Thrombopoietin induces rapid resolution of thrombocytopenia after orthotopic liver transplantation through increased platelet production

Cytopenias in Autoimmune Liver Diseases-A Review

Autoimmune liver diseases (AiLDs), including autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC), are immune-mediated conditions associated with significant hepatic and systemic manifestations. Among these, cytopenias-defined as reductions in blood cell counts affecting single or multiple lineages-represent a clinically important, though often under-recognized, complication. Cytopenias in AiLDs arise from diverse mechanisms, including immune-mediated destruction, hypersplenism due to portal hypertension, bone marrow suppression, and nutritional deficiencies. These abnormalities can exacerbate bleeding, infections, or fatigue, complicating the disease course and impacting therapeutic strategies. Immune-mediated cytopenias, such as autoimmune hemolytic anemia (AIHA), immune thrombocytopenic purpura (ITP), and autoimmune neutropenia (AIN), are more frequently associated with AIH, whereas cytopenias in PBC and PSC are largely attributed to hypersplenism. Diagnostic evaluation involves a systematic approach combining clinical history, laboratory testing (e.g., complete blood counts, Coombs tests, and nutritional assessments), imaging studies, and bone marrow evaluation in complex cases. Treatment strategies aim to address the underlying cause of cytopenias, including immunosuppressive therapy for autoimmune mechanisms, beta-blockers or splenectomy for hypersplenism, and supplementation for nutritional deficiencies. Challenges include distinguishing between immune- and hypersplenism-related cytopenias, managing drug-induced cytopenias, and optimizing care in transplant candidates. The recently recognized IgG4-related disease, often mimicking cholestatic AiLDs, adds another layer of complexity, given its association with autoimmune cytopenias and hypersplenism. This review aims to act as a guide for the clinician dealing with patients with AiLDs with respect to the occurrence of cytopenias, with a specific focus on pathophysiology and management of these cytopenias. Furthermore, there need to be enhanced multidisciplinary discussions about those patients between the hematologists and hepatologists, with a maintenance of a high index of suspicion for the rarer causes of cytopenias in AiLDs on the part of the treating physician, and there is a need for further studies to elucidate the mechanisms behind the occurrence of cytopenias in AiLDs.

LMAN1 serves as a cargo receptor for thrombopoietin

Thrombopoietin (TPO) is a plasma glycoprotein that binds its receptor on megakaryocytes (MKs) and MK progenitors, resulting in enhanced platelet production. The mechanism by which TPO is secreted from hepatocytes remains poorly understood. Lectin mannose-binding 1 (LMAN1) and multiple coagulation factor deficiency 2 (MCFD2) form a complex at the endoplasmic reticulum membrane, recruiting cargo proteins into COPII vesicles for secretion. In this study, we showed that LMAN1-deficient mice (with complete germline LMAN1 deficiency) exhibited mild thrombocytopenia, whereas the platelet count was entirely normal in mice with approximately 7% Lman1 expression. Surprisingly, mice deleted for Mcfd2 did not exhibit thrombocytopenia. Analysis of peripheral blood from LMAN1-deficient mice demonstrated normal platelet size and normal morphology of dense and alpha granules. LMAN1-deficient mice exhibited a trend toward reduced MK and MK progenitors in the bone marrow. We next showed that hepatocyte-specific but not hematopoietic Lman1 deletion results in thrombocytopenia, with plasma TPO level reduced in LMAN1-deficient mice, despite normal Tpo mRNA levels in LMAN1-deficient livers. TPO and LMAN1 interacted by coimmunoprecipitation in a heterologous cell line, and TPO accumulated intracellularly in LMAN1-deleted cells. Together, these studies verified the hepatocyte as the cell of origin for TPO production in vivo and were consistent with LMAN1 as the endoplasmic reticulum cargo receptor that mediates the efficient secretion of TPO. To our knowledge, TPO is the first example of an LMAN1-dependent cargo that is independent of MCFD2.

EASL Clinical Practice Guidelines on liver transplantation

Liver transplantation (LT) is an established life-saving procedure. The field of LT has changed in the past 10 years from several perspectives, with the expansion of indications, transplantation of patients with acute-on-chronic liver failure, evolution of transplant oncology, the use of donations after cardiac death, new surgical techniques, and prioritisation of recipients on the waiting list. In addition, the advent of organ perfusion machines, the recognition of new forms of rejection, and the attention paid to the transition from paediatric to adult patients, have all improved the management of LT recipients. The purpose of the EASL guidelines presented here is not to cover all aspects of LT but to focus on developments since the previous EASL guidelines published in 2016.

Evidence for platelet-derived transforming growth factor β1 as an early inducer of liver regeneration after hepatectomy in mice

Platelets play a crucial role in tissue regeneration, and their involvement in liver regeneration is well-established. However, the specific contribution of platelet-derived Transforming Growth Factor Beta 1 (TGFβ1) to liver regeneration remains unexplored. This study investigated the role of platelet-derived TGFβ1 in initiating liver regeneration following 2/3 liver resection. Using platelet-specific TGFβ1 knockout (Plt.TGFβ1 KO) mice and wild-type littermates (Plt.TGFβ1 WT) as controls, the study assessed circulating levels and hepatic gene expression of TGFβ1, Platelet Factor 4 (PF4), and Thrombopoietin (TPO) at early time points post-hepatectomy (post-PHx). Hepatocyte proliferation was quantified through Ki67 staining and PCNA expression in total liver lysates at various intervals, and phosphohistone-H3 (PHH3) staining was employed to mark mitotic cells. Circulating levels of hepatic mitogens, Hepatocyte Growth Factor (HGF), and Interleukin-6 (IL6) were also assessed. Results revealed that platelet-TGFβ1 deficiency significantly reduced total plasma TGFβ1 levels at 5 h post-PHx in Plt.TGFβ1 KO mice compared to controls. While circulating PF4 levels, liver platelet recruitment and activation appeared normal at early time points, Plt.TGFβ1 KO mice showed more stable circulating platelet numbers with higher numbers at 48 h post-PHx. Notably, hepatocyte proliferation was significantly reduced in Plt.TGFβ1 KO mice. The results show that a lack of TGFβ1 in platelets leads to an unbalanced expression of IL6 in the liver and to strongly increased HGF levels 48 h after liver resection, and yet liver regeneration remains reduced. The study identifies platelet-TGFβ1 as a regulator of hepatocyte proliferation and platelet homeostasis in the early stages of liver regeneration.

From Cirrhosis to the Dysbiosis (A Loop of Cure or Complications?)

Gut dysbiosis and liver cirrhosis are two corelated complications that highly disturbs the metabolism of a normal human body. Liver cirrhosis is scarring of the hepatic tissue and gut dysbiosis is the imbalance in the microbiome of the gut. Gut dysbiosis in cirrhosis occurs due to increased permeability of the intestinal membrane which might induce immune responses and damage the normal functioning of the body. Dysbiosis can cause liver damage from cirrhosis and can further lead to liver failure by hepatocellular carcinoma. In this review we discuss if eubiosis can revert the poorly functioning cirrhotic liver to normal functioning state? A normal microbiome converts various liver products into usable forms that regulates the overgrowth of microbiome in the gut. The imbalance caused by dysbiosis retards the normal functioning of liver and increases the complications. To correct this dysbiosis, measures like use of antibiotics with probiotics and prebiotics are used. This correction of the gut microbiome serves as a ray of hope to recover from this chronic illness. In case of alcohol induced liver cirrhosis, intervention of microbes can possibly be helpful in modulating the addiction as well as associated complications like depression as microbes are known to produce and consume neurotransmitters that are involved in alcohol addiction. Hence a correction of gut liver brain axis using microbiome can be a milestone achieved not only for treatment of liver cirrhosis but also for helping alcohol addicts quit and live a healthy or at least a near healthy life.

Correction of Thrombocytopenia before Elective Surgery / Invasive Procedures in Patients with Liver Cirrhosis (Experts’ Agreement)

Introduction. As a result of portal hypertension (sequestration of platelets in an enlarged spleen) and liver failure (decreased production of thrombopoietin in the liver) in liver cirrhosis, thrombocytopenia develops, which is associated with the risk of periprocedural/perioperative bleeding complications. There are still unresolved questions regarding risk stratification of bleeding complications, the prognostic role of thrombocytopenia, as well as the need for treatment of thrombocytopenia and its methods.

Materials and methods. The Russian Scientific Liver Society selected a panel of experts in the field of therapeutic and surgical hepatology, hematology, transfusion medicine to make reasoned statements and recommendations on the issue of treatment of thrombocytopenia before elective surgery / invasive procedures in patients with liver cirrhosis.

Results. Relevant clinical issues were determined based on the PICO principle (patient or population, intervention, comparison, outcome). The Delphi panel made five questions and gave reasoned answers, framed as ‘clinical practice recommendations and statements’ with evidence-based comments. The questions and statements were based on the results of search and critical analysis of medical literature using keywords in English- and Russian-language databases. The formulated questions could be combined into four categories: bleeding risk stratification, the prognostic value of thrombocytopenia, the necessity and methods of thrombocytopenia drug correction, and bleeding risk reduction.

Conclusions. The results of experts' work are directly related to high-quality management of patients with liver cirrhosis and thrombocytopenia, who have scheduled invasive procedures/surgery. Thus, this recommendations and statements can be used in clinical practice.

Biomarkers of Hepatic Toxicity: An Overview

Background

Hepatotoxicity is the foremost issue for clinicians and the primary reason for pharmaceutical product recalls. A biomarker is a measurable and quantifiable attribute used to evaluate the efficacy of a treatment or to diagnose a disease. There are various biomarkers which are used for the detection of liver disease and the intent of liver damage.

Objective

This review aims to investigate the current state of hepatotoxicity biomarkers and their utility in clinical settings. Using hepatic biomarkers, the presence of liver injury, its severity, prognosis, causative agent, and type of hepatotoxicity can all be determined.

Methods

Relevant published articles up to 2022 were systematically retrieved from MEDLINE/PubMed, SCOPUS, EMBASE, and WOS databases using keywords such as drug toxicity, hepatotoxicity biomarkers, biochemical parameters, and nonalcoholic fatty liver disease.

Results

In clinical trials and everyday practice, biomarkers of drug-induced liver injury are essential for spotting the most severe cases of hepatotoxicity. Hence, developing novel biomarker approaches to enhance hepatotoxicity diagnosis will increase specificity and/or identify the person at risk. Importantly, early clinical studies on patients with liver illness have proved that some biomarkers such as aminotransferase, bilirubin, albumin, and bile acids are even therapeutically beneficial.

Conclusions

By assessing the unique signs of liver injury, health care professionals can rapidly and accurately detect liver damage and evaluate its severity. These measures contribute to ensuring prompt and effective medical intervention, hence reducing the risk of long-term liver damage and other major health concerns.

Thrombocytopenia and liver disease: pathophysiology and periprocedural management

Abnormal bleeding in patients with liver disease may result from elevated portal pressure and varix formation, reduced hepatic synthesis of coagulation proteins, qualitative platelet dysfunction, and/or thrombocytopenia. Major mechanisms of thrombocytopenia in liver disease include splenic sequestration and impaired platelet production due to reduced thrombopoietin production. Alcohol and certain viruses may induce marrow suppression. Immune thrombocytopenia (ITP) may co-occur in patients with liver disease, particularly those with autoimmune liver disease or chronic hepatitis C. Drugs used for the treatment of liver disease or its complications, such as interferon, immunosuppressants, and antibiotics, may cause thrombocytopenia. Periprocedural management of thrombocytopenia of liver disease depends on both individual patient characteristics and the bleeding risk of the procedure. Patients with a platelet count higher than or equal to 50 000/µL and those requiring low-risk procedures rarely require platelet-directed therapy. For those with a platelet count below 50 000/µL who require a high-risk procedure, platelet-directed therapy should be considered, especially if the patient has other risk factors for bleeding, such as abnormal bleeding with past hemostatic challenges. We often target a platelet count higher than or equal to 50 000/µL in such patients. If the procedure is elective, we prefer treatment with a thrombopoietin receptor agonist; if it is urgent, we use platelet transfusion. In high-risk patients who have an inadequate response to or are otherwise unable to receive these therapies, other strategies may be considered, such as a trial of empiric ITP therapy, spleen-directed therapy, or transjugular intrahepatic portosystemic shunt placement.

Different impacts of common risk factors associated with thrombocytopenia in patients with hepatitis B virus and hepatitis C virus infection

BACKGROUND

Thrombocytopenia is a common extrahepatic manifestation in chronic liver disease. However, there have been rare studies of impacts of risk for hepatitis C virus-associated thrombocytopenia (HCV-TP) and hepatitis B virus-associated thrombocytopenia (HBV-TP). The aim of this study is to evaluate different impacts of risk factors for HCV-TP and HBV-TP.

METHODS

We retrospectively collected 1803 HCV patients and 1652 HBV patients to examine the risk factors for time to moderate and severe thrombocytopenia (platelet counts <100 × 109/L and <50 × 109/L, respectively) by Cox proportional hazards models. Moreover, we prospectively enrolled 63 HCV-TP patients, 11 HBV-TP patients, and 27 HCV controls to detect specific antiplatelet antibodies by enzyme-linked immunosorbent assay and analyze their effects.

RESULTS

Prevalence of platelet <100 × 109/L was 11.86% and 6.35% in HCV and HBV patients without cancer history, respectively. HCV-to-HBV incidence rate ratio for thrombocytopenia was 6.95. Initial thrombocytopenia was the most significant risk factor for HCV-TP and HBV-TP regardless of thrombocytopenia severity. Splenomegaly and cirrhosis were significant risk factors for moderate, but not severe HCV-TP. Hyperbilirubinemia was an important moderate and severe HBV-TP risk factor. Antiplatelet antibodies were correlated with HCV-TP severity, of which anti-glycoprotein IIb/IIIa antibody being associated with smaller spleen size. The antiplatelet autoantibody might contribute to thrombocytopenia either independently or with splenomegaly as the important risk in HCV-TP patients without advanced cirrhosis.

CONCLUSION

HCV was associated with higher thrombocytopenia incidence than HBV. Thrombocytopenia risk factors varied with virus type and severity. Different management for HCV-TP and HBV-TP was suggested.

Treatment of drug-induced immune thrombocytopenias

Several therapeutic agents can cause thrombocytopenia by either immune-mediated or non-immune-mediated mechanisms. Non-immune-mediated thrombocytopenia is due to direct toxicity of drug molecules to platelets or megakaryocytes. Immune-mediated thrombocytopenia, on the other hand, involves the formation of antibodies that react to platelet-specific glycoprotein complexes, as in classic drug-induced immune thrombocytopenia (DITP), or to platelet factor 4, as in heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombotic thrombocytopenia (VITT). Clinical signs include a rapid drop in platelet count, bleeding or thrombosis. Since the patient's condition can deteriorate rapidly, prompt diagnosis and management are critical. However, the necessary diagnostic tests are only available in specialized laboratories. Therefore, the most demanding step in treatment is to identify the agent responsible for thrombocytopenia, which often proves difficult because many patients are taking multiple medications and have comorbidities that can themselves also cause thrombocytopenia. While DITP is commonly associated with an increased risk of bleeding, HIT and VITT have a high mortality rate due to the high incidence of thromboembolic complications. A structured approach to drug-associated thrombocytopenia/thrombosis can lead to successful treatment and a lower mortality rate. In addition to describing the treatment of DITP, HIT, VITT, and vaccine-associated immune thrombocytopenia, this review also provides the pathophysiological and clinical information necessary for correct patient management.

Treatment of chemotherapy-induced thrombocytopenia in patients with non-hematologic malignancies

Chemotherapy-induced thrombocytopenia (CIT) is a common complication of the treatment of non-hematologic malignancies. Many patient-related variables (e.g., age, tumor type, number of prior chemotherapy cycles, amount of bone marrow tumor involvement) determine the extent of CIT. CIT is related to the type and dose of chemotherapy, with regimens containing gemcitabine, platinum, or temozolomide producing it most commonly. Bleeding and the need for platelet transfusions in CIT are rather uncommon except in patients with platelet counts below 25x10⁹/L in whom bleeding rates increase significantly and platelet transfusions are the only treatment. Nonetheless, platelet counts below 70x10⁹/L present a challenge. In patients with such counts, it is important to exclude other causes of thrombocytopenia (medications, infection, thrombotic microangiopathy, post-transfusion purpura, coagulopathy and immune thrombocytopenia). If these are not present, the common approach is to reduce chemotherapy dose intensity or switch to other agents. Unfortunately decreasing relative dose intensity is associated with reduced tumor response and remission rates. Thrombopoietic growth factors (recombinant human thrombopoietin, pegylated human megakaryocyte growth and development factor, romiplostim, eltrombopag, avatrombopag and hetrombopag) improve pretreatment and nadir platelet counts, reduce the need for platelet transfusions, and enable chemotherapy dose intensity to be maintained. National Comprehensive Cancer Network guidelines permit their use but their widespread adoption awaits adequate phase III randomized, placebo-controlled studies demonstrating maintenance of relative dose intensity, reduction of platelet transfusions and bleeding, and possibly improved survival. Their potential appropriate use also depends on consensus by the oncology community as to what constitutes an appropriate pretreatment platelet count as well as identification of patient-related and treatment variables that might predict bleeding.

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.

Practice Guidelines of the Central European Hepatologic Collaboration (CEHC) on the Use of Thrombopoietin Receptor Agonists in Patients with Chronic Liver Disease Undergoing Invasive Procedures

BACKGROUND

Second-generation thrombopoietin receptor agonists (TPO-RAs) are emerging as the new standard for managing thrombocytopenia (TCP) in patients with chronic liver diseases (CLDs) undergoing scheduled procedures. However, practical guidance for their routine use in CLD patients undergoing specific invasive procedures is lacking.

METHODS

These practice guidelines were developed by the Initiative Group for Central European Hepatologic Collaboration (CEHC), composed of nine hepatologist/gastroenterologist experts from Central Europe. Using an adapted Delphi process, the CEHC group selected ten invasive procedures most relevant to the hepatology/gastroenterology setting in the region. Consensus recommendations for each invasive procedure are reported as a final percentage of expert panel responses.

RESULTS

A consensus was agreed that TPO-RAs should be considered for raising platelet count in CLD patients undergoing scheduled abdominal surgery, high-bleeding risk dentistry, endoscopic polypectomy, endoscopic variceal ligation, liver biopsy, liver surgery, liver transplantation and percutaneous ablation, but it was also agreed that they are less beneficial or not necessary for endoscopy without intervention and paracentesis.

CONCLUSIONS

Using a modified Delphi method, experts reached an agreement for TCP management in CLD patients undergoing ten invasive procedures. These practice guidelines may help with decision making and patient management in areas where clinical evidence is absent or limited.

Ultrasonography in the diagnosis of complications in patients with portal hypertension

This review focuses on ultrasonography (US) to diagnose patients with complications in portal hypertension. Clinicians first use US to evaluate patients with suspected portal hypertension, because US is quick, simple, and radiation free. US is necessary for grading and performing paracentesis for ascites. Doppler US-based detection of reverse splanchnic vein flow or the presence of a spontaneous portosystemic shunt is highly specific in patients with cirrhosis. Since it is important to estimate spleen size in patients with portal hypertension, spleen size is usually measured by US. Spleen volume can be more accurately measured with 3D-US. Estimation of viable residual splenic volume after partial splenic embolization should be limited to cases with total splenic volume less than 1000 ml. Portal vein thrombosis is often detected during the US examination performed when symptoms first appear or during the follow-up. Two-dimensional transthoracic echocardiography is an excellent noninvasive screening test in patients with pulmonary portal hypertension who can undergo it. By measuring the maximum and minimum diastolic blood flow velocities in the renal arteries using renal color Doppler US, the pulsatility index (PI) and resistive index (RI) can be calculated. The PI and RI in cirrhotic patients were significantly higher than those in healthy subjects and patients with chronic hepatitis, and showed a significant positive correlation with the Child-Pugh Score. In conclusion, US is an essential tool for the diagnosis and treatment of patients with portal hypertension.

Possible roles of platelets in liver transplantation: regeneration and cancer recurrence

When tissue injury results in breakage, platelets are not only involved in plug formation and wound sealing, but they also play an important role throughout the tissue recovery process. Specifically, platelets accumulate at the site of injury and release a large number of biologically active mediators at injury sites, which initiate or modulate damaged tissue regeneration. Moreover, extensive experimental evidence has elucidated the involvement of platelets in tumor growth and metastasis. As such, this mini-review aimed to highlight the relatively lesser known functions of platelets.

Efficiently Restored Thrombopoietin Production by Ashwell-Morell Receptor and IL-6R Induced Janus Kinase 2/Signal Transducer and Activator of Transcription Signaling Early After Partial Hepatectomy

BACKGROUND AND AIMS

Thrombocytopenia has been described in most patients with acute and chronic liver failure. Decreased platelet production and decreased half-life of platelets might be a consequence of low levels of thrombopoietin (TPO) in these patients. Platelet production is tightly regulated to avoid bleeding complications after vessel injury and can be enhanced under elevated platelet destruction as observed in liver disease. Thrombopoietin (TPO) is the primary regulator of platelet biogenesis and supports proliferation and differentiation of megakaryocytes.

APPROACH AND RESULTS

Recent work provided evidence for the control of TPO mRNA expression in liver and bone marrow (BM) by scanning circulating platelets. The Ashwell-Morell receptor (AMR) was identified to bind desialylated platelets to regulate hepatic thrombopoietin (TPO) production by Janus kinase (JAK2)/signal transducer and activator of transcription (STAT3) activation. Two-thirds partial hepatectomy (PHx) was performed in mice. Platelet activation and clearance by AMR/JAK2/STAT3 signaling and TPO production were analyzed at different time points after PHx. Here, we demonstrate that PHx in mice led to thrombocytopenia and platelet activation defects leading to bleeding complications, but unaltered arterial thrombosis, in these mice. Platelet counts were rapidly restored by up-regulation and crosstalk of the AMR and the IL-6 receptor (IL-6R) to induce JAK2-STAT3-TPO activation in the liver, accompanied by an increased number of megakaryocytes in spleen and BM before liver was completely regenerated.

CONCLUSIONS

The AMR/IL-6R-STAT3-TPO signaling pathway is an acute-phase response to liver injury to reconstitute hemostasis. Bleeding complications were attributable to thrombocytopenia and platelet defects induced by elevated PGI₂ , NO, and bile acid plasma levels early after PHx that might also be causative for the high mortality in patients with liver disease.

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.

Thrombocytopenia and Hemostatic Changes in Acute and Chronic Liver Disease: Pathophysiology, Clinical and Laboratory Features, and Management

Thrombocytopenia, defined as a platelet count <150,000/μL, is the most common complication of advanced liver disease or cirrhosis with an incidence of up to 75%. A decrease in platelet count can be the first presenting sign and tends to be proportionally related to the severity of hepatic failure. The pathophysiology of thrombocytopenia in liver disease is multifactorial, including (i) splenomegaly and subsequently increased splenic sequestration of circulating platelets, (ii) reduced hepatic synthesis of thrombopoietin with missing stimulation both of megakaryocytopoiesis and thrombocytopoiesis, resulting in diminished platelet production and release from the bone marrow, and (iii) increased platelet destruction or consumption. Among these pathologies, the decrease in thrombopoietin synthesis has been identified as a central mechanism. Two newly licensed oral thrombopoietin mimetics/receptor agonists, avatrombopag and lusutrombopag, are now available for targeted treatment of thrombocytopenia in patients with advanced liver disease, who are undergoing invasive procedures. This review summarizes recent advances in the understanding of defective but at low level rebalanced hemostasis in stable cirrhosis, discusses clinical consequences and persistent controversial issues related to the inherent bleeding risk, and is focused on a risk-adapted management of thrombocytopenia in patients with chronic liver disease, including a restrictive transfusion regimen.

The role and mechanism of miR-557 in inhibiting the differentiation and maturation of megakaryocytes in immune thrombocytopenia

Specific miRNA in immune thrombocytopenia (ITP) was screened to explore its intervention effects and mechanisms in ITP. MTT assay and CFSE staining were used to detect the effects of gradient concentrations of thrombopoietin (TPO) on cell proliferation. Expressions of differentially expressed miRNAs were analysed via qRT-PCR in TPO-induced megakaryocytes and ITP plasma. Effects of miR-557 on cell physiological functions were examined by MTT and flow cytometry. Expressions of miR-557, apoptosis-associated genes and Akt/ERK pathways were detected by qRT-PCR and Western blot as needed. Multinucleation of TPO-induced megakaryocytes was determined by megakaryocyte colonies. The toe skin and intestinal bleeding of the ITP rat model were observed and evaluated. Effects of miR-557 on the numbers of platelets, megakaryocytes, and peripheral blood platelets and the expressions of CD4⁺ T cells, Treg cells, TGF-β, IL-6 and miR-557 in the ITP rats were detected by Giemsa staining, flow cytometry, ELISA and qRT-PCR. MiR-557 was identified as an specific miRNA associated with both ITP and TPO treatment. MiR-557 inhibitor enhanced the physiological functions of TPO-induced megakaryocytes, while miR-557 mimic had the opposite effect. At the molecular level, the expressions of miR-557, cleaved Caspase-3 and Bax were further silenced by inhibitor, on the contrary, the expressions of bcl-2, p-Akt and p-ERK were upregulated. Animal experiments showed that, miR-557 inhibitor increased the numbers of platelets and megakaryocytes, and improved the symptoms of ITP model rats. Our results indicated that miR-557 inhibitor improved ITP by regulating apoptosis-related genes and cellular immunity and activating the Akt/ERK pathway.

Thrombopoietin Promotes Cell Proliferation and Attenuates Apoptosis of Aplastic Anemia Serum-Treated 32D Cells via Activating STAT3/STAT5 Signaling Pathway and Modulating Apoptosis-Related Mediators

The present study aimed to investigate the effect and possible mechanism of recombinant human thrombopoietin (rhTPO) on mouse 32D cells (a mouse myeloid progenitor cell line) treated with serum from patients with aplastic anemia and to elucidate the potential mechanism of rhTPO in the treatment of aplastic anemia. After treatment with aplastic anemia serum, the apoptotic rate of 32D cells was increased and the proliferation of 32D cells was significantly inhibited. rhTPO reduced the apoptotic rate and promoted the proliferation of 32D cells, while rhTPO failed to restore the cell proliferation of 32D cells from aplastic anemia serum group to the normal level as compared to that from the normal serum group. The phosphorylation level of STAT3 protein was higher, and the phosphorylation level of STAT5 protein was lower in 32D cells from aplastic anemia serum group than that in normal serum group. After rhTPO treatment, the phosphorylation level of STAT3 protein in aplastic anemia serum group was decreased and the phosphorylation level of STAT5 protein was increased. The expression levels of Survivin and Bcl-2 were significantly decreased in 32D cells from aplastic anemia serum group, which were significantly increased after rhTPO treatment. The expression level of Bax protein in 32D cells from the normal serum group after rhTPO treatment was significantly decreased; while the mRNA expression level of Bax was not affected by rhTPO. The expression levels of Bax mRNA and protein were significantly up-regulated in 32D cells from aplastic anemia serum group, which was significantly decreased by rhTPO treatment. In conclusion, our results indicated that aplastic anemia serum impaired proliferative potential and enhanced apoptosis of 32D cells. Further mechanistic studies revealed that rhTPO promoted cell proliferation and attenuated apoptosis of aplastic anemia serum-treated 32D cells via activating STAT3/STAT5 signaling pathway and modulating apoptosis-related mediators.

Thrombocytopenia in Chronic Liver Disease: New Management Strategies

Thrombocytopenia is common in advanced liver disease, and such patients frequently need invasive procedures. Numerous mechanisms for thrombocytopenia exist, including splenic sequestration and reduction of levels of the platelet growth factor thrombopoietin. Traditionally, platelet transfusions have been used to increase platelet counts before elective procedures, usually to a threshold of greater than or equal to 50,000/μL, but levels vary by provider, procedure, and specific patient. Recently, the thrombopoietin receptor agonists avatrombopag and lusutrombopag were studied and found efficacious for increasing platelet count in the outpatient setting for select patients with advanced liver disease who need a procedure.

Thrombocytopenia and Procedural Prophylaxis in the Era of Thrombopoietin Receptor Agonists

Thrombocytopenia is common in patients with advanced liver disease. These patients frequently require invasive diagnostic or therapeutic procedures in the setting of thrombocytopenia. A common platelet goal before such procedures is ≥50,000/μL, but target levels vary by provider and the procedure. Platelet transfusion has disadvantages, including safety and cost. No other short‐term options for ameliorating thrombocytopenia before procedures were available until the thrombopoietin receptor agonists were recently approved. Avatrombopag and lusutrombopag can be used in certain patients with thrombocytopenia due to advanced liver disease undergoing elective invasive procedures; these new agents are highly effective in carefully selected patients, and real world data of safety and efficacy are awaited.

TPO receptor agonists are an exciting new development that can raise platelet counts in liver patients with thrombocytopenia before elective procedures. We review the strategies to address peri‐procedure thrombocytopenia including data on the most recent trials involving TPO receptor agonists.

It's reticulated: the liver at the heart of atherosclerosis

Platelets play a critical role in both the initiation and progression of atherosclerosis, and even more so in the ensuing atherothrombotic complications. Low-dose aspirin remains the mainstay of antiplatelet therapy in high-risk patients by reducing the risk of myocardial ischemia, stroke or death due to cardiovascular disease. However, antiplatelet therapies lose their efficacy in people with diabetes mellitus, increasing the risk of future atherothrombotic events. The molecular mechanisms that promote platelet hyperactivity remain unclear but could be due to glycation-induced conformational changes of platelet membranes resulting in impaired aspirin entry or less-efficient acetylation/compensatory increase in COX-2 expression in newborn platelets. Emerging evidence from our laboratory and elsewhere suggest that enhanced platelet turnover (thrombopoiesis), particularly the production of immature reticulated platelets from the bone marrow, could contribute to atherosclerotic complications. We have identified a major role for neutrophil-derived S100A8/A9, a damage-associated molecular pattern, in driving reticulated thrombopoiesis by directly interacting with its receptors on Kupffer cells in the liver. In this review, we discuss the role of hepatic inflammation in driving reticulated platelet production and suggest potential targets to control their production, improve efficacy of current antiplatelet therapies and reduce the risk of atherothrombotic complications.

Risk of posttransplant hepatocellular carcinoma recurrence is greater in recipients with higher platelet counts in living donor liver transplantation

Platelets interact with tumor cells and promote metastasis. The importance of platelets in posttransplant hepatocellular carcinoma (HCC) recurrence is unclear. Thus, we aimed to evaluate the association between preoperative platelet count (PLT) and HCC recurrence after living donor liver transplantation. Of 359 recipients of livers from living donors for HCC, 209 of 240 patients who had preoperative PLT ≤75 × 10⁹ /L were matched with 97 of 119 patients who had preoperative PLT >75 × 10⁹ /L using propensity score matching, with an unfixed matching ratio based on factors such as tumor biology. The cutoff value of 75 × 10⁹ /L was set based on optimum stratification analysis. Survival analysis was performed with death as a competing risk event. The primary outcome was overall HCC recurrence. The median follow-up time was 59 months. Before matching, recurrence probability at 1, 2, and 5 years after transplantation was 4.7%, 9.2%, and 11.3% for the low platelet group and 14.5%, 23.0%, and 30.5% for the high platelet group. Recurrence risk was significantly greater in the high platelet group in both univariate (hazard ratio [HR] = 3.09; 95% confidence interval [CI], 1.86-5.14; P < 0.001) and multivariate analyses (HR = 2.10; 95% CI, 1.23-3.60; P =  0.007). In the matched analysis, recurrence risk was also greater in the high platelet group in both univariate (HR = 2.33; 95% CI, 1.36-4.01; P =  0.002) and multivariate analyses (HR = 1.90; 95% CI, 1.02-3.54; P =  0.04). Preoperative PLT had no interaction with the Milan criteria, alpha-fetoprotein level, Edmonson grade, microvascular invasion, or intrahepatic metastasis. Incorporation of preoperative PLT into the Milan criteria significantly improved predictive power. Inflammation-based scores including neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and the inflammation-based index did not show superiority to preoperative PLT in predicting HCC recurrence. In conclusion, preoperative PLT appears to be an important host factor affecting HCC recurrence after living donor liver transplantation. Liver Transplantation 24 44-55 2018 AASLD.

Utility of Doppler ultrasonography for predicting improvement of platelet count after transjugular intrahepatic portosystemic shunt

OBJECTIVE

Portal pressure gradient (PPG) after transjugular intrahepatic portosystemic shunt (TIPS) <12 mmHg has been reported as the only factor predictive of increase in platelet count. As flow velocities measured on Doppler ultrasound are related to pressure gradient based on the Bernoulli equation, we used this parameter to predict increased platelet count after TIPS placement.

METHODS

A total of 161 consecutive patients who underwent TIPS placement entered this retrospective study. The platelet count was measured before, one week after and one month after TIPS placement. Clinically significant thrombocytopenia was defined as platelet count ≤100 000. Pre- and post-TIPS PPGs were measured. The velocity of blood flow in the proximal, mid and distal TIPS stent was measured using Doppler ultrasound, and the difference in the highest and lowest measured velocity was entitled flow velocity gradient (FVG), which was considered normal when ≤100 cm/s.

RESULTS

In 121 patients with pre-TIPS thrombocytopenia, the mean platelet count one week and one month after TIPS placement increased 25.7 x 103 and 35.0 x 103 in 90 patients with PPG≤12 mmHg (P=0.028 and P=0.015), while there was no significant change in platelet count in patients with a PPG >12 mmHg (P=0.098 and P=0.075). Platelets increased significantly when FVG≤ 100 cm/s (n=95) vs FVG >100 cm/s (n=26) one week (37.0x103 vs 11.0x103; P =  0.005 vs 0.07) and one month after TIPS placement (17.0x103 vs 5.2x103; P =  0.01 vs 0.21).

CONCLUSION

FVG >100 cm/s is not associated with increase in post-TIPS platelet count. On the other hand, findings suggestive of proper TIPS function (FVG ≤100 cm/s and PPG≤ 12 mmHg) predict a significant increase in post-TIPS platelet count.

Thrombocytopenia in chronic liver disease

Thrombocytopenia is a common haematological disorder in patients with chronic liver disease. It is multifactorial and severity of liver disease is the most influential factor. As a result of the increased risk of bleeding, thrombocytopenia may impact upon medical procedures, such as surgery or liver biopsy. The pathophysiology of thrombocytopenia in chronic liver disease has long been associated with the hypothesis of hypersplenism, where portal hypertension causes pooling and sequestration of all corpuscular elements of the blood, predominantly thrombocytes, in the enlarged and congested spleen. Other mechanisms of importance include bone marrow suppression by toxic substances, such as alcohol or viral infection, and immunological removal of platelets from the circulation. However, insufficient platelet recovery after relief of portal hypertension by shunt procedures or minor and transient recovery after splenic artery embolization have caused many to question the importance and relative contribution of this mechanism to thrombocytopenia. The discovery of the cytokine thrombopoietin has led to the elucidation of a central mechanism. Thrombopoietin is predominantly produced by the liver and is reduced when liver cell mass is severely damaged. This leads to reduced thrombopoiesis in the bone marrow and consequently to thrombocytopenia in the peripheral blood of patients with advanced-stage liver disease. Restoration of adequate thrombopoietin production post-liver transplantation leads to prompt restoration of platelet production. A number of new treatments that substitute thrombopoietin activity are available or in development.

Association of Nonalcoholic Fatty Liver Disease and Venous Thromboembolism in Women With Endometrial Cancer

OBJECTIVE

Recent studies have demonstrated that surgical menopause results in a significantly increased risk of nonalcoholic fatty liver disease (NAFLD) in women with endometrial cancer. In addition, venous thromboembolism (VTE) is known to be one of the major prognostic factors for decreased survival in endometrial cancer. Given the fact that coagulation factors are produced in the liver, the correlation between NAFLD and VTE was examined in endometrial cancer.

METHODS

A retrospective study was conducted to examine patients with endometrial cancer who underwent surgical staging including oophorectomy between 2000 and 2013 (n = 714). Cumulative risk of VTE was examined based on the NAFLD status. A Cox proportional hazard regression model was used to determine the independent risk predictors of VTE.

RESULTS

Venous thromboembolism and NAFLD were seen in 57 (8.0%) and 181 (25.4%) cases, respectively. Two-year cumulative risks of VTE and NAFLD were 7.9% and 19.3%, respectively. In univariate analysis, VTE was significantly associated with decreased disease-free survival (2-year rate, 43.6% vs 91.4%, P < .001) and overall survival (65.8% vs 96.8%, P < .001), whereas NAFLD was associated with decreased risk of VTE (1.7% vs 10.4%, P < .001). In multivariate analysis controlling for clinicopathological factors, NAFLD remained an independent predictor of decreased risk of VTE (hazard ratio [HR]: 0.24, 95% confidence interval [CI]: 0.07-0.79, P = .02). Thrombocytosis (HR: 2.30, 95% CI: 1.22-4.35, P = .01), cancer antigen 125 ≥ 35 (HR: 3.81, 95% CI: 1.78-8.17, P < .001), and recurrent disease (HR: 4.57, 95% CI: 1.97-10.6, P < .001) remained as independent predictors of increased risk of VTE.

CONCLUSION

Our results suggest that NAFLD may be associated with decreased VTE risk in women with endometrial cancer.

Immature platelet fraction values predict recovery of platelet counts following liver transplantation

BACKGROUND

Thrombocytopenia after orthotopic liver transplantation (OLT) is a well-recognized and prevalent early postoperative complication. In the current study, we assessed the clinical utility of the immature platelet fraction (expressed as a percent of total platelets, IPF %) to predict platelet count recovery following OLT.

METHODS

We analyzed the changes in peripheral platelet counts, IPF values, and liver function before OLT, and 21 days after transplantation in 30 patients with liver cirrhosis. All patients were followed up for at least six months.

RESULTS

The nadir in the peripheral platelet counts most commonly occurred on the 5th day after post-transplant. Platelets counts gradually rose again to exceed pre-transplant levels by the 3rd to 4th day after the IPF % reached its peak.

CONCLUSION

The IPF % increased prior to the elevation of platelet counts in patients with OLT suggesting that the IPF % may reflect production of platelets. These findings suggest IPF% could be useful as a predictor of platelet recovery in patients with OLT.

Immediate Postoperative Low Platelet Counts After Living Donor Liver Transplantation Predict Early Allograft Dysfunction

To investigate whether the platelets can improve liver function by mediating liver regeneration. Using a retrospective cohort with 234 consecutive adult-to-adult living donor liver transplantation recipients, we have discussed the relationship between immediate postoperative platelet count and outcome. Patients have been stratified into Low Platelet Group (106 patients) with platelet ≤68 × 10/L and High Platelet Group (128 patients) with platelet >68 × 10/L.Low Platelet Group has a higher rate of preoperative thrombocytopenia (90.6% vs. 32.8%, P<0.001), higher model for end-stage liver disease score (15 vs. 11, P<0.001), cirrhosis (86.8% vs. 76.6%, P=0.046), hepatorenal syndrome (18.2% vs. 4.0%, P=0.005) and fulminant hepatic failure (26.4% vs. 7.8%, P<0.001). The packed red blood cells transfusion (7.5 vs. 5, P = 0.023) and plasma transfusion (1275 mL vs. 800 mL, P=0.001) are more in patients with low platelet count. Low Platelet Group has a higher early allograft dysfunction (EAD) (22.6% vs. 7.0%, P=0.001) and severe complications (22.6% vs. 10.9%, P = 0.016). The 90-day mortality between the 2 groups is similar. The multivariate analysis has found that postoperative platelet ≤68 × 10/L is an independent risk factor for EAD.Platelet maybe influences the functional status of the liver by promoting graft regeneration after liver transplantation.

Recombinant human thrombopoietin treatment promotes hematopoiesis recovery in patients with severe aplastic anemia receiving immunosuppressive therapy

Objective. To assess the effectiveness of recombinant human thrombopoietin (rhTPO) in severe aplastic anemia (SAA) patients receiving immunosuppressive therapy (IST). Methods. Eighty-eight SAA patients receiving IST from January 2007 to December 2012 were included in this retrospective analysis. Of these, 40 subjects received rhTPO treatment (15000 U, subcutaneously, three times a week). rhTPO treatment was discontinued when the platelet count returned to normal range. Hematologic response, bone marrow megakaryocyte recovery, and time to transfusion independence were compared. Results. Hematologic response was achieved in 42.5%, 62.5%, and 67.5% of patients receiving rhTPO and 22.9%, 41.6%, and 47.9% of patients not receiving rhTPO at 3, 6, and 9 months after treatment, respectively (P = 0.0665, P = 0.0579, and P = 0.0847, resp.). Subjects receiving rhTPO presented an elevated number of megakaryocytes at 3, 6, and 9 months when compared with those without treatment (P = 0.025, P = 0.021, and P = 0.011, resp.). The time to platelet and red blood cell transfusion independence was shorter in patients who received rhTPO than in those without rhTPO treatment. Overall survival rate presented no differences between the two groups. Conclusion. rhTPO could improve hematologic response and promote bone marrow recovery in SAA patients receiving IST.

Epidemiology, diagnosis and early patient management of esophagogastric hemorrhage

Acute variceal bleeding (AVB) is a potentially life-threatening complication of cirrhosis and portal hypertension. Combination therapy with vasoactive drugs and endoscopic variceal ligation is the first-line treatment in the management of AVB after adequate hemodynamic resuscitation. Short-term antibiotic prophylaxis, early resuscitation, early use of lactulose for prevention of hepatic encephalopathy, targeting of conservative goals for blood transfusion, and application of early transjugular intrahepatic portosystemic shunts in patients with AVB have further improved the prognosis of AVB. This article discusses the epidemiology, diagnosis, and nonendoscopic management of AVB.

Thrombocytopenia, Platelet Transfusion, and Outcome Following Liver Transplantation

Thrombocytopenia affects patients undergoing liver transplantation. Intraoperative platelet transfusion has been shown to independently influence survival after liver transplantation at 1 and 5 years. We examined the impact of thrombocytopenia and intraoperative platelet transfusion on short-term graft and overall survival after orthotopic liver transplantation (OLT). A total of 399 patients undergoing first OLT were studied. Graft and overall survival in patients with different degrees of thrombocytopenia and with or without intraoperative platelet transfusion were described. The degree of thrombocytopenia prior to OLT did not affect graft or overall survival after transplant. However, graft survival in patients receiving platelets was significantly reduced at 1 year (P= .023) but not at 90 days (P= .093). Overall survival was significantly reduced at both 90 days (P= .040) and 1 year (P= .037) in patients receiving platelets. We conclude that a consistently lower graft and overall survival were observed in patients receiving intraoperative platelet transfusion.

Genetic variants in human leukocyte antigen-DP influence both hepatitis C virus persistence and hepatitis C virus F protein generation in the Chinese Han population

Chronic hepatitis C is a serious liver disease that often results in cirrhosis or hepatocellular carcinoma. The aim of this study was to assess the association of human leukocyte antigen-DP (HLA-DP) variants with risk of chronic hepatitis C virus (HCV) or anti-F antibody generation. We selected two single nucleotide polymorphisms (SNPs) in a region including HLA-DPA1 (rs3077) and HLA-DPB1 (rs9277534) and genotyped SNPs in 702 cases and 342 healthy controls from the Chinese population using TaqMan SNP genotyping assay. Moreover, the exon 2 of the HLA-DPA1 and HLA-DPB1 genes were amplified and determined by sequencing-based typing (SBT). The results showed that rs3077 significantly increased the risk of chronic HCV infection in additive models and dominant models (odds ratio (OR) = 1.32 and 1.53). The rs3077 also contributed to decrease the risk of anti-F antibody generation in additive models and dominant models (OR = 0.46 and 0.56). Subsequent analyses revealed the risk haplotypes (DPA1*0103-DPB1*0501 and DPA1*0103-DPB1*0201) and protective haplotypes (DPA1*0202-DPB1*0501 and DPA1*0202-DPB1*0202) to chronic HCV infection. Moreover, we also found that the haplotype of DPA1*0103-DPB1*0201 and DPA1*0202-DPB1*0202 were associated with the anti-F antibody generation. Our findings show that genetic variants in HLA-DP gene are associated with chronic HCV infection and anti-F antibody generation.

Abnormal platelet kinetics are detected before the occurrence of thrombocytopaenia in HBV-related liver disease

BACKGROUND & AIMS

Thrombocytopaenia is a frequent feature in patients with HBV-related liver disease. Its underlying mechanism is not fully understood. Multiple factors might contribute to the development of thrombocytopaenia. In this study, we investigated the reticulated platelets (RP), glycocalicin (GC), serum thrombopoietin (TPO) and platelet glycoprotein (GP) in different stages of the disease.

METHODS

One hundred and fourteen patients with HBV-related liver disease (30 with chronic hepatitis B (CHB), 20 patients in Child A without thrombocytopaenia, 19 patients in Child A with thrombocytopaenia, 45 in Child B/C with thrombocytopaenia) and 25 normal controls (NC) were enrolled. Liver cirrhosis (LC) was classified according to modified Child-Turcotte-Pugh (CTP) score. Serum TPO levels and GC were measured by ELISA. RP and platelet glycoprotein (GP) expression were detected by flow cytometry.

RESULTS

The TPO levels of patients with LC were significantly lower than that of controls, even in patients of Child A without thrombocytopaenia group. Serum TPO level was positively correlated (r = 0.65, p < 0.01) with serum albumin in Child B/C group. Both the RP percentages and the glycocalicin index (GCI) levels were significantly higher in patients groups including CHB and Child A without thrombocytopaenia than that of normal controls. A negative correlation existed in HBV DNA copies and the GPs% in patients with CHB and Child A without thrombocytopaenia.

CONCLUSION

Abnormal platelet production, destruction and platelet-specific glycoproteins levels were detected before the occurrence of thrombocytopaenia in HBV-related liver disease, indicating that multiple mechanisms might play roles in thrombocytopaenia in HBV-infected patients.

Milestones in understanding platelet production: a historical overview

The discovery of thrombopoietin (TPO, also termed THPO) in 1994 was a major achievement in understanding the regulation of platelet production. In prior decades, physiological studies had demonstrated that platelets were produced from bone marrow megakaryocytes and that the megakaryocytes responded to thrombocytopenia by increasing their number, size and DNA ploidy. In 1958, it was proposed that a 'thrombopoietin' must exist that regulated this interaction between the circulating platelet mass and the bone marrow megakaryocytes. After over three decades of effort, TPO was finally purified by five independent laboratories. TPO stimulated megakaryocyte colony-forming cell growth and increased the number, size and ploidy of megakaryocytes. When the genes for TPO or TPO receptor were eliminated in mice, megakaryocytes grew and platelets were made, but at 15% of their normal number. A first generation of recombinant human (rh) TPO molecules [rhTPO and pegylated recombinant human megakaryocyte growth and development factor (PEG-rhMGDF)] rapidly entered clinical trials in 1995 and increased platelet counts in humans undergoing non-myeloablative chemotherapy but not in those undergoing stem cell transplantation. Antibodies developed against PEG-rhMGDF and development of these recombinant thrombopoietins ended. A second generation of TPO receptor agonists (romiplostim and eltrombopag) was then developed. Neither of these TPO receptor agonists demonstrated any significant untoward effects and both are now licensed in many countries for the treatment of immune thrombocytopenia. This review describes the significant experiments that have surrounded the discovery of TPO and its clinical development.

Thrombopoietin levels in patients with disorders of platelet production: diagnostic potential and utility in predicting response to TPO receptor agonists

Thrombopoietin (TPO) is the major regulator of megakaryopoiesis. Measurement of serum TPO levels may help distinguish between various causes of thrombocytopenia and predict treatment response to TPO receptor agonists. Serum TPO levels from 118 healthy volunteers and 88 patients with abnormal platelet counts were measured using a quantitative ELISA assay. The mean (range) TPO level in healthy volunteers was 39 (7-99) pg/mL. TPO values were correlated with the patient's diagnosis, platelet count, and response to TPO receptor agonists. 88 patients with history of consumptive thrombocytopenia (39) or hypoproliferative thrombocytopenia (49) were analyzed. Median (interquartile range) TPO level for consumptive thrombocytopenia patients was 63 (48-98) pg/mL with a corresponding median (interquartile range) platelet count of 73 (28-146) × 10(9) /L. In contrast, hypoproliferative thrombocytopenia patients had platelet counts [59 (30-117) × 10(9) /L] comparable with consumptive thrombocytopenia patients, but significantly higher serum TPO levels [706 (358-1546) pg/mL, P < 0.0001]. Analysis of 21 ITP patients treated with TPO receptor agonists demonstrated that a TPO level >95 pg/mL was associated with lack of clinical response (P < 0.002). TPO levels may have diagnostic utility in discriminating between patients with hypoproliferative and consumptive thrombocytopenia. Elevated TPO levels in ITP patients may predict a poor clinical response to treatment with TPO receptor agonists.

Incidence of heparin-induced thrombocytopenia type II and postoperative recovery of platelet count in liver graft recipients: a retrospective cohort analysis

BACKGROUND

Thrombocytopenia in patients with end-stage liver disease is a common disorder caused mainly by portal hypertension, low levels of thrombopoetin, and endotoxemia. The impact of immune-mediated heparin-induced thrombocytopenia type II (HIT type II) as a cause of thrombocytopenia after liver transplantation is not yet understood, with few literature citations reporting contradictory results. The aim of our study was to demonstrate the perioperative course of thrombocytopenia after liver transplantation and determine the occurrence of clinical HIT type II.

METHOD

We retrospectively evaluated the medical records of 205 consecutive adult patients who underwent full-size liver transplantation between January 2006 and December 2010 due to end-stage or malignant liver disease. Preoperative platelet count, postoperative course of platelets, and clinical signs of HIT type II were analyzed.

RESULTS

A total of 155 (75.6%) of 205 patients had thrombocytopenia before transplantation, significantly influenced by Model of End-Stage Liver Disease score and liver cirrhosis. The platelet count exceeded 100,000/μL in most of the patients (n = 193) at a medium of 7 d. Regarding HIT II, there were four (1.95%) patients with a background of HIT type II.

CONCLUSIONS

The incidence of HIT in patients with end-stage hepatic failure is, with about 1.95%, rare. For further reduction of HIT type II, the use of intravenous heparin should be avoided and the prophylactic anticoagulation should be performed with low-molecular-weight heparin after normalization of platelet count.

Thrombocytopenia in patients with hepatitis B virus-related chronic hepatitis: evaluation of the immature platelet fraction

The immature platelet fraction (IPF) measures the number of reticulated platelets in peripheral blood, and can be used to help determine if thrombocytopenia is secondary to low-platelet production or increased platelet turnover. The aim of this study was to determine whether abnormalities in the IPF were associated with thrombocytopenia in patients with hepatitis B virus-related chronic hepatitis (CHB). One hundred fifty-six patients with chronic hepatitis B, including 80 thrombocytopenia, 76 without thrombocytopenia, and 48 healthy controls were enrolled in the study. The IPF percentages (IPF%) were measured using a XE-2100 multiparameter automatic hematology analyzer. We demonstrated that in the thrombocytopenic group, the IPF% was significantly increased compared with that in healthy controls and the non-thrombocytopenic group (both p < 0.001). Multivariate analysis demonstrated that IPF%, splenomegaly, and the model for end-stage liver disease score were independent predictors for thrombocytopenia (both p < 0.001). High IPF% during the course of thrombocytopenia suggests that platelet destruction/sequestration due to hypersplenism is a major factor contributing to thrombocytopenia in patients with CHB.

Long-term dynamics of hematological data and spleen volume in cirrhotic patients after liver transplantation-various dynamics depending on etiology

Background

Hypersplenism is a common complication in cirrhotic patients, and liver transplantation would be one of the effective treatments. However, detailed dynamics, especially over a long term, are not fully understood. We investigated the long-term dynamics of hematological data and spleen volumes, as well as their correlation in cirrhotic patients who underwent liver transplantation.

Patients and methods

We studied 53 cirrhotic patients who underwent liver transplantation at our institute and followed for more than 1 year. Hematological data were collected from medical records, while spleen volumes were determined by CT volumetry at 0, 1, 3, 6, 12, 24, 36, 48, 60 postoperative months (POM).

Results

(1) Platelet (Plt) and hemoglobin (Hb) levels were gradually increased up to 18 and 10 POM, respectively, in contrast with white blood cells (WBC), which remained mostly unchanged from pretransplantation levels. (2) Spleen volume was sharply decreased in the first POM, then showed a slower but steady decline up to 48 POM. (3) Spleen volume was significantly correlated with hematological data, though the levels were generally weak (Plt: r = 0.433, p < 0.001; Hb: r = 0.233, p < 0.001; WBC: r = 0.217, p = 0.001). (4) Spleen volume was strongly correlated with all hematological parameters in HBV patients (Plt: r = 0.617, p < 0.0001; Hb: r = 0.401, p < 0.001; WBC: r = 0.387, p < 0.001), in contrast with that in other etiologies, which had generally weak correlations though some were statistically significant.

Conclusions

We investigated the long-term dynamics of hematological data and spleen volume in cirrhotic patients after liver transplantation. Unique dynamics and correlations between them were found among the different etiologies investigated.

The biology of thrombopoietin and thrombopoietin receptor agonists

Thrombopoietin (TPO) is the major physiological regulator of platelet production. TPO binds the TPO receptor, activates JAK and STAT pathways, thus stimulating megakaryocyte growth and platelet production. There is no "sensor" of the platelet count; rather TPO is produced in the liver at a constant rate and cleared by TPO receptors on platelets. TPO levels are inversely proportional to the rate of platelet production. Early recombinant TPO molecules were potent stimulators of platelet production and increased platelets in patients with immune thrombocytopenia, chemotherapy-induced thrombocytopenia, myelodysplastic syndromes and platelet apheresis donors. Neutralizing antibodies formed against one recombinant protein and ended their development. A second generation of TPO receptor agonists, romiplostim and eltrombopag, has been developed. Romiplostim is an IgG heavy chain into which four TPO agonist peptides have been inserted. Eltrombopag is an oral small molecule. These activate the TPO receptor by different mechanisms to increase megakaryocyte growth and platelet production. After administration of either to healthy volunteers, there is a delay of 5 days before the platelet count rises and subsequently reaches a peak after 12-14 days. Both have been highly effective in treating ITP and hepatitis C thrombocytopenia. Studies in a wide variety of other thrombocytopenic conditions are underway.

Prothrombin complex concentrate in the reduction of blood loss during orthotopic liver transplantation: PROTON-trial

BACKGROUND

In patients with cirrhosis, the synthesis of coagulation factors can fall short, reflected by a prolonged prothrombin time. Although anticoagulants factors are decreased as well, blood loss during orthotopic liver transplantation can still be excessive. Blood loss during orthotopic liver transplantation is currently managed by transfusion of red blood cell concentrates, platelet concentrates, fresh frozen plasma, and fibrinogen concentrate. Transfusion of these products may paradoxically result in an increased bleeding tendency due to aggravated portal hypertension. The hemostatic effect of these products may therefore be overshadowed by bleeding complications due to volume overload.In contrast to these transfusion products, prothrombin complex concentrate is a low-volume highly purified concentrate, containing the four vitamin K dependent coagulation factors. Previous studies have suggested that administration of prothrombin complex concentrate is an effective method to normalize a prolonged prothrombin time in patients with liver cirrhosis. We aim to investigate whether the pre-operative administration of prothrombin complex concentrate in patients undergoing liver transplantation for end-stage liver cirrhosis, is a safe and effective method to reduce perioperative blood loss and transfusion requirements.

METHODS/DESIGN

This is a double blind, multicenter, placebo-controlled randomized trial.Cirrhotic patients with a prolonged INR (≥1.5) undergoing liver transplantation will be randomized between placebo or prothrombin complex concentrate administration prior to surgery. Demographic, surgical and transfusion data will be recorded. The primary outcome of this study is RBC transfusion requirements.

DISCUSSION

Patients with advanced cirrhosis have reduced plasma levels of both pro- and anticoagulant coagulation proteins. Prothrombin complex concentrate is a low-volume plasma product that contains both procoagulant and anticoagulant proteins and transfusion will not affect the volume status prior to the surgical procedure. We hypothesize that administration of prothrombin complex concentrate will result in a reduction of perioperative blood loss and transfusion requirements. Theoretically, the administration of prothrombin complex concentrate may be associated with a higher risk of thromboembolic complications. Therefore, thromboembolic complications are an important secondary endpoint and the occurrence of this type of complication will be closely monitored during the study.

TRIAL REGISTRATION

The trial is registered at http://www.trialregister.nl with number NTR3174. This registry is accepted by the ICMJE.

Eltrombopag in patients with chronic liver disease

INTRODUCTION

Thrombocytopenia may represent a barrier to optimal management of chronic liver disease patients undergoing invasive procedures, or who need to be treated with interferon-based antiviral therapy. Eltrombopag is a thrombopoietic drug that acts upon binding thrombopoietin receptor and stimulates megakaryocytopoiesis and platelet production.

AREAS COVERED

A summary of the preclinical studies and of studies carried out in patients with chronic liver disease with eltrombopag are presented in this paper. Data are based on abstracts from journal articles and international conferences found in a PubMed search of literature published up to November 2012.

EXPERT OPINION

Eltrombopag has shown to be capable of reducing the need for platelet transfusion in thrombocytopenic patients with advanced liver disease undergoing invasive procedures and help increase the sustained virological response rate to interferon-based antiviral therapy in patients with chronic hepatitis C who were poor candidates to treatment because of thrombocytopenia. In chronic liver disease patients, the possible benefits of eltrombopag administration should be accurately weighed against the adverse events profile of the drug due to possible concerns regarding the occurrence of thromboembolic events and the potential for decompensation of chronic liver disease.