Thrombopoietic cytokines and reversal of thrombocytopenia after liver transplantation

Thrombopoietic cytokines in patients with hepatitis C virus-associated immune thrombocytopenia

OBJECTIVES

Complex and multiple mechanisms are involved in the etiology of Hepatitis C virus-associated immune thrombocytopenia (HCV-ITP). Many hematopoietic growth factors affect the thrombopoiesis. The aim of this study was to clarify the interaction of the thrombopoietic factors in patients with HCV-ITP.

METHODS

We selected 33 patients with HCV-ITP and 17 normal individuals. We compare serum interleukin (IL)-3, IL-6, IL-11, thrombopoietin (Tpo), stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor (GM-CSF), tumour necrosis factor-α (TNFα), and spleen size between these two groups.

RESULTS

Our study shows that Tpo, IL-6, and TNFα significantly increased in patients with HCV-ITP compared to the normal population (Tpo:122.577 vs. 40.602; IL-6: 2.175 vs. 0.943; TNFα: 2.460 vs. 1.322). IL-11 was significantly lower in the HCV-ITP group (10.829 vs. 15.042). HCV-ITP patients had a higher spleen index (21.121 vs 13.498, P = 0.003). According to regression analysis and multiple linear regression analysis, only IL-11 had a significantly positive correlation with platelet count, while TNFα showed a negative correlation.

DISCUSSIONS

Tpo and IL-6 increased in patients with HCV-ITP, suggesting a positive feedback of low platelet count. TNFα-associated immune response is suspected to have an impact on low platelet count. IL-11 is assumed to directly affect thrombopoiesis.

CONCLUSIONS

This study is the most comprehensive study to evaluate the interaction between platelet count and the important thrombopoetic factors in patients with HCV-ITP. The thrombopoietic factors clearly play an important role in HCV-ITP.

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.

Thrombocytopenia, splenomegaly, and portal blood flow in patients who have undergone liver transplantation for cirrhosis

The platelet count (PC), the spleen size (SS), and the portal blood flow (PBF) have been independently studied in the perioperative period after orthotopic liver transplantation (OLT) for cirrhosis, but these parameters have not been described and analyzed in combination. We analyzed PC data and Doppler sonography measurements of SS and PBF from 125 adult patients before OLT and 1, 3, 6, 9, and 12 months after transplantation. A linear mixed model with fixed subject random intercepts was used. PCs increased significantly from 101.5 ± 68.5 × 10(9) /L before OLT to 162.4 ± 86 × 10(9) /L 1 month after OLT and remained stable for 1 year after the operation. PBF increased significantly from 619 ± 239 mL/minute before OLT to 1379 ± 491 mL/minute after OLT and remained stable during the first year. SS slowly decreased after OLT, but the decrease became significant only 9 months after the operation (13.8 ± 4.2 cm before OLT versus 11.7 ± 3.7 cm at 9 months, P < 0.05). The cirrhosis etiology did not influence the evolution of the parameters. With or without replication or interferon treatment before OLT, the hepatitis C group viruses did not influence PCs postoperatively. The evolution of SS was correlated to the evolution of PCs in the year after transplantation. In conclusion, PCs and PBF increase rapidly after OLT, whereas SS slowly decreases. The cirrhosis etiology does not influence the evolution of PCs. Thrombocytopenia and splenomegaly are 2 results of portal hypertension, but the rapid normalization of PBF does not completely or rapidly reverse these 2 phenomena.

Rifaximin improves thrombocytopenia in patients with alcoholic cirrhosis in association with reduction of endotoxaemia

BACKGROUND

Thrombocytopenia is a major haematological disorder of cirrhosis with unclear pathogenesis. Endotoxaemia resulting from intestinal bacterial overgrowth could reduce platelet counts directly or through cytokine release.

AIMS

To correlate endotoxaemia with platelet counts and study the effects of intestinal decontamination with rifaximin on thrombocytopenia in relation to changes in endotoxin and cytokine concentrations in patients with alcoholic cirrhosis.

METHODS

Platelet counts, plasma endotoxin levels and serum interleukin-1 (IL-1), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) levels were measured in 23 thrombocytopenic cirrhotic patients (platelet count<150 000/μl) before and after 4-week treatment with rifaximin 1200 mg/d (n = 13) or no treatment (n = 10) and at baseline in 10 cirrhotic patients without thrombocytopenia; spleen size was measured at baseline in all patients.

RESULTS

Endotoxin and IL-6 levels were significantly higher in patients with thrombocytopenia than in those without thrombocytopenia (2.76 ± 0.69 vs. 0.64 ± 0.09 EU/ml; P < 0.001 and 24.26 ± 3.38 vs. 2.66 ± 0.74 pg/ml; P = 0.001 respectively). Platelet counts were inversely correlated with endotoxin levels (r = -0.589; P = 0.003), Child-Pugh score (r = -0.625; P = 0.001), IL-6 levels (r = -0.464; P = 0.02) and spleen size (r = -0.455; P = 0.02) in patients with thrombocytopenia. Following rifaximin, platelet counts increased significantly (83 100 ± 9700 vs. 99 600 ± 11 200/μl; P = 0.006) in line with significant reductions in endotoxin (1.28 ± 0.41 vs. 2.54 ± 0.86 EU/ml; P = 0.005), IL-1 (3.1 ± 0.5 vs. 4.4 ± 1.2 pg/ml; P = 0.04), IL-6 (12.8 ± 2.5 vs. 21.1 ± 4.2 pg/ml; P = 0.01) and TNF-α (3.6 ± 1.3 vs. 5.8 ± 1.7; P = 0.02) levels. Platelet count changes were correlated with the changes in endotoxin (r = 0.573; P = 0.04), TNF-α (r = 0.554; P = 0.05) and IL-6 (r = 0.495; P = 0.07) levels.

CONCLUSIONS

Rifaximin improves cirrhosis-related thrombocytopenia and this could be related with the reduction of endotoxaemia.

Platelet production and destruction in liver cirrhosis

BACKGROUND & AIMS

Thrombocytopenia is common in liver cirrhosis (LC) but the mechanisms are not fully understood. The purpose of our work was to evaluate platelet kinetics in LC with different etiologies by examining platelet production and destruction.

METHODS

Ninety-one consecutive LC patients (36 HCV, 49 alcoholics, 15 HBV) were enrolled. As controls, 25 subjects with idiopathic thrombocytopenic purpura, 10 subjects with aplastic anemia, and 40 healthy blood donors were studied. Plasma thrombopoietin (TPO) was measured by ELISA. Reticulated platelets (RP) were determined using the Thiazole Orange method. Plasma glycocalicin (GC) was measured using monoclonal antibodies. Platelet associated and serum antiplatelet antibodies were detected by flow cytometry. B-cell monoclonality in PBMC was assessed by immunoglobulin fingerprinting.

RESULTS

Serum TPO was significantly lower in LC (29.9±18.1 pg/ml) compared to controls (82.3±47.6 pg/ml). The GC levels were higher in LC (any etiology) than in healthy cases. Conversely, the absolute levels of RP were lower in LC (any etiology) than in healthy controls. The platelet-associated and serum anti-platelet antibodies were higher in HCV+ LC compared to healthy subjects (p<0.0064), alcoholic LC (p<0.018), and HBV+ LC (p<0.0001). B-cell monoclonality was found in 27% of the HCV+LC, while it was not found in HBV+ or alcoholic LC.

CONCLUSIONS

Patients with LC present decreased plasma TPO, accelerated platelet turnover, and reduced platelet production. This indicates that LC thrombocytopenia is a multifactorial condition involving both increased platelet clearance and impaired thrombopoiesis.

Abnormal hematological indices in cirrhosis

Abnormalities in hematological indices are frequently encountered in cirrhosis. Multiple causes contribute to the occurrence of hematological abnormalities. Recent studies suggest that the presence of hematological cytopenias is associated with a poor prognosis in cirrhosis. The present article reviews the pathogenesis, incidence, prevalence, clinical significance and treatment of abnormal hematological indices in cirrhosis.

Severe thrombocytopenia before liver transplantation is associated with delayed recovery of thrombocytopenia regardless of donor type

AIM: To compare the recovery of thrombocytopenia and splenomegaly during long-term follow-up after liver transplantation in patients receiving a living donor transplant or a cadaveric donor transplant.

METHODS: This was a retrospective cohort study of 216 consecutive liver transplant patients who survived for > 6 mo after transplantation; 169 received a liver transplant from a living donor and 47 from a cadaveric donor. The platelet counts or spleen volumes were examined before transplant, 1, 6, and 12 mo after transplant, and then annually until 5 years after transplant.

RESULTS: The mean follow-up period was 49 mo (range, 21-66). Platelet counts increased continuously for 5 years after orthotopic liver transplant. The restoration of platelet counts after transplant was significantly slower in patients with severe pretransplant thrombocytopenia (< 50 000/μL) until 4 years after transplant (P = 0.005). Donor type did not significantly affect the recovery of platelet count and spleen volume in either patient group. In multivariate analysis, pretransplant severe thrombocytopenia (< 50 000/μL) was an independent factor associated with sustained thrombocytopenia (P < 0.001, odds ratio 6.314; confidence interval, 2.828-14.095). Thrombocytopenia reappeared after transplant in seven patients with portal flow disturbance near the anastomosis site.

CONCLUSION: Our study suggests that severe thrombocytopenia before transplant is closely associated with delayed recovery of platelet count after transplant and donor type did not affect the recovery of thrombocytopenia. The reappearance of thrombocytopenia after transplant should be considered a possible indicator of flow disturbance in the portal vein.

Review article: blood platelet number and function in chronic liver disease and cirrhosis

BACKGROUND

The liver plays a central role in coagulation and fibrinolysis but is also closely intertwined with the function and number of blood platelets.

AIM

To describe and integrate all literature concerning blood platelets and liver disease by performing a thorough literature research.

METHODS

A thorough literature research on 'blood platelets' and 'liver disease' was performed.

RESULTS

Thrombocytopenia is a marked feature of chronic liver disease and cirrhosis. Traditionally, this thrombocytopenia was attributed to passive platelet sequestration in the spleen. More recent insights suggest an increased platelet breakdown and to a lesser extent decreased platelet production plays a more important role. Besides the reduction in number, other studies suggest functional platelet defects. This platelet dysfunction is probably both intrinsic to the platelets and secondary to soluble plasma factors. It reflects not only a decrease in aggregability, but also an activation of the intrinsic inhibitory pathways. The net effect, finally, is a decreased platelet function in the various types of chronic liver diseases and cirrhosis. Finally, recent data suggest that platelets are not only affected by but can also contribute to the liver disease process, as for instance, in viral hepatitis and cholestatic liver disease.

CONCLUSION

Platelet research in liver disease is a growing area of investigation and could provide new pathophysiological insights.

Cytokines for the Treatment of Thrombocytopenia

Multiple cytokines affect the cellular processes that occur during the transition of a hematopoietic stem cell (HSC) to a platelet. Thrombopoietin (TPO) is the physiological regulator of thrombopoiesis. Although a number of cytokines (interleukin [IL]-1, IL-3, and IL-6) were first evaluated for their ability to lessen the degree of thrombocytopenia occurring during a variety of clinical scenarios, their clinical development was abandoned due to their limited effectiveness or excessive toxicity. Clinical results with TPO and a truncated pegylated form of TPO, megakaryocyte growth and development factor (MGDF), were more promising, but the repeated use of MGDF resulted in the development of neutralizing antibodies. This adverse event halted the further clinical development of not only MGDF but also TPO. IL-11 also affects various stages of megakaryocytopoiesis and thrombopoiesis and its use has been shown to shorten the duration of chemotherapy-induced thrombocytopenia, which led to its approval by the US Food and Drug Administration (FDA). A growing number of new non-immunogenic peptides and non-peptide TPO agonists recently have entered clinical trials. These small molecules appear to be effective therapies and have acceptable toxicity, but additional clinical evaluation will be required prior to their approval for clinical use.

Coagulation abnormalities in patients who have liver disease

The liver plays a central role in the maintenance of normal hemostatic function. Because liver disease alters pathways of coagulation and anticoagulation, patients who have advanced disease can experience severe bleeding or thrombotic complications. Complications of advanced liver disease may also contribute to bleeding or thrombosis. This article reviews and discusses the management of the most common coagulation problems encountered in patients who have end-stage liver disease, which are thrombocytopenia and impaired humoral coagulation as measured by prolongation of the prothrombin time and international normalized ratio.

Review article: thrombocytopenia in chronic liver disease and pharmacologic treatment options

In patients with liver disease, thrombocytopenia is a clinical feature that may represent an obstacle to invasive diagnostic or therapeutic procedures, chemotherapy, and anti-viral treatment. Stimulation of the bone marrow is the most promising therapeutic intervention for thrombocytopenia in patients with chronic liver disease. The description of thrombopoietin and its (de)regulation in patients with chronic liver disease have disclosed new treatment opportunities. Indeed, pharmacologic treatment options for thrombocytopenia can be divided into treatments targeted at the thrombopoietin receptor (synthetic thrombopoietins and thrombopoietin-mimetic agents), and use of cytokines with general thrombopoietic potential. Unfortunately, use of synthetic thrombopoietin was hampered by the development of neutralizing antibodies, and thrombopoietin mimetic agents have not yet entered clinical studies. Interleukin-11 proved to be useful in increasing platelet count in patients with chronic liver disease, although its use is limited by side-effects. Erythropoietin has shown promising results in improving thrombocytopenia in cirrhotic patients. In patients with chronic liver disease, safe and well-tolerated treatments aimed at improving thrombocytopenia are still lacking. Larger studies are needed to evaluate and better characterize the thrombopoietic potential of erythropoietin. Human studies with thrombopoietin-mimetic agents are eagerly awaited in order to assess both effectiveness and safety of these drugs.

Endogenous interleukin-11 (IL-11) levels in newly diagnosed children with acquired severe aplastic anemia (SAA)

BACKGROUND

Impaired hematopoietic growth factor production is a hypothetical contributing factor to the development of acquired severe aplastic anemia (SAA). The serum levels of most hematopoietic cytokines in SAA patients are elevated.

OBJECTIVE

To measure interleukin-11 levels in newly diagnosed SAA children and attempt to correlate levels with disease severity and response to therapy.

DESIGN/METHODS

Following enrollment into a clinical study but prior to treatment, serum samples were obtained from 11 newly diagnosed children with acquired SAA. These samples were collected between May 2000 and September 2002. IL-11 levels were quantified utilizing an ELISA technique.

RESULTS

Ten of the 11 patients had low or normal levels of IL-11 (<85 pg/mL) and one had an elevated level of 409 pg/mL (normal range 15-200 pg/mL).

CONCLUSIONS

The production of IL-11 does not increase in response to thrombocytopenia in most children with SAA. The significance of this laboratory observation is not clear at this time. Further studies are warranted to determine what, if any, role this plays in the development of this disorder and if the administration of recombinant human IL-11 might be beneficial in the treatment of acquired SAA.

Serum thrombopoietin levels are linked to liver function in untreated patients with hepatitis C virus-related chronic hepatitis

BACKGROUND

Thrombocytopenia can be found in patients with chronic hepatitis related to hepatitis C virus (HCV). Both hypersplenism and decreased liver production of thrombopoietin (TPO) have been hypothesized as mechanisms responsible for thrombocytopenia.

AIMS

To assess the presence of relationships among platelet count, spleen size, TPO serum levels, liver histology, and liver function in a group of patients with HCV-related chronic hepatitis.

METHODS

Platelet count, TPO serum levels, and spleen size were assessed in 25 untreated HCV positive chronic hepatitis patients undergoing liver biopsy. These parameters were correlated to liver histology and liver function as evaluated by means of [(13)C]aminopyrine breath test (ABT).

RESULTS

Both platelet counts (146 +/- 48 vs. 202 +/- 56 x 10(9)/1, P < 0.03) and TPO serum levels (103 +/- 24 vs. 158 +/- 7 1 pg/ml, P < 0.02) were lower among patients with high fibrosis scores as compared to patients with low fibrosis scores. Patients with thrombocytopenia as well as patients with high fibrosis scores had lower ABT results as compared to patients with normal platelet counts and patients with no or mild fibrosis, respectively. TPO serum levels were correlated to platelet count (r(s) = 0.493, P = 0.016), and negatively correlated to fibrosis stage (r(s) = -0.545, P = 0.008). Lastly, low TPO serum levels were associated to a decrease in liver function.

CONCLUSIONS

Our study showed that in patients with chronic hepatitis related to HCV infection serum TPO levels are correlated to liver functional impairment and to the degree of liver fibrosis.

The molecular and cellular biology of thrombopoietin: the primary regulator of platelet production

The term thrombopoietin (TPO) was first coined in 1958 and used to describe the humoral substance responsible for causing the platelet count to rise in response to thrombocytopenic stimuli. Despite much progress during the 1980s in the purification and characterization of the humoral regulators of lymphocyte, erythrocyte, monocyte and granulocyte production, the successful search to purify and molecularly clone thrombopoietin did not begin until the oncogene v-mpl was discovered in 1990. Since that time the proto-oncogene c-mpl was identified and, based on homology arguments, believed to encode a hematopoietic cytokine receptor, a hypothesis later proven when the cytoplasmic domain was linked to the ligand binding domain of the IL-4 receptor and shown to support the IL-4 induced growth of hematopoietic cells (Skoda et al., 1993). Finally, two different strategies using c-mpl lead to the identification of a novel ligand for the receptor in 1994 (de Sauvage et al., 1994; Lok et al., 1994; Bartley et al., 1994), a protein that displays all the biologic properties of TPO. This review attempts to distill what has been learned of the molecular and cellular biology of TPO and its receptor during the past several years, and links this information to several new insights into human disease and its treatment.

Plasma thrombopoietin in patients with cavernous transformation of the portal vein

Thrombopoietin (TPO), the primary regulator of thrombopoiesis, is produced mainly in the liver. Previous studies investigating blood TPO in chronic liver diseases revealed conflicting results. It has been suggested that hepatic TPO production is regulated by the portal blood supply to the liver. However, the role of TPO in the pathobiological basis of idiopathic portal vein thrombosis (PVT) and cavernous transformation of the portal vein (CTPV) has not been elucidated. The objective of this study is to assess plasma TPO concentrations in patients with CTPV. Eleven patients (4 men and 7 women, aged 38+/-12 years) with CTPV were studied. Sixteen healthy adults served as the control group (8 men and 8 women, aged 34+/-12 years). Median plasma TPO concentration was 326 pg/mL (range, 15-1402 pg/mL) in the patients with CTPV and 62.65 pg/mL (range, 38.5-102 pg/mL) in the control group (P = .003). In this study, we found significantly higher TPO concentrations in the plasma of patients with CTPV. The higher concentrations could be a result of the altered portal hemodynamics due to thrombosis. Moreover, TPO release by activated platelets might lead to the subsequent propagation of thrombosis in PVT.

Platelet transfusions in the neonatal intensive care unit:factors predicting which patients will require multiple transfusions

BACKGROUND

Previous studies suggest that recombinant thrombopoietin (rTPO) will increase platelet production in thrombocytopenic neonates. However, the target populations of neonates most likely to benefit should be defined. Studies suggest that rTPO will not elevate the platelet count until 5 days after the start of treatment. Therefore, the neonates who might benefit from rTPO are those who will require multiple platelet transfusions for more than 5 days. This study was designed to find means of prospectively identifying these patients.

STUDY DESIGN AND METHODS

A historic cohort study of all patients in the neonatal intensive care unit (NICU) at the University of Florida who received platelet transfusions from January 1, 1997, through December 31, 1998, was conducted.

RESULTS

Of the 1389 patients admitted to the NICU during the study period, 131 (9.4%) received platelet transfusions. Seventeen were treated with extracorporeal membrane oxygenation and were excluded from further analysis. Of the remaining 114 patients, 55 (48%) received one transfusion and 59 (52%) received more than one transfusion (21 had >4). None of the demographic factors examined predicted multiple platelet transfusions. However, two clinical conditions did; liver disease and renal insufficiency. Neonates who received one platelet transfusion had a relative risk of death 10.4 times that in neonates who received none (p = 0.0001). Neonates who received >4 platelet transfusions had a risk of death 29.9 times that in those who received no transfusions (p = 0.0001).

CONCLUSION

NICU patients with liver disease or renal insufficiency who receive one platelet transfusion are likely to receive additional transfusions. Therefore, these patients constitute a possible study population for a Phase I/II rTPO trial.