A case of familial thrombocytosis: possible role of altered thrombopoietin production

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.

Epidemiology of the classical myeloproliferative neoplasms: The four corners of an expansive and complex map

The classical myeloproliferative neoplasms (MPNs), specifically chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF), represent clonal myeloid disorders whose pathogenesis is driven by well-defined molecular abnormalities. In this comprehensive review, we summarize the epidemiological literature and present our own analysis of the most recent the Surveillance, Epidemiology, and End Results (SEER) program data through 2016. Older age and male gender are known risk factors for MPNs, but the potential etiological role of other variables is less established. The incidences of CML, PV, and ET are relatively similar at 1.0-2.0 per 100,000 person-years in the United States, while PMF is rarer with an incidence of 0.3 per 100,000 person-years. The availability of tyrosine kinase inhibitor therapy has dramatically improved CML patient outcomes and yield a life expectancy similar to the general population. Patients with PV or ET have better survival than PMF patients.

Platelet Counting: Ugly Traps and Good Advice. Proposals from the French-Speaking Cellular Hematology Group (GFHC)

Despite the ongoing development of automated hematology analyzers to optimize complete blood count results, platelet count still suffers from pre-analytical or analytical pitfalls, including EDTA-induced pseudothrombocytopenia. Although most of these interferences are widely known, laboratory practices remain highly heterogeneous. In order to harmonize and standardize cellular hematology practices, the French-speaking Cellular Hematology Group (GFHC) wants to focus on interferences that could affect the platelet count and to detail the verification steps with minimal recommendations, taking into account the different technologies employed nowadays. The conclusions of the GFHC presented here met with a "strong professional agreement" and are explained with their rationale to define the course of actions, in case thrombocytopenia or thrombocytosis is detected. They are proposed as minimum recommendations to be used by each specialist in laboratory medicine who remains free to use more restrictive guidelines based on the patient’s condition.

Extreme Thrombocytosis in a Child: Laboratory Approaches and Diagnostic Challenges

Thrombocytosis in children as well as in adult is defined as platelet count ≥ 450 × 109/L, and it is usually a reactive feature to various medical disorders. However, extreme thrombocytosis (platelet count ≥ 1000 × 109/L) is an uncommon finding among pediatric and adult patients, which may indicate more than a reactive phenomenon. We describe a case of a five-year-old boy who was admitted due to recurrent epistaxis. He had no history of allergic tendency or trauma. Physical examination was unremarkable except for shotty neck nodes. Laboratory results at presentation showed normal hemoglobin and total leukocyte count with eosinophilia (0.92 × 109/L), and extreme thrombocytosis. Other relevant investigations including coagulation profile, serum ferritin, liver, and renal function tests were all within normal ranges. Stool samples for ova and cysts were negative. The peripheral blood smear and bone marrow aspirate confirmed thrombocytosis with increased megakaryocytic proliferation and no artefactual reasons for the high platelets such as red blood cell fragments. Different causes of thrombocytosis in childhood were investigated after considering the possible differential diagnoses for extreme thrombocytosis.

Study of the Effects and Mechanisms of Ginsenoside Compound K on Myelosuppression

Ginsenoside compound K (CK) is not a ginsenoside that naturally exists in Panax ginseng Meyer. However, CK is a major metabolite of ginsenoside Rb₁, Rb₂, or Rc in the intestine under the effects of bacteria. In this study, we first investigated the effects of CK on myelosuppression in mice induced by cyclophosphamide (CTX). The respective quantities of white blood cells, blood platelets, and bone marrow nucleated cells (BMNCs) were determined to be 8.54 ± 0.91 (10⁹/L), 850.90 ± 44.11 (10⁹/L), and 1.45 ± 0.22 (10⁹/L) in the CK-H group by detecting peripheral blood cells and BMNCs. CK-H and CK-L both increased the thymus index by up to 0.62 ± 0.06 (mg/g) and 0.52 ± 0.09 (mg/g), respectively, and significantly increased the yields of colony formation units-granulocyte monocyte and colony formation units-megakaryocytic. According to our study, CK could control apoptosis and promote cells to enter the normal cell cycle by the bcl-2/bax signaling pathway and MEK/ERK signaling pathway. Therefore, the BMNCs could proliferate and differentiate normally after entering the normal cell cycle. So the peripheral blood cells could show a trend of returning to normal. The recovery of peripheral blood cells resulting in the level of cytokines tended to normal. This process may be the mechanisms of CK on myelosuppression. This study provides a reference for ginseng in the treatment of myelosuppression.

Studies of the effects and mechanisms of ginsenoside Re and Rk3 on myelosuppression induced by cyclophosphamide

Background

Ginsenoside Re (Re) is one of the major components of Panax ginseng Meyer. Ginsenoside Rk₃ (Rk₃) is a secondary metabolite of Re. The aim of this study was to investigate and compare the effects and underlying mechanisms of Re and Rk₃ on cyclophosphamide-induced myelosuppression.

Methods

The mice myelosuppression model was established by intraperitoneal (i.p.) injection of cyclophosphamide. Peripheral blood cells, bone marrow nucleated cells, and colony yield of hematopoietic progenitor cells in vitro were counted. The levels of erythropoietin, thrombopoietin, and granulocyte macrophage colony-stimulating factor in plasma were measured by enzyme-linked immunosorbent assay. Bone marrow cell cycle was performed by flow cytometry. The expression of apoptotic protein bcl-2, bax, and caspase-3 was detected by Western blotting.

Results

Both Re and Rk₃ could improve peripheral blood cells, bone marrow nucleated cell counts, thymus index, and spleen index. Furthermore, they could enhance the yield of colonies cultured in vitro and make the levels of granulocyte macrophage colony-stimulating factor, erythropoietin, and thrombopoietin normal, reduce the ratio of G₀/G₁ phase cells, and increase the proliferation index. Finally, Re and Rk₃ could upregulate the expression of bcl-2, whereas they could downregulate the expression of bax and caspase-3.

Conclusion

Re and Rk₃ could improve the hematopoietic function of myelosuppressed mice. The effect of Rk₃ was superior to that of Re at any dose. Regulating the levels of cytokines, promoting cells enter the normal cell cycle, regulating the balance of bcl-2/bax, and inhibiting the expression of caspase-3 may be the effects of Re and Rk₃ on myelosuppression.

Genetic origins and clinical phenotype of familial and acquired erythrocytosis and thrombocytosis

Familial and acquired erythrocytosis and thrombocytosis are characterized by myeloid lineage hyperproliferation, which is either single or multi-lineage in origin. The single lineage disorders exhibit Mendelian inheritance with polyclonal hematopoiesis and often arise from a single genetic defect. In contrast, the multi-lineage disorders exhibit complex patterns of inheritance with multi-genetic origins and clonal hematopoiesis. They have the potential to acquire JAK2 somatic mutations, but this is not the primary event. Identification of the disease-causing genes will enable better classification of familial and acquired erythrocytosis and thrombocytosis. Furthermore, it will provide an insight into the mechanisms regulating myeloid cell proliferation.

Familial thrombocytosis caused by the novel germ-line mutation p.Pro106Leu in the MPL gene

Familial thrombosis (FT) has been described as a rare autosomal-dominant disorder, mostly caused by activating mutations of the thrombopoietin gene (THPO). Other cases of FT have been linked to one of two different germline mutations in the myeloproliferative leukaemia virus oncogene gene (MPL), which codes for the thrombopoietin receptor MPL. We studied an Arab family with two siblings with severe thrombocytosis by linkage analysis and obtained evidence for linkage to MPL. Sequencing revealed homozygosity for the novel MPL germline mutation p.Pro106Leu (c.317C > T) in the two siblings. Subsequently, homozygosity for p.Pro106Leu was identified in six further FT patients from three other Arab families. Of 18 heterozygous carriers, 14 had normal platelet counts, while four had mild thrombocytosis. Strong support for association of the novel MPL mutation p.Pro106Leu with development of familial thrombocytosis has been obtained. Overall, p.Pro106Leu was absent on 386 alleles of 193 healthy German controls and present on 14 of 426 alleles (3.3%) of 213 unrelated Arabs, which was statistically significantly different (P < 0.001, Fisher's exact test). We assume that p.Pro106Leu is a frequent MPL mutation in the Arab population, leading to severe thrombocytosis in homozygotes and occasionally to mild thrombocytosis in heterozygotes. In the families described the mode of inheritance could be regarded as autosomal-recessive with possible mild heterozygote manifestation rather than autosomal-dominant with high penetrance as usually seen in FT.

A family with hereditary thrombocythaemia and normal genes for thrombopoietin and c-Mpl

Hereditary thrombocythaemia (HT) is an inherited autosomal dominant disorder. Recent studies reported six different mutations, four within the thrombopoietin (TPO) gene and two within c-Mpl (TPO receptor) gene in six unrelated families with HT. This study investigated the molecular basis of hereditary thrombocythaemia in an Israeli-Jewish family. We screened the genes for TPO and c-Mpl by amplification and sequencing of all the corresponding exons including exon/intron boundaries and promoters. In addition, plasma levels of TPO and erythropoietin (EPO) were measured. No abnormality in the TPO/c-Mpl genes has been identified in affected HT family members. Plasma TPO and EPO levels were found to be normal/low or normal respectively in the individuals affected. In conclusion, lack of a molecular lesion within either TPO or cMpl genes indicate that HT may be caused by factors other than TPO-cMpl axis in this family.