liver disease (NAFLD), platelets are highly activated and participate in the disease progression by enhancing the pro-thrombotic and pro-inflammatory state. Some altered platelet parameters such as mean platelet volume, plateletcrits, and platelet distribution width, aspartate transaminase to platelet ratio index, liver stiffness to platelet ratio and red cell distribution width to platelet ratio were found to be associated with NAFLD disease. Further, platelet contributes to the progression of cardiovascular complications in NAFLD is gaining the researcher's attention. An elevated mean platelet volume is known to enhance the risk of stroke, atherosclerosis, thrombosis, and myocardial infarction in NAFLD. Evidence also suggested that modulation in platelet function using aspirin, ticlopidine, and cilostazol help in controlling the NAFLD progression. Future research should focus on antiplatelet therapy as a treatment strategy that can control platelet activation in NAFLD as well as its cardiovascular risk. In the present review, we have detailed the role of platelets in NAFLD and its cardiovascular complications. We further aimed to highlight the growing need for antiplatelet therapy in NAFLD.

Antithrombin III activity is associated with prognosis, infection, and inflammation in patients with hepatitis B virus-related acute-on-chronic liver failure

OBJECTIVE

Patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) are characterized by severe liver function impairment, coagulation disorder, and multiple organ function impairment. The aim of this study was to explore the predictive value of antithrombin Ⅲ activity to the prognosis of HBV-ACLF patients.

METHODS

A total of 186 HBV-ACLF patients were included in the analysis, and the baseline clinical data of patients were recorded to analyze the risk factors affecting the 30-day survival outcome of patients. Bacterial infection, sepsis, and hepatic encephalopathy were observed in ACLF patients. Antithrombin Ⅲ activity and serum cytokine levels were determined.

RESULTS

The antithrombin Ⅲ activity of ACLF patients in the death group was significantly lower than that in the survival group, and antithrombin Ⅲ activity was independent factors affecting the 30-day outcome. The areas under the receiver operation characteristic (ROC) curve of antithrombin Ⅲ activity to predict the 30-day mortality of ACLF was 0.799. Survival analysis showed that the mortality of patients with antithrombin Ⅲ activity less than 13% was significantly increased. Patients with bacterial infection and sepsis had lower antithrombin Ⅲ activity than those without infection. Antithrombin Ⅲ activity was positively correlated with platelet count, fibrinogen, interferon (IFN)-γ, interleukin (IL)-13, IL-1β, IL-4, IL-6, tumor necrosis factor-α, IL-23, IL-27, and IFN-α, but negatively correlated with C-reactive protein, D dimer, total bilirubin, and creatinine levels.

CONCLUSION

As a natural anticoagulant, antithrombin Ⅲ can be regarded as a marker of inflammation and infection in patients with HBV-ACLF, and as a predictor of survival outcome in patients with ACLF.

Decreased Platelet Aggregation in Patients with Decompensated Liver Cirrhosis and TIPS Implantation

Transjugular intrahepatic portosystemic shunt (TIPS) implantation is an effective treatment of portal hypertension in patients with decompensated liver cirrhosis. However, some patients develop TIPS thrombosis with recurrence of portal hypertension. The role of platelets in TIPS thrombosis and the necessity of antiplatelet therapy is unclear. Therefore, we aimed to study platelet function in patients with liver cirrhosis prior to and after TIPS implantation. Platelet aggregation was tested in peripheral and portal-vein blood patient samples on the day (D) of TIPS implantation (D0), D4 and D30 following the procedure (platelet count above 100 × 103/µL, aspirin starting on D5) using whole-blood impedance aggregometry (WBIA) and light transmission aggregometry (LTA). In addition, surface platelet activation markers (P-selectin, activated GPIIb/IIIa) and platelet-neutrophil complexes (PNCs) were assessed by flow cytometry. Thrombin receptor activating peptide 6 (TRAP-6), adenosine diphosphate (ADP) and arachidonic acid (AA) were used as agonists. Healthy subjects were included as controls. Agonist-induced platelet aggregation was reduced (WBIA: TRAP-6 p < 0.01, ADP p < 0.01, AA p < 0.001; LTA: TRAP-6 p = 0.13, ADP p = 0.05, AA p < 0.01) in patients (D0, n = 13) compared with healthy subjects (n = 9). While surface activation markers at baseline were negligibly low, the percentage of PNCs was higher in patients than in controls (p < 0.05). ADP-induced P-selectin expression was increased (p < 0.001), whereas TRAP-6-induced GPIIb/IIIa activation was impaired (p < 0.001) in patients versus controls. PNC formation in response to agonists was not different between groups. Results did not differ between peripheral and portal-vein blood of patients (D0, n = 11) and did not change over time (D0, D4, D30) following TIPS implantation (n = 9). In summary, patients with decompensated liver cirrhosis display in vitro platelet aggregation defects in response to various agonists. Defective aggregation persists upon TIPS implantation. Therefore, we conclude that antiplatelet treatment to prevent TIPS thrombosis is questionable.

The use of prothrombin complex concentrate in chronic liver disease: A review of the literature

Patients with chronic liver disease (CLD) and cirrhosis present a rebalanced hemostatic system in the three phases of haemostasis. This balance is however unstable and can easily tip towards bleeding or thrombosis. Management of both spontaneous bleeding and bleeding during invasive procedures remains a challenge in this patient population. Transfusion of blood products can result in circulatory overload and thereby worsen portal hypertension. As an alternative to fresh frozen plasma (FFP), prothrombin complex concentrates (PCC) may have merit in patients with liver disease because of their low volume. The impact of PCC in in-vitro spiking experiments of cirrhotic plasma is promising, but also warrants cautious use in light of thromboembolic risk. The majority of existing studies carried-out in CLD patients are retrospective or do not have an adequate control arm. A prospective study (the PROTON trial) was set up in 2013 to investigate the utility of PCC in patients undergoing liver transplantation. However, the study has never recruited the planned number of patients. Robust data on PCC safety in CLD is also required. The limited existing evidence does not seem to indicate an excessive thromboembolic risk. Currently, the utilisation of PCC in CLD cannot be routinely recommended but can provide an option for carefully selected cases in which other measures were not sufficient to control bleeding and after delicately weighing risks and benefits.

Spontaneous Retroperitoneal Hematoma: A Deadly Complication for Patients Awaiting Liver Transplant

BACKGROUND

Patients with end-stage liver disease (ESLD) are at increased risk for hemorrhage and spontaneous retroperitoneal hematoma (sRPH) and also carry a high mortality rate. We sought to review the natural history of sRPH in patients with ESLD at a single center.

METHODS

All patients admitted to a single transplantation intensive care unit (TICU) at Froedtert and the Medical College of Wisconsin Transplant Center between June 2016 and August 2018 were retrospectively reviewed. Six ESLD patients with sRPH were studied. Clinical outcome measures were liver disease severity, sRPH treatment, and patient survival.

RESULTS

Six patients were included, four male and two female patients, with a median age of 56.5 years (range 30-67 years). All had alcohol-induced liver cirrhosis. The median Model for End-Stage Liver Disease (MELD) score at the time of sRPH diagnosis was 40 (range 30-43). The most commonly identified source of bleeding was from lumbar arteries. One patient had recurrent bleeding after embolization and underwent repeat embolization. Five patients died. The median time to death from the diagnosis of sRPH was 7.2 days (range 2-12 days). The patient who survived following embolization had the lowest MELD score.

CONCLUSION

Critically ill cirrhotic patients with sRPH have a significant mortality rate. Embolization is successful, albeit seldom. This is the largest retrospective series of sRPH in cirrhotic patients in the literature.

Predicting bleeding after liver biopsy using comprehensive clinical and laboratory investigations: A prospective analysis of 302 procedures

BACKGROUND

Liver biopsy carries a small risk of bleeding complications. No validated clinical or laboratory tool helps predict liver biopsy-related bleeding.

OBJECTIVES

To determine whether global hemostasis tests and/or a clinical questionnaire could identify patients at risk of liver biopsy-related bleeding.

PATIENTS/METHODS

Consecutive patients scheduled for liver biopsy with an overnight hospital stay were prospectively included. Before liver biopsy, routine hemostasis tests, Platelet Function Analyzer 100, thromboelastometry, thrombin generation assay, plasma clot lysis time, and a clinical questionnaire were performed. Bleeding was defined as a liver hematoma or new free fluid on a systematic ultrasound performed 24 h after liver biopsy or a decrease in hemoglobin level of 2 g/dL or more in patients with pre-existing free fluid in the abdominal cavity.

RESULTS

Three hundred two patients were included: 173 underwent percutaneous and 129 transjugular liver biopsy. There were 21 bleeding episodes (7%); 20 based on ultrasonographic criteria, 1 on laboratory criteria. None of the hemostasis tests and no item of the clinical questionnaire were associated with liver biopsy-related bleeding in the overall study group. Same results were obtained in subgroup analyses focusing on patients who underwent percutaneous liver biopsy, transjugular liver biopsy, or on patients with cirrhosis. Pain 2 h after liver biopsy was more frequent in patients with liver biopsy-related bleeding (55% vs. 23% p = .002).

CONCLUSIONS

An extensive hemostasis workup, including global hemostasis assays, does not improve prediction of liver biopsy-related bleeding. Pain 2 h after liver biopsy should alert the clinician to the possibility of procedure-related bleeding.

Platelets as a Gauge of Liver Disease Kinetics?

A multitude of laboratory and clinical interferences influence the utility of platelet-based diagnostic indices, including immature platelet fraction, in longitudinal monitoring and prognostication of patients with chronic liver disease (CLD). The complex yet highly regulated molecular basis of platelet production and clearance kinetics becomes dysregulated in liver pathogenesis. These underlying molecular mechanisms, including premature platelet clearance and bone marrow suppression in parallel with the progressive (e.g., treatment-naïve) or regressive (e.g., on-treatment and off-treatment) disease courses, involved in CLDs, may further confound the changes in platelet–liver correlations over time. Platelet count and function are commonly and secondarily altered in vivo in CLDs. However, the precise characterization of platelet functions during cirrhosis, including in vitro platelet aggregation, has proven challenging due to interferences such as thrombocytopenia. A flow cytometric approach may help monitor the unstably rebalanced hyper- and hypoaggregable states in patients with cirrhosis at risk of hyperaggregable, prothrombotic, or bleeding events. Studies have attempted to stratify patients with cirrhosis by substages and prognosis through the use of novel indices such as the ratio of in vitro endogenous platelet aggregation to platelet count. This review attempts to highlight clinical and laboratory precautions in the context of platelet-assisted CLD monitoring.

Peripheral versus central venous blood sampling does not influence the assessment of platelet activation in cirrhosis

Cirrhotic patients have an increased risk of bleeding and thromboembolic events, with platelets being involved as key players in both situations. The impact of peripheral versus central blood sampling on platelet activation remains unclear. In 33 cirrhotic patients, we thus analyzed platelet function in peripheral (P) and central (C) blood samples. Platelet surface expression of P-selectin, activated glycoprotein (GP) IIb/IIIa, and leukocyte-platelet aggregate formation were measured by flow cytometry in response to different agonists: thrombin receptor-activating peptide-6, adenosine diphosphate, collagen-related peptide (CrP), epinephrine, AYPGKF, Pam3CSK4, and lipopolysaccharide. Unstimulated platelet surface expression of P-selectin (p = .850) and activated GPIIb/IIIa (p = .625) were similar in peripheral and central blood samples. Stimulation with various agonists yielded similar results of platelet surface expression of P-selectin and activated GPIIb/IIIa in peripheral and central samples, except for CrP-inducible expression of activated GPIIb/IIIa (median fluorescence intensity, MFI in P: 7.61 [0.00-24.66] vs. C: 4.12 [0.00-19.04], p < .001). The formation of leukocyte-platelet aggregate was similar in central and peripheral blood samples, both unstimulated and after stimulation with all above-mentioned agonists. In conclusion, peripheral vs. central venous blood sampling does not influence the assessment of platelet activation by flow cytometry in cirrhosis.Abbreviations: ACLD: advanced chronic liver disease; ADP: adenosine diphosphate; ALD: alcoholic liver disease; AYPGKF: PAR-4 agonist AYPGKF; CrP: collagen related protein; EPI: epinephrine; FACS: fluorescence-activated cell sorting; GP: glycoprotein; HVPG: hepatic venous pressure gradient; IQR: interquartile range; LPS: lipopolysaccharide; LSM: liver stiffness measurement; MFI: median fluorescence intensity; NAFLD: nonalcoholic fatty liver disease; PAM: lipopeptide Pam3CSK4; PAR: protease-activated receptor; PBS: phosphate-buffered saline; PH: portal hypertension; TIPS: transjugular intrahepatic portosystemic stent shunt; TLR: toll-like receptor; TRAP-6: thrombin receptor-activator peptide-6; vWF: von Willebrand factor.

Flow cytometry for evaluating platelet immunophenotyping and function in patients with thrombocytopenia

Platelets play an essential role in primary hemostasis through bleeding and thromboembolism. Thus, the diagnosis or evaluation of impaired hereditary, acquired, and drug-related platelet dysfunction has become imperative. The assessment of the platelet function is too complex for routine platelet function study. The major methods involved in platelet function study include platelet function analyzer testing, thromboelastography, thromboelastometry, light transmission aggregometry, and flow cytometry. The current review article focuses on the methods with flow cytometry for immunophenotyping of platelet and evaluating platelet function for platelet disorders, especially in patients with thrombocytopenia. According to the consensus published by the International Society on Thrombosis and Haemostasis, for inherited and acquired platelet disorders, the two major measures by which flow cytometry determines platelet function are glycoprotein IIb/IIIa/P-selectin (CD62p) expression and percentage of leukocyte-platelet aggregates. Using flow cytometry to determine platelet function has several advantages, including good sensitivity to low platelet counts, small blood volume required, and the nonnecessity of centrifugation. However, flow cytometry has still many limitations and challenges, with standardization for routine laboratory testing also proving difficult. Although flow cytometry is available for multipurpose and sensitive study of platelet functions at the same time, the challenging analysis gradually increases and needs to be addressed before reality.

Influence of hepatic impairment on the pharmacokinetics and pharmacodynamics of the P2Y12 receptor antagonist selatogrel

Selatogrel is a potent and selective reversible P2Y12 receptor antagonist in development for early treatment of acute myocardial infarction via subcutaneous (s.c.) self‐injection. Selatogrel is almost exclusively eliminated via the hepatobiliary route. Hepatic impairment is associated with reduced drug clearance and primary hemostasis. This single‐center, open‐label study investigated the effect of mild and moderate hepatic impairment on pharmacokinetics (PK) and pharmacodynamics (PD) of a single s.c. dose of selatogrel (16 mg). The study included groups of eight subjects with mild and moderate hepatic impairment, and matched healthy control subjects. Compared to healthy subjects, exposure to selatogrel in subjects with mild and moderate hepatic impairment was 30% and 108% (maximum plasma concentration [C_max]) and 47% and 212% (area under the concentration‐time curve from zero to infinity [AUC_0–∞]) higher, respectively. Hepatic impairment was associated with lower clearance and volume of distribution, whereas plasma protein binding was not affected. Marked inhibition of platelet aggregation (IPA > 80%) was attained within 30 min in all subjects and hepatic impairment prolonged IPA duration. Area under the effect curve was 60% and 160% higher in subjects with mild and moderate hepatic impairment, respectively. PK/PD modeling identified a change in the relationship between exposure and IPA, with a steeper concentration‐effect relationship in healthy subjects compared to subjects with hepatic impairment. The combination of higher exposure and lower half‐maximum inhibitory concentration resulted in longer lasting effect. In conclusion, hepatic impairment alters the PK/PD relationship leading to prolonged effects. Therefore, dose adjustments may be warranted in subjects with moderate hepatic impairment.

Pathophysiology and management of bleeding and thrombosis in patients with liver disease

Patients with liver disease often develop complex changes in their haemostatic system. Frequently observed changes include thrombocytopaenia and altered plasma levels of most of the proteins involved in haemostasis. Although liver disease was historically classified as a haemostasis‐related bleeding disorder, it has now been well established that the antihaemostatic changes that promote bleeding are compensated for by prohaemostatic changes. Conventional coagulation tests however do not accurately reflect these prohaemostatic changes, resulting in an underestimation of haemostatic potential. Novel coagulation tests, such as viscoelastic tests (VETs) and thrombin generation assays (TGAs) better reflect the net result of the haemostatic changes in patients with liver disease, and demonstrate a new, “rebalanced” haemostatic status. Although rebalanced, this haemostatic status is more fragile than in patients without liver disease. Patients with liver disease are therefore not only at risk of bleeding but also at risk of thrombosis. Notably, however, many haemostatic complications in liver disease are not related to the haemostatic failure. It is, therefore, crucial to identify the cause of the bleed or thrombotic complication in order to provide adequate treatment. In this paper, we will elaborate on the haemostatic changes that occur in liver disease, reflect on laboratory and clinical studies over the last few years, and explore the pathophysiologies of bleeding and thrombosis in this specific patient group.

Atrial fibrillation, liver cirrhosis, thrombosis, and bleeding: A Danish population-based cohort study

OBJECTIVES

We examined the impact of liver cirrhosis on the risk of thromboembolic events and bleeding complications in patients with atrial fibrillation or flutter (AFF).

METHODS

This population-based cohort study used data from Danish health registries. We identified all patients with a first-time diagnosis of AFF during 1995 to 2015, and followed them from their AFF diagnosis until the end of 2016. Patients were categorized according to the presence or absence of liver cirrhosis. We computed incidence rates per 1000 person-years and hazard ratios (HRs) with 95% confidence intervals (CIs) based on Cox regression analyses, adjusting for age, CHA2DS2VASc score, and Charlson Comorbidity Index score.

RESULTS

We identified 273 225 patients with AFF. Of these, 1463 (0.54%) had liver cirrhosis. During 0 to 5 years of follow-up, compared to patients without liver cirrhosis, patients with liver cirrhosis had higher incidence rates and hazards of ischemic stroke (29.7 vs 21.6; HR, 1.3; 95% CI, 1.1-1.6), venous thromboembolism (9.2 vs 5.5; HR, 1.5; 95% CI, 1.2-2.3), but not myocardial infarction (10.2 vs 11.2; HR, 0.9; 95% CI, 0.7-1.2). Patients with liver cirrhosis also had higher rates of hemorrhagic stroke (5.8 vs 3.3; HR, 1.7; 95% CI, 1.1-2.6), subdural hemorrhage (5.3 vs 1.6; HR, 3.2; 95% CI, 2.1-4.9), hemorrhage of the lung or urinary tract (24.6 vs 15.2; HR, 1.6; 95% CI, 1.3-2.0), and gastrointestinal hemorrhage (34.5 vs 10.4; HR, 3.3; 95% CI, 2.7-3.9).

CONCLUSION

In patients with AFF, liver cirrhosis was associated with an elevated risk of ischemic stroke, venous thromboembolism, and all evaluated bleeding complications.

Relationship Between Platelet to White Blood Cell Ratio and 30-Day Prognosis of Patients with Acute-on-Chronic Liver Failure

Background: Acute-on-chronic liver failure (ACLF) is always associated with thrombocytopenia or leukocytosis. Therefor the platelet to white blood cell ratio (PWR) in ACLF patients is always reduced. Objectives: Here, we assessed the relationship between PWR and prognosis in ACLF patients. Methods: A retrospective cohort of 415 patients, including 100 patients that were diagnosed of chronic hepatitis B, 104 patients suffered of HBV-related liver cirrhosis and 211 patients suffered of HBV-related ACLF, was investigated. Univariate and multivariate COX models were used to investigate the relationship between PWR and 30-day survival in patients with ACLF. Factors affecting PWR in ACLF patients were also analysed using logistic regression analysis. Results: At baseline, the platelet count in patients with HBV-related ACLF was significantly lower than that in patients with CHB and patients suffered of HBV-related cirrhosis. The PWR value was much higher in the survivors of ACLF than in ACLF patients who died. PWR, age, total bilirubine, prothrombin activity, and aspartate transaminase were independent predictors of the 30-day survival rate of ACLF patients. We also found that ascites and infection were independent factors related to the decrease of PWR in ACLF patients. Conclusions: The PWR value was significant declined in ACLF patients. And it was independent risk factors for the survival rate of those patients.

The hemostatic and thrombotic complications of liver disease

Hepatic cirrhosis leads to numerous hematologic derangements resulting in a complex and tenuously rebalanced hemostatic milieu. The utility of common hematologic tests including the INR and aPTT in assessing hemostatic and thrombotic risk in patients with cirrhosis is limited, and consensus on transfusion thresholds and proper management of thrombotic complications continues to evolve. This review summarizes the pathophysiology of key derangements of hemostasis including those of platelets, von Willebrand factor, pro- and anticoagulation factors, and fibrin. Additionally, the pathogenesis, consequences, optimal management, and prevention of major thrombotic and bleeding complications in cirrhosis arte discussed.

Short-term standard alcohol consumption enhances platelet response to clopidogrel through inhibition of Nrf2/Ces1 pathway and induction of Cyp2c in mice

AIMS

Drinking alcohol is prevalent worldwide; however, it is unknown whether alcohol could affect the antiplatelet effects of clopidogrel in patients when taking both concomitantly. This study was designed to investigate the influence of short-term standard alcohol consumption on the metabolic activation of and platelet response to clopidogrel in mice as well as the mechanisms involved.

MAIN METHODS

Male C57BL/6J mice were administered with normal saline (vehicle control) or alcohol at 2 g/kg/day for 7 days, and then gavaged with vehicle control or a single dose of clopidogrel at 10 mg/kg. Inhibition of ADP-induced platelet aggregation and activation by clopidogrel, plasma concentrations of clopidogrel and its active metabolite H4, and changes in mRNA and protein expression of genes related to clopidogrel metabolism and its regulation were measured in mice pretreated with or without alcohol.

KEY FINDINGS

Compared with vehicle control, alcohol pretreatment significantly reduced hydrolysis of clopidogrel as a result of significant down-regulation of Nrf2-mediated Ces1 expression (responsible for the formation of clopidogrel carboxylate), increased metabolic activation of clopidogrel due to significant up-regulation of Cyp2c (for the formation of active thiol metabolite H4), and consequently enhanced inhibition of ADP-induced platelet aggregation and activation by clopidogrel.

SIGNIFICANCE

Short-term standard alcohol consumption would significantly enhance suppression of ADP-induced platelet aggregation and activation by clopidogrel through significant inhibition of Nrf2/Ces1 signaling pathway and induction of Cyp2c, suggesting that alcohol may interact with drugs that are predominantly metabolized by CES1 or CYP2C in patient care, including clopidogrel.

Assessing the Prediction Effect of Various Prognosis Model for 28-Day Mortality in Acute-on-Chronic Liver Failure Patients

Background

Acute-on-chronic liver failure (ACLF) is an extremely clinical entity associated with short-term high mortality. The CLIF-SOFA score measures both hepatic and extrahepatic organ dysfunction and can discriminate significantly better between survivors and nonsurvivors compared to other methods. The MELD score is widely used for organ allocation in liver transplantation. Recent reports indicate that the PWR is a potential biomarker for predicting clinical outcomes. The ALBI score is a new score model for evaluating the severity of liver dysfunction. We aimed to compare these prognosis models to predict short-term mortality in ACLF patients.

Methods

A retrospective analysis of 89 ACLF patients between 2015 and 2018 was performed. The receiver operating characteristic (ROC) curve was used to assess the power of four prognosis models for predicting 28-day mortality in patients with ACLF.

Results

The ALBI score, MELD score and CLIF-SOFA score were significantly higher, and the PWR was slightly lower in nonsurviving ACLF patients than in surviving patients. The MELD score and ALBI score were positively correlated with the CLIF-SOFA score, while the PWR was inversely related to the CLIF-SOFA score. The area under the ROC curves (AUROCS) of the CLIF-SOFA score, PWR, ALBI score and MELD score were 0.804, 0.759, 0.710 and 0.670, respectively.

Conclusion

The CLIF-SOFA score, PWR and ALBI score can better predict 28-day mortality in ACLF patients, but the MELD score has worse predictability. The CLIF-SOFA score is the best prognosis model among these models. PWR may be a simple and useful tool that can predict 28-day outcome.

Longitudinal decrease in platelet counts as a surrogate marker of liver fibrosis

BACKGROUND

Liver cirrhosis is a significant source of morbidity and mortality worldwide. The disease is usually indolent and asymptomatic early in its course while many cirrhotic patients are diagnosed late when severe complications occur. A major challenge is to diagnose advanced fibrosis as early as possible, using simple and non-invasive diagnostics tools. Thrombocytopenia represents advanced fibrosis and portal hypertension (HTN) and most non-invasive scores that predict liver fibrosis incorporate platelets as a strong risk factor. However, little is known about the association between longitudinal changes in platelet counts (PTC), when still within the normal range, and the risk of cirrhosis.

AIM

To explore whether platelet counts trajectories over time, can predict advanced liver fibrosis across the different etiologies of liver diseases.

METHODS

A nested case-control study utilizing a large computerized database. Cirrhosis cases (n = 5258) were compared to controls (n = 15744) matched for age and sex at a ratio of 1:3. All participants had multiple laboratory measurements prior to enrollment. We calculated the trends of PTC, liver enzymes, bilirubin, international normalized ratio, albumin and fibrosis scores (fibrosis-4 and aspartate transaminase-to-platelet ratio index) throughout the preceding 20 years prior to cirrhosis diagnosis compared to healthy controls. The association between PTC, cirrhosis complications and fibrosis scores prior to cirrhosis diagnosis was investigated.

RESULTS

The mean age in both groups was 56 (SD 15.8). Cirrhotic patients were more likely to be smokers, diabetic with chronic kidney disease and had a higher prevalence of HTN. The leading cirrhosis etiologies were viral, alcoholic and fatty liver disease. The mean PTC decreased from 240000/μL to 190000/μL up to 15 years prior to cirrhosis diagnosis compared to controls who’s PTC remained stable around the values of 240000/μL. This trend was consistent regardless of sex, cirrhosis etiology and was more pronounced in patients who developed varices and ascites. Compared to controls whose values remained in the normal range, in the cirrhosis group aspartate aminotransferase and alanine aminotransferase, increased from 40 U/L to 75 U/L and FIB-4 increased gradually from 1.3 to 3 prior to cirrhosis diagnosis. In multivariable regression analysis, a decrease of 50 units in PTC was associated with 1.3 times odds of cirrhosis (95%CI 1.25-1.35).

CONCLUSION

In the preceding years before the diagnosis of cirrhosis, there is a progressive decline in PTC, within the normal range, matched to a gradual increase in fibrosis scores.

Platelet Function Analysis by Flowcytometry in Thrombocytopenic Trauma Patients

Hemostasis is dependent on sufficient quantity and quality of circulating functional platelets. Platelet function in trauma patients with thrombocytopenia and its impact on the clinical outcome is not adequately explored. Whether platelet dysfunction has a role in the pathogenesis of acute traumatic coagulopathy needs to be studied. Blood samples were collected from 70 thrombocytopenic trauma patients before transfusing platelets and assessed for platelet activation and platelet aggregation using flowcytometry. Primary outcome was in-hospital mortality. Platelet dysfunction was identified in 57.1% of thrombocytopenic trauma patients. A weak inverse correlation between percentage of activated platelets and APTT was observed (Spearman coefficient - 0.25, p = 0.03). A sensitivity and specificity of 66.6% was achieved for a cut off of ≤ 6.5% of platelet activation post trauma with ROC-AUC of 0.658 for identifying coagulopathy. No correlation with mortality however was observed (p > 0.05). Platelet dysfunction had a weak association with coagulopathy suggesting limited contribution of platelet dysfunction in pathogenesis of acute traumatic coagulopathy and warrants further research.

Thromboelastography maximum amplitude predicts short-term mortality in patients with hepatitis B virus-related acute-on-chronic liver failure

Patients with hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF) exhibit complex hemostatic defects. Thromboelastography (TEG) can be used to reveal global hemostasis in patients with liver disease; however, little is known about the association between TEG and the outcome of patients with HBV-related ACLF. The present study aimed to investigate the value of TEG for predicting 90 day mortality in patients with HBV-related ACLF. A total of 51 patients with HBV-related ACLF, 26 patients with chronic hepatitis B (CHB) and 26 healthy controls (HC) were enrolled in the present study. TEG, standard coagulation tests, routine blood tests, biochemical markers and demographic variables were recorded and assessed for prognostic value. The results indicated that a prolonged reaction and kinetics (K) time, a shortened α angle and a decreased maximum amplitude (MA) and coagulation index (CI) were observed in patients with HBV-related ACLF, compared with CHB and HC subjects. Patients with HBV-related ACLF in the mortality group exhibited a decrease in α angle, MA, lysis at 30 min, CI, fibrinogen and platelet count, and an increase in K time, international normalized ratio (INR) and the model for end-stage liver disease (MELD) score in comparison with the survival group. MA and INR were two independent predictors of 90 day mortality in patients with HBV-related ACLF, with hazard ratios of 0.918 (95% CI, 0.867-0.971; P=0.003) and 3.141 (95% CI, 1.843-5.354; P<0.001) respectively. When predicting 90 day mortality, MA + INR exhibited the highest area under the receiver operating characteristic curve, followed by INR, MELD score and MA. Patients with ACLF and MA ≤51.5 mm exhibited a poorer outcome than those with MA >51.5 mm, as revealed via the Kaplan-Meier analysis. In summary, the findings of the present study suggested that TEG MA was associated with 90 day mortality in patients with HBV-related ACLF, and a combination of MA and INR was superior to MA, INR and MELD score in terms of prognostic value.

Hemostatic Alterations in Patients With Cirrhosis: From Primary Hemostasis to Fibrinolysis

In the setting of liver cirrhosis (LC), profound hemostatic changes occur, which affect primary hemostasis, coagulation, and fibrinolysis. They involve prohemorrhagic and prothrombotic alterations at each of these steps. Patients with cirrhosis exhibit multifactorial thrombocytopenia and in vitro thrombocytopathy, counterbalanced by increased von Willebrand factor. The resultant shift is difficult to assess, but overall these changes probably result in a rebalanced primary hemostasis. Concerning coagulation, the reduced activity of coagulation factors is counterbalanced by an increase in factor VIII (produced by liver sinusoidal endothelial cells), a decrease of the natural anticoagulants, and complex changes, including changes in circulating microparticles, cell-free DNA, and neutrophil extracellular traps. Overall, these alterations result in a procoagulant state. As for fibrinolysis, increased tissue-type and urokinase-type plasminogen activators, a relatively decreased plasminogen activator inhibitor 1, and decreased levels of thrombin-activatable fibrinolysis inhibitor and α2-antiplasmin are counterbalanced by decreased plasminogen and a decreased fibrin clot permeability. Whether and how these changes shift fibrinolysis remains to be determined. Overall, the current consensus is that in patients with cirrhosis, the hemostasis is shifted toward a procoagulant state. We review the published evidence for the concept of LC as a prothrombotic state, discuss discordant data, and highlight the impact of the underlying cause of LC on the resultant imbalance.

Primary Hemostasis in Chronic Liver Disease and Cirrhosis: What Did We Learn over the Past Decade?

Changes in primary hemostasis have been described in patients with chronic liver disease (CLD) and cirrhosis and are still subject to ongoing debate. Thrombocytopenia is common and multifactorial. Numerous studies also reported platelet dysfunction. In spite of these changes, primary hemostasis seems to be balanced. Patients with CLD and cirrhosis can suffer from both hemorrhagic and thrombotic complications. Variceal bleeding is the major hemorrhagic complication and is mainly determined by high portal pressure. Non portal hypertension-related bleeding due to hemostatic failure is uncommon. Thrombocytopenia can complicate management of invasive procedures in CLD patients. Recently, oral thrombopoietin agonists have been approved to raise platelets before invasive procedures. In this review we aim to bundle literature, published over the past decade, discussing primary hemostasis in CLD and cirrhosis including (1) platelet count and the role of thrombopoietin (TPO) agonists, (2) platelet function tests and markers of platelet activation, (3) von Willebrand factor and (4) global hemostasis tests.

Platelet activating factor receptor acts to limit colitis-induced liver inflammation

Liver inflammation is a common extraintestinal manifestation in inflammatory bowel disease (IBD), yet, the mechanisms driving gut-liver axis inflammation remain poorly understood. IBD leads to a breakdown in the integrity of the intestinal barrier causing an increase in portal and systemic gut-derived antigens, which challenge the liver. Here, we examined the role of platelet activating factor receptor (PAFR) in colitis-associated liver damage using dextran sulfate sodium (DSS) and anti-CD40-induced colitis models. Both DSS and anti-CD40 models exhibited liver inflammation associated with colitis. Colitis reduced global PAFR protein expression in mouse livers causing an exclusive re-localization of PAFR to the portal triad. The global decrease in liver PAFR was associated with increased sirtuin 1 while relocalized PAFR expression was limited to Kupffer cells (KCs) and co-localized with toll-like receptor 4. DSS activated the NLRP3-inflammasome and increased interleukin (IL)-1β in the liver. Antagonism of PAFR amplified the inflammasome response by increasing NLRP3, caspase-1, and IL-1β protein levels in the liver. LPS also increased NLRP3 response in human hepatocytes, however, overexpression of PAFR restored the levels of NLPR3 and caspase-1 proteins. Interestingly, KCs depletion also increased IL-1β protein in mouse liver after DSS challenge. These data suggest a protective role for PAFR-expressing KCs during colitis and that regulation of PAFR is important for gut-liver axis homeostasis.

Platelet aggregation is not altered among men with diabetes mellitus

AIMS

Platelets are pivotal in arterial thrombosis, and platelet hyperresponsiveness may contribute to the increased incidence of cardiovascular events in diabetes mellitus. Consequently, we hypothesized that increased in vitro platelet aggregation responses exist in men with diabetes mellitus.

METHODS

The Danish Cardiovascular Screening Trial (DANCAVAS) is a community-based cardiovascular screening trial including men aged 65-74 years. Platelet aggregation was tested using 96-well light transmission aggregometry with thrombin receptor-activating peptide (TRAP), adenosine diphosphate, collagen type 1, arachidonic acid and protease-activated receptor-4 in three concentrations. Further, cardiovascular risk factors and coronary artery calcification (CAC), estimated by CT scans and ankle-brachial index, were obtained.

RESULTS

Included were 720 men aged 65-74 years, 110 with diabetes mellitus. Overall, there was no difference in platelet aggregation among men with versus without diabetes mellitus when adjusting for or excluding platelet inhibitor treatment and men with established cardiovascular disease (CVD). This was true for all agonists, e.g., 10 µM TRAP-induced platelet aggregation of median 69% (IQR 53-75) versus 70% (IQR 60-76) in men with versus without diabetes mellitus. Platelet aggregation did not correlate with HbA_1c or CAC. Men with diabetes mellitus displayed higher CAC, median 257 Agatston units (IQR 74-1141) versus median 111 Agatston units (IQR 6-420) in the remaining individuals, p < 0.0001.

CONCLUSIONS

Among outpatients with diabetes mellitus, but no CVD and no platelet inhibitor treatment, neither are platelets hyperresponsive in diabetes mellitus, nor is platelet aggregation associated with glycemic status or with the degree of coronary atherosclerosis.

TRIAL REGISTRATION

ISRCTN12157806.

Improvement of human platelet aggregation post-splenectomy with paraesophagogastric devascularization in chronic hepatitis B patients with cirrhotic hypersplenism

Thrombocytopenia is a common hematological abnormality in patients with cirrhotic hypersplenism. Splenectomy with paraesophagogastric devascularization (SPD) is a conventional surgical therapy which can reverse pancytopenia in these patients. Platelets are traditionally recognized for their central role in hemostasis. However, the status of platelet aggregation in chronic hepatitis B patients with cirrhotic hypersplenism before and after SPD has not been reported yet. A total of 41 cirrhotic patients and 31 healthy controls were included in this study. Platelet aggregation was detected by AggRAM® Advanced Modular System (Helena Laboratories, USA). ELISA was used to detect the cytokines closely related to platelet aggregation. Expressions of platelet membrane glycoproteins (GPs) were evaluated by flow cytometric analysis. Platelet aggregation was found to be decreased distinctly in the cirrhotic patients, and to be restored to normal level after SPD. The cirrhotic patients showed higher plasma levels of the cytokines HMGB1, PEDF, vWF, cAMP and cGMP, which also improved partially after SPD. Moreover, the cirrhotic patients had much lower expression of GPIIb/IIIa, GPIbα and P-selectin than either the healthy controls or SPD patients at basal or activated level. Generally, SPD benefits cirrhotic patients with bleeding tendencies by improving platelet counts and aggregation. GPIIb/IIIa may be the key membrane protein responsible for the change in platelet aggregation before and after SPD.

Platelets in chronic liver disease, from bench to bedside

In the last decade, numerous studies revealed physiologic and pathophysiologic roles of platelets beyond haemostasis, a process to prevent and stop bleeding. These include the activation of the immune system and the promotion of inflammation, infection and cancer. Hence, the emerging view on the role of platelets has shifted - platelets are now seen as alert "sentinels" of the immune compartment, rather than passive bystanders. Herein, we review well-established and newly discovered features of platelets that define their natural role in maintaining blood haemostasis, but also their functional relationship with other cells of the immune system. We focus on recent studies underlining functional involvement of platelets in chronic liver diseases and cancer, as well as the effects of anti-platelet therapy in these contexts. Finally, we illustrate the potential of platelets as possible diagnostic and therapeutic tools in liver disease based on recently developed methodologies.

Enhanced processing of von Willebrand factor reflects disease severity and discriminates severe portal hypertension in cirrhosis

OBJECTIVES

Portal hypertension in cirrhosis is associated with endothelial dysfunction, impaired wound healing, and decreased platelet count. Increased von Willebrand factor (VWF) formation has been suggested as a compensatory mechanism, but the role of VWF processing has not been directly assessed. The aim was to measure the processing of activated VWF (VWF-A) in addition to VWF release (VWF-N) to investigate the association of primary hemostasis with disease activity and portal hypertension in liver cirrhosis.

PARTICIPANTS AND METHODS

Plasma samples from 105 participants undergoing liver vein catheterization and with liver cirrhosis of varying severity were included in the study together with 20 controls without liver disease. Competitive enzyme-linked immunosorbent assay format was used to estimate biomarkers of VWF turnover using neo-epitope-specific monoclonal antibodies.

RESULTS

VWF-N levels and VWF-A levels were significantly elevated in cirrhotic patients compared with controls (P<0.0001), and both markers could discriminate mild from severe cirrhosis (VWF-N, P<0.0001; VWF-A, P<0.05). Both markers correlated well with increasing portal hypertension and could identify patients with clinically significant portal hypertension (VWF-N, area under the curve: 0.78; VWF-A, area under the curve: 0.67). Only VWF-A significantly separated compensated from decompensated patients (P<0.05).

CONCLUSION

The data indicate that both VWF release and processing of active VWF are increased in cirrhosis, reflecting ongoing wound healing initiation. VWF-N and VWF-A may specifically contain information to assess the presence and severity of PHT as an early indicator of cirrhosis, and for acute damage in decompensated cirrhosis. Whether the increased wound healing affects long-term outcome needs to be addressed in future studies.

Acquired platelet function disorders

The possibility of an acquired platelet function disorder should be considered in patients who present with recent onset muco-cutaneous bleeding. Despite the availability of newer and faster platelet function assays, light transmission aggregometry (LTA) remains the preferred diagnostic test. This review examines and discusses the causes of acquired platelet dysfunction; most commonly drugs, dietary factors, medical disorders and procedures. In addition to well-known antiplatelet therapies, clinicians should be alert for newer drugs which can affect platelets, such as ibrutinib. There is little clinical trial evidence to guide the management of acquired platelet function defects, but we summarise commonly employed strategies, which include addressing the underlying cause, antifibrinolytic agents, desmopressin infusions, and in selected patients, platelet transfusions.