Search

Introduction: Platelet storage pool diseases (SPD) are a heterogeneous group of bleeding disorders associated with defects in the storage, secretion, or release of platelet granules. Patients with SPD present with a life-long mucocutaneous bleeding diathesis. Our goal was to study the clinical, laboratory, and ultrastructural changes in platelets of patients diagnosed with SPD using a transmission electron microscope (TEM). Methods: In this retrospective, cross-sectional cohort study, medical records of all patients referred for evaluation of a platelet function disorder were screened for an underlying diagnosis of SPD during the period 2010–2020. Results: Sixty-eight patients were identified, among whom 62 (91.2%) had a platelet function assay (PFA) study, of whom 21 (33.9%) were abnormal. Clinical, laboratory, and light transmission aggregometry (LTA) suggested that 10 (14.7%) patients had SPD; five had gray platelet syndrome (GPS), three had Hermansky Pudlak syndrome (HPS), and two had Chedia-Higashi syndrome (CHS). Most of these cases presented with mucocutaneous bleeding diathesis, but a few had oculocutaneous albinism. They were associated with variable abnormalities in the PFA and LTA studies. However, EM studies using TEM showed a reduction/absence of alpha or delta granules in GPS and HPS patients, respectively, but no abnormality in the granules of CHS patients. Conclusions: Although patients with SPD presented with bleeding diathesis, PFA and platelet aggregation studies were inconclusive. Abnormalities in platelet ultrastructure on EM studies demonstrated corroborative evidence for SPD with absent/reduced alpha or delta granules.

Gray platelet syndrome (GPS) is a rare hereditary hemorrhagic disorder characterized by macrothrombocytopenia and the absence of alpha-granules in platelets. Clinically, mild-to-moderate bleeding is the main manifestation, often accompanied by thrombocytopenia, splenomegaly, and myelofibrosis. Here, we present a case of a 15-year-old male patient with a history of hepatosplenomegaly, and thrombocytopenia for 8 years, who presented with sudden generalized abdominal pain. Despite initial suspicion of gastroenteritis, diagnostic imaging revealed an extensive hemoperitoneum. Subsequent genetic testing confirmed the diagnosis of GPS, which had not been previously identified. This case highlights the importance of considering inherited platelet disorders should be considered in adolescents with long-standing thrombocytopenia, and emphasizes the need for thorough evaluation in patients with suggestive symptoms. [ABSTRACT FROM AUTHOR]

Copyright of Ginecología y Obstetricia de México is the property of Federacion Mexicana de Ginecologia y Obstetricia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ana C Glembotsky,1,2 Geraldine De Luca,1,2 Paula G Heller1,2 1Departamento Hematología Investigación, Instituto de Investigaciones Médicas “Dr. A. Lanari”, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; 2Departamento Hematología Investigación, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Instituto de Investigaciones Médicas (IDIM), Buenos Aires, ArgentinaCorrespondence: Paula G HellerDepartamento Hematología Investigación,Instituto de Investigaciones Médicas “Dr. A. Lanari”, Facultad de Medicina, Universidad de Buenos Aires, Combatientes de Malvinas 3150, Buenos Aires, 1427, ArgentinaTel +54 11 5287 3872Email paulaheller@hotmail.comAbstract: The gray platelet syndrome (GPS) is a rare platelet disorder, characterized by impaired alpha-granule biogenesis in megakaryocytes and platelets due to NBEAL2 mutations. Typical clinical features include macrothrombocytopenia, bleeding and elevated vitamin B12 levels, while bone marrow fibrosis and splenomegaly may develop during disease progression. Recently, the involvement of other blood lineages has been highlighted, revealing the role of NBEAL2 outside the megakaryocyte-platelet axis. Low leukocyte counts, decreased neutrophil granulation and impaired neutrophil extracellular trap formation represent prominent findings in GPS patients, reflecting deranged innate immunity and associated with an increased susceptibility to infection. In addition, low numbers and impaired degranulation of NK cells have been demonstrated in animal models. Autoimmune diseases involving different organs and a spectrum of autoantibodies are present in a substantial proportion of GPS patients, expanding the syndromic spectrum of this disorder and pointing to dysregulation of the adaptive immune response. Low-grade inflammation, as evidenced by elevation of liver-derived acute-phase reactants, is another previously unrecognized feature of GPS which may contribute to disease manifestations. This review will focus on the mechanisms underlying the pathogenesis of blood cell abnormalities in human GPS patients and NBEAL2-null animal models, providing insight into the effects of NBEAL2 in hemostasis, inflammation and immunity.Keywords: NBEAL2, gray platelet syndrome, α-granules, immune dysregulation, neutrophils

Gray platelet syndrome (GPS) is an inherited disorder. Patients harboring GPS have thrombocytopenia with large platelets lacking α-granules. A long-term complication is myelofibrosis with pancytopenia. Hematopoietic stem cell transplant (HSCT) could be a curative treatment. We report a male GPS patient with severe pancytopenia, splenomegaly and a secondary myelofibrosis needing red blood cells transfusion. He received an HSCT from a 10/10 matched HLA-unrelated donor after a myeloablative conditioning regimen. Transfusion independence occurred at day+21, with a documented neutrophil engraftment. At day+ 180, we added ruxolitinib to cyclosporine and steroids for a moderate chronic graft versus host disease (GVHD) and persistent splenomegaly. At day+240 GVHD was controlled and splenomegaly reduced. Complete donor chimesrism was documented in blood and marrow and platelets functions and morphology normalized. At day+ 720, the spleen size normalized and there was no evidence of marrow fibrosis on the biopsy. In GPS, HSCT may be a curative treatment in selected patients with pancytopenia and myelofibrosis.

Inherited platelet function disorders (IPFDs) are rare and underdiagnosed in individuals with clinically significant bleeding diathesis. IPFDs are classified according to the causative molecular defects involved in the process of primary hemostasis of platelets, which include the following: 1) adhesion (e.g., Bernard?Soulier syndrome and pseudo-von Willebrand disease), 2) activation (e.g., adenosine diphosphatase receptor defect and thromboxane A2 receptor defect), 3) signal transduction and granule secretion (e.g., gray platelet syndrome, Paris?Trousseau/Jacobsen syndrome, Chediak?Higashi syndrome, and Hermansky?Pudlak syndrome), 4) aggregation (e.g., Glanzmann thrombasthenia), and 5) procoagulant activity (e.g., Scott syndrome). Patients with IPFDs typically present with unexpected mucocutaneous bleeding during early childhood. The diagnosis of these conditions requires several laboratory tests including complete blood cell count, peripheral blood smear, platelet function analysis, light-transmission aggregometry, flow cytometry, electron microscopy, and genetic analysis. Platelet transfusion has been the mainstay of treatment. However, antifibrinolytics, desmopressin, and recombinant activated factor VII are also effective when used as a monotherapy or adjunctive therapy. Importantly, the prevention of bleeding event is the most basic strategy in the management of IPFDs. This review aimed to assess the normal platelet physiology and summarize the current knowledge about the molecular defects, diagnostic evaluation, and treatment strategies of the respective IPFDs. If the cause of the bleeding tendency is difficult to identify, IPFDs should be considered.

Inherited platelet disorders (IPDs), which manifest as primary hemostasis defects, often underlie abnormal bleeding and a family history of thrombocytopenia, bone marrow failure, hematologic malignancies, undefined mucocutaneous bleeding disorder, or congenital bony defects. Wide heterogeneity in IPD types with regard to the presence or absence of thrombocytopenia, platelet dysfunction, bone marrow failure, and dysmegakaryopoiesis is observed in patients. The individual processes involved in platelet production and hemostasis are genetically controlled; to date, mutations of more than 50 genes involved in various platelet biogenesis steps have been implicated in IPDs. Representative IPDs resulting from defects in specific pathways, such as thrombopoietin/MPL signaling; transcriptional regulation; granule formation, trafficking, and secretion; proplatelet formation; cytoskeleton regulation; and transmembrane glycoprotein signaling are reviewed, and the underlying gene mutations are discussed based on the National Center for Biotechnology Information database and Online Mendelian Inheritance in Man accession number. Further, the status and prevalence of genetically confirmed IPDs in Korea are explored based on searches of the PubMed and KoreaMed databases. IPDs are congenital bleeding disorders that can be dangerous due to unexpected bleeding and require genetic counseling for family members and descendants. Therefore, the pediatrician should be suspicious and aware of IPDs and perform the appropriate tests if the patient has unexpected bleeding. However, all IPDs are extremely rare; thus, the domestic incidences of IPDs are unclear and their diagnosis is difficult. Diagnostic confirmation or differential diagnoses of IPDs are challenging, time-consuming, and expensive, and patients are frequently misdiagnosed. Comprehensive molecular characterization and classification of these disorders should enable accurate and precise diagnosis and facilitate improved patient management.

Homozygosity/compound heterozygosity for loss of function mutations in neurobeachin-like 2 (NBEAL2) is causative for Gray platelet syndrome (GPS; MIM #139090), characterized by thrombocytopenia and large platelets lacking α-granules and cargo. Most GPS-associated NBEAL2 mutations generate nonsense codons; frameshifts causing premature translation termination and/or changes in mRNA splicing have also been observed. Data regarding NBEAL2 protein expression in GPS patients is limited. We observed absence of NBEAL2 in platelets from GPS patients with 3 different genotypes, and reduced/truncated platelet NBEAL2 has been reported for others. GPS is commonly associated with mild bleeding, but lifethreatening bleeding has been reported in some cases. A common long-term complication in GPS patients is myelofibrosis; splenomegaly is less common but sometimes of sufficient severity to merit splenectomy. Like GPS patients, mice lacking NBEAL2 expression exhibit macrothrombocytopenia, deficiency of platelet α-granules, splenomegaly, myelofibrosis, impaired platelet function and abnormalities in megakaryocyte development. Animal studies have also reported impaired platelet function in vivo using laser injury and thrombo-inflammation models. NBEAL2 is a large gene with 54 exons, and several putative functional domains have been identified in NBEAL2, including PH (pleckstrin homology) and BEACH (beige and Chediak-Higashi) domains shared with other members of a protein family that includes LYST and LRBA, also expressed by hematopoietic cells. Potential NBEAL2-interacting proteins have recently been identified, and it is expected that current and future efforts will reveal the cellular mechanisms by which NBEAL2 facilitates platelet development and supports hemostatic function.

Gray platelet syndrome (GPS) is a rare, inherited bleeding disorder characterized by the defect of platelet α-granule. Up to date, these are only four studies identifying NBEAL2 gene correlated with GPS. In the current report, we present a Chinese GPS patient who had severe bleeding tendency, abnormalities of platelet functions, and absence of platelet α-granules. Genomic DNA sequencing for the patient identified a nonsense mutation (g.27713C>A) of NBEAL2 gene (g.NG__031914.1) resulting in a premature protein (p.Glu1726*). In comparison with the reported patients, we conclude that homozygotes with nonsense or deletion mutation leading to a premature stop codon exhibit more serious bleeding problem than those with missense mutations.

Gray platelet syndrome (GPS) is an inherited disorder. Patients harboring GPS have thrombocytopenia with large platelets lacking α-granules. A long-term complication is myelofibrosis with pancytopenia. Hematopoietic stem cell transplant (HSCT) could be a curative treatment. We report a male GPS patient with severe pancytopenia, splenomegaly and a secondary myelofibrosis needing red blood cells transfusion. He received an HSCT from a 10/10 matched HLA-unrelated donor after a myeloablative conditioning regimen. Transfusion independence occurred at day+21, with a documented neutrophil engraftment. At day+ 180, we added ruxolitinib to cyclosporine and steroids for a moderate chronic graft versus host disease (GVHD) and persistent splenomegaly. At day+240 GVHD was controlled and splenomegaly reduced. Complete donor chimesrism was documented in blood and marrow and platelets functions and morphology normalized. At day+ 720, the spleen size normalized and there was no evidence of marrow fibrosis on the biopsy. In GPS, HSCT may be a curative treatment in selected patients with pancytopenia and myelofibrosis. [ABSTRACT FROM AUTHOR]

Storage pool deficiency (SPD) is a group of rare platelet disorders that result from deficiencies in α-granules, δ-granules, or both. One type of α-SPD is gray platelet syndrome (GPS), caused by mutations in the neurobeachin-like 2 (NBEAL2) gene that results in a bleeding diathesis, thrombocytopenia, splenomegaly, and progressive myelofibrosis. Due to the lack of α-granules, platelets have a gray and degranulated appearance by light microscopy. However, definitive diagnosis of GPS requires confirmation of α-granule deficiency by electron microscopy. Treatment is nonspecific, with the conservative utilization of platelet transfusions being the most important form of therapy. We present a case of a 17-year-old female with a past medical history of thrombocytopenia, first identified at the age of five. Her clinical symptomatology included chronic fatigue, gingival bleeding, bruising, menorrhagia, and leg pain. This report will discuss both the clinical and the pathophysiologic aspects of this rare platelet disorder. [ABSTRACT FROM AUTHOR]

El artículo ofrece información sobre los estudios de investigación presentados en el concurso para federated médicos en España en 2019. Los temas discutidos en los trabajos incluyen gray platelet síndrome, urosepsis durante el embarazo, y trasplante de hígado y embarazo. También se está debatiendo los temas como rabdomiólisis durante el embarazo y los factores de riesgo de mortalidad por perinatales en fetos con cardiopatías congénitas.

Gri trombosit (platelet) sendromu (GPS), trombositopeni ve ışık mikroskopunda soluk görünen kusurlu trombositlerle karakterize, otozomal resesif geçişli bir hastalıktır. Hastalarda kolay morarma, burun kanaması, menoraji ve uzun kanamalar görülmektedir. GPS için spesifik bir tedavi bulunmamaktadır dolayısı ile hastalığa karşı, riskleri öngörmek ve kanamanın önlenmesi için trombosit fonksiyonunu bozan ilaçlardan kaçınmak gerekmektedir. Bu olgu sunumunda, tekrarlayan anormal kanama atakları olan ve GPS bulgusu bulunan bir vaka sunulmaktadır.

Background: Beyond their role in hemostasis and thrombosis, platelets are also important mediators of inflammation by the release of hundreds of factors stored in their α-granules. Mutations in Nbeal2 cause gray platelet syndrome (GPS), characterized by the lack of platelet α-granules. This study aims to evaluate the immunological (proinflammatory) effects of platelet α-granules.Study Design and Methods: We performed an experiment using Nbeal2-/- mice, the mouse model of GPS. Systemic inflammation was induced by intravenous injection of lipopolysaccharide (LPS). Inflammatory response was assessed by quantification of inflammatory soluble factors and platelet biological response modifiers.Results: The lack of Nbeal2 (in Nbeal2 -/- mice, compared with controls) significantly reduced the recruitment of circulating neutrophils and monocytes. Moreover, after LPS injection, there was a significant increase in neutrophil and monocyte counts in control animals, compared with Nbeal2 -/- mice. The control of inflammation, evaluated by the production of anti-inflammatory cytokines, appeared to be greater in Nbeal2-/- mice compared with controls. Conversely, the production of certain inflammatory-soluble mediators known to characterize normal platelet secretion, such as soluble CD40 ligand (sCD40L), was decreased under experimental inflammation in Nbeal2 -/- mice.Conclusions: These results show that α-granules play a direct role in platelet-mediated inflammation balance, confirming the need to further investigate platelet-associated inflammatory pathophysiology and inflammatory adverse events related to blood transfusion. [ABSTRACT FROM AUTHOR]

Abstract This manuscript aims to provide a concise review on current diagnostic/ confirmatory strategies of Heparin Induced Thrombocytopenia (HIT) with the combined use of immunological / functional assays in addition to the clinical probability. Laboratory diagnosis of HIT is of primordial importance as the related complications could become rapidly severe and life-threatening and can provoke limb amputation in some cases. The first action in the presence of HIT suspicion is to withdraw heparin and to initiate an alternative anticoagulant. Whilst vitamin K antagonists are not appropriate, anticoagulant options include Fondaparinux, Sodium Danaparoid, DOACs, Argatroban, and Bivalirudin. However, if HIT is excluded, patients can benefit again from the high therapeutic and antithrombotic efficacy of this drug, which remains superior to all the substitutive anticoagulant treatments. HIT is suspected in the presence of a platelet count drop > 50% on 2 successive counts, or a platelet count < 100 G/L, and of a significant clinical probability (4 Ts score). Testing patients' plasma is required for establishing the diagnosis. Laboratory investigation involves first the immunological measurement of heparin dependent IgG antibodies (mainly targeted to Heparin-Platelet Factor 4 complexes). When positive, a functional assay for platelet activation, performed at a low and high heparin concentration, allows confirming this disease. In any case, if the immuno-assay is negative, HIT can be excluded with a high probability, and heparin can be continued (if clinical examination favors this decision). Conversely, the higher the IgG antibody concentration is (and affinity), the higher is the probability of developing HIT. The functional assay has now become for confirming the platelet activation capacity of antibodies, and therefore confirming the presence of HIT. Up to now, the gold reference method for testing antibody-dependent platelet activation is the C14-Serotonin Release Assay, available only in very few laboratories working with radio-isotopes. A simple, sensitive, and accurate flow cytometry assay becomes now available to all clinical sites, and it can be easily used for testing the capacity of heparin dependent-antibodies to activate platelets, at low heparin concentration. This technique can be performed in any laboratory equipped with a flow cytometer and can make the HIT confirmation diagnosis rapidly available, which introduces a great improvement for management of patients with HIT. We believe that an evidence–based update on this topic is timely and well warranted. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS), caused by SFTS virus (SFTSV), is a viral hemorrhagic fever with a high case fatality rate. Favipiravir was reported to be effective in the treatment of SFTSV infection in vivo in type I interferon receptor knockout (IFNAR−/−) mice at treatment dosages of both 60 mg/kg/day and 300 mg/kg/day for a duration of 5 days. In this study, the efficacy of favipiravir at dosages of 120 mg/kg/day and 200 mg/kg/day against SFTSV infection in an IFNAR−/− mouse infection model was investigated. IFNAR−/− mice were subcutaneously infected with SFTSV at a 1.0 × 106 50% tissue culture infectious dose followed by twice daily administration of favipiravir, comprising a total dose of either 120 mg/kg/day or 200 mg/kg/day. The treatment was initiated either immediately post infection or at predesignated time points post infection. Neutralizing antibodies in the convalescent-phase mouse sera was examined by the pseudotyped VSV system. All mice treated with favipiravir at dosages of 120 mg/kg/day or 200 mg/kg/day survived when the treatment was initiated at no later than 4 days post infection. A decrease in body weight of mice was observed when the treatment was initiated at 3–4 days post infection. Furthermore, all control mice died. The body weight of mice did not decrease when treatment with favipiravir was initiated immediately post infection at dosages of 120 mg/kg/day and 200 mg/kg/day. Neutralizing antibodies were detected in the convalescent-phase mouse sera. Similar to the literature-reported peritoneal administration of favipiravir at 300 mg/kg/day, the oral administration of favipiravir at dosages of 120 mg/kg/day and 200 mg/kg/day to IFNAR−/− mice infected with SFTSV was effective. [ABSTRACT FROM AUTHOR]

Abstract: Objective: For immune thrombocytopenia (ITP), efficacy of frontline steroids is well established. However, clinical data comparing various treatment options for refractory or relapsed ITP are limited. We aimed to investigate the outcome of frontline steroid treatment for ITP patients and compare common second‐line modalities in a single institute in Taiwan. Methods: We collected the complete outpatient list over a 6‐month period. Patients were identified from the list, and medical records were reviewed to capture the data retrospectively. The diagnosis of ITP was made by excluding other etiologies. Results: Among 665 patients with thrombocytopenia, the diagnosis of ITP was made in 375. Two hundred and fifty‐seven patients (51 males, median age 45.5) received treatment. Response to steroids was evaluable for 184 patients. Complete response (CR) was achieved in 120 (65.2%) and partial response in 43 (23.3%). In 21 (11.4%) patients, ITP was refractory to steroids. Among those with CR, 76 (63%) patients relapsed in a median of 9.5 months. After relapse or steroid failure, 57 (49%) received azathioprine treatment and 38 (32%) underwent splenectomy. Response rate was 71.4% (38.1% CR) for azathioprine and 91.4% (77.1% CR) for splenectomy. Rituximab was effective in 8 of 10 patients. Conclusion: Steroids are effective frontline treatment for ITP, but relapse is common. Both azathioprine and splenectomy are effective treatment after steroid failure. Rituximab appears to a reasonable second‐line treatment option in our limited experience. [ABSTRACT FROM AUTHOR]

Homozygosity/compound heterozygosity for loss of function mutations in neurobeachin-like 2 (NBEAL2) is causative for Gray platelet syndrome (GPS; MIM #139090), characterized by thrombocytopenia and large platelets lacking α-granules and cargo. Most GPS-associated NBEAL2 mutations generate nonsense codons; frameshifts causing premature translation termination and/or changes in mRNA splicing have also been observed. Data regarding NBEAL2 protein expression in GPS patients is limited. We observed absence of NBEAL2 in platelets from GPS patients with 3 different genotypes, and reduced/truncated platelet NBEAL2 has been reported for others. GPS is commonly associated with mild bleeding, but lifethreatening bleeding has been reported in some cases. A common long-term complication in GPS patients is myelofibrosis; splenomegaly is less common but sometimes of sufficient severity to merit splenectomy. Like GPS patients, mice lacking NBEAL2 expression exhibit macrothrombocytopenia, deficiency of platelet α-granules, splenomegaly, myelofibrosis, impaired platelet function and abnormalities in megakaryocyte development. Animal studies have also reported impaired platelet function in vivo using laser injury and thrombo-inflammation models. NBEAL2 is a large gene with 54 exons, and several putative functional domains have been identified in NBEAL2, including PH (pleckstrin homology) and BEACH (beige and Chediak-Higashi) domains shared with other members of a protein family that includes LYST and LRBA, also expressed by hematopoietic cells. Potential NBEAL2-interacting proteins have recently been identified, and it is expected that current and future efforts will reveal the cellular mechanisms by which NBEAL2 facilitates platelet development and supports hemostatic function. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) causes tick-borne hemorrhagic fever in East Asia. The disease is characterized by high morbidity and mortality. Here, we evaluated the effects of caffeic acid (CA), a coffee-related organic acid with antiviral effects, against SFTSV infection. CA dose-dependently inhibited SFTSV infection in permissive human hepatoma Huh7.5.1–8 cells when SFTSV was added into the culture medium with CA. However, quinic acid (QA), another coffee-related organic acid, did not inhibit SFTSV infection. The 50% inhibitory concentration (IC 50 ) of CA against SFTSV was 0.048 mM, whereas its 50% cytotoxic concentration was 7.6 mM. The selectivity index (SI) was 158. Pre-incubation of SFTSV with CA for 4 h resulted in a greater inhibition of SFTSV infection (IC 50 = 0.019 mM; SI = 400). The pre-incubation substantially decreased viral attachment to the cells. CA treatment of the SFTSV-infected cells also inhibited the infection, albeit less effectively. CA activity after cell infection with SFTSV was more pronounced at a low multiplicity of infection (MOI) of 0.01 per cell (IC 50 = 0.18 mM) than at a high MOI of 1 per cell (IC 50 > 1 mM). Thus, CA inhibited virus spread by acting directly on the virus rather than on the infected cells. In conclusion, CA acted on SFTSV and inhibited viral infection and spread, mainly by inhibiting the binding of SFTSV to the cells. We therefore demonstrated CA to be a potential anti-SFTSV drug for preventing and treating SFTS. [ABSTRACT FROM AUTHOR]

These algorithms and tables will help you quickly assess the severity of the 2 blood abnormalities and delineate between life-threatening and benign causes. [ABSTRACT FROM AUTHOR]

The article examines congenital macrothrombocytopenia (CMTP), which is characterized by thrombocytopenia and giant platelets with variable bleeding tendency. Topics discussed include common features in previous CMTP cases with GFI1B mutations, six transcriptional regulator genes that are associated with the early steps of differentiation from MkPs into megakaryocytes, and information on a family with autosomal dominant CMTP.

Gray platelet syndrome (GPS) is a rare, inherited bleeding disorder characterized by the defect of platelet α-granule. Up to date, these are only four studies identifying NBEAL2 gene correlated with GPS. In the current report, we present a Chinese GPS patient who had severe bleeding tendency, abnormalities of platelet functions, and absence of platelet α-granules. Genomic DNA sequencing for the patient identified a nonsense mutation (g.27713C>A) of NBEAL2 gene (g.NG__031914.1) resulting in a premature protein (p.Glu1726*). In comparison with the reported patients, we conclude that homozygotes with nonsense or deletion mutation leading to a premature stop codon exhibit more serious bleeding problem than those with missense mutations. [ABSTRACT FROM AUTHOR]

Mutations in NBEAL2, the gene encoding the scaffolding protein Nbeal2, are causal of gray platelet syndrome (GPS), a rare recessive bleeding disorder characterized by platelets lacking a-granules and progressive marrow fibrosis. We present here the interactome of Nbeal2 with additional validation by reverse immunoprecipitation of Dock7, Sec16a, and Vac14 as interactors of Nbeal2. We show that GPS-causing mutations in its BEACH domain have profound and possible effects on the interaction with Dock7 and Vac14, respectively. Proximity ligation assays show that these 2 proteins are physically proximal to Nbeal2 in human megakaryocytes. In addition, we demonstrate that Nbeal2 is primarily localized in the cytoplasm and Dock7 on the membrane of or in a-granules. Interestingly, platelets from GPS cases and Nbeal2-/- mice are almost devoid of Dock7, resulting in a profound dysregulation of its signaling pathway, leading to defective actin polymerization, platelet activation, and shape change. This study shows for the first time proteins interacting with Nbeal2 and points to the dysregulation of the canonical signaling pathway of Dock7 as a possible cause of the aberrant formation of platelets in GPS cases and Nbeal2-deficient mice. [ABSTRACT FROM AUTHOR]

Background: Clinical characteristics and the prognostic significance of changes in mean platelet volume (MPV) during hospitalization for community-acquired pneumonia (CAP) have not been investigated.Methods: Among 976 adults hospitalized for CAP, clinical characteristics, in-hospital outcomes (transfer to the intensive care unit, treatment with mechanical ventilation, prolonged hospital stay and death), and all-cause mortality following discharge, were compared according to ΔMPV (MPV on discharge minus MPV on admission): groups A (no rising MPV, ΔMPV < 0.6 fL) and B (rising MPV, ΔMPV ≥ 0.6 fL).Results: Groups A and B comprised 83.8% and 16.2% of patients, respectively. Patients with a rise in MPV were more likely to be older, and to present with renal dysfunction, cerebrovascular disorder and severe pneumonia than were patients with no rise in MPV. On discharge, lower values of platelets and higher levels of neutrophils were observed in group B. Rising MPV strongly predicted a need for mechanical ventilation and in-hospital death (the respective relative risks: 2.62 and 6.79; 95% confidence intervals: 1.54-4.45 and 3.48-13.20). The respective 90-day, 3-year and total (median follow-up of 54 months) mortality rates were significantly higher in group B (29.1%, 43.0% and 50.0%) than group A (7.3%, 24.2% and 32.6%), p < 0.001 for all comparisons. A rise in MPV was a powerful predictor of all-cause mortality (relative risk 1.26 and 95% confidence interval 1.11-1.43).Conclusions: Rising MPV during hospitalization for CAP is associated with a more severe clinical profile than no rise in MPV. A rise in MPV strongly predicts in-hospital and long-term mortality. [ABSTRACT FROM AUTHOR]

The neurobeachin-like 2 protein (Nbeal2) belongs to the family of beige and Chediak--Higashi (BEACH) domain proteins. Loss-offunction mutations in the human NBEAL2 gene or Nbeal2 deficiency in mice cause gray platelet syndrome, a bleeding disorder characterized by macrothrombocytopenia, splenomegaly, and paucity of α-granules in megakaryocytes and platelets. We found that in mast cells, Nbeal2 regulates the activation of the Shp1-STAT5 signaling axis and the composition of the c-Kit/STAT signalosome. Furthermore, Nbeal2 mediates granule formation and restricts the expression of the transcription factors, IRF8, GATA2, and MITF as well as of the cell-cycle inhibitor p27, which are essential for mast cell differentiation, proliferation, and cytokine production. These data demonstrate the relevance of Nbeal2 in mast cells above and beyond granule biosynthesis. [ABSTRACT FROM AUTHOR]

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder characterized by low platelet counts. First-line treatment includes intravenous immunoglobulin (IVIg), however, its working mechanism remains incompletely understood. We investigated splenic and thymic dendritic cell (DC) subsets upon IVIg treatment in a well-characterized active murine model of ITP. During active disease, there was a significant peripheral deficiency of splenic tolerizing SIRPα+ DCs which could be rescued by IVIg therapy, increasing platelet counts. These splenic tolerizing DC changes were associated with an abrogation of the thymic-retention of tolerizing DCs, suggesting that IVIg may raise platelet counts in ITP by modulating peripheral numbers of tolerizing DCs. [ABSTRACT FROM PUBLISHER]

Background: Vitamin K inhibitors (e.g. warfarin) and indirect thrombin inhibitors (e.g. heparin) are widely used to prevent thromboembolic disorders (e.g. myocardial infarction, venous thromboembolism, and stroke). These agents have been mainstays of anticoagulation for people older than 60 years. However, their administration is associated with a risk of bleeding and requires careful monitoring of patients. Novel oral anticoagulants (NOACs), such as dabigatran, are significantly safer in preventing thromboembolism than warfarin and heparin (sporadically causes thrombocytopenia) and are more specific for their target protein, thrombin. The major advantage of dabigatran, a direct thrombin inhibitor, is that it reversibly inhibits both free and clot-bound thrombin by tight binding affinity and the predictable pharmacodynamic effect. A few studies, however, reported that dabigatran can cause thrombocytopenia, although the underlying mechanism remains unclear. Thus, an antidote for dabigatran was developed to prevent thrombocytopenia.Case Presentation: In this report, we discuss two cases of thrombocytopenia and purpura after dabigatran treatment. A 73-year-old man showed hemorrhagic necrotic skin lesions on his neck and right hand. He was administered dabigatran (220 mg/day) for cerebral infarction for three days and his platelet count decreased abruptly (6000/μL). This suggested that dabigatran had caused thrombocytopenia and purpura; therefore, dabigatran administration was discontinued. The results of a blood test, performed 14 days after stopping dabigatran treatment, showed that the platelet count had recovered to the normal range of more than 150,000/μL. A 75-year-old woman had taken warfarin continuously for 8 years. However, she had a new cerebral infarction. Therefore, warfarin treatment was replaced with dabigatran (300 mg/day). Her platelet count decreased (41,000/μL) significantly and dabigatran treatment was discontinued. The blood test results show that platelet counts gradually recovered to the normal range.Conclusions: Dabigatran application may cause bleeding; therefore, careful monitoring during dabigatran treatment is required to prevent thrombocytopenia. An explanation is that the interaction of dabigatran with thrombin, because of its strong binding affinity, may cause the observed thrombocytopenia. [ABSTRACT FROM AUTHOR]

Background: Transfusion-related immunomodulation (TRIM) encompasses immunosuppressive and proinflammatory effects induced by red blood cell (RBC) transfusion. Changes that occur during storage in the RBC product have been hypothesized to underlie TRIM, mediated by tolerance of toll-like receptors (TLR). We investigated whether transfusion of 35-day-stored autologous RBCs alters cytokine production in response to stimulation with lipopolysaccharide (LPS) or lipotheic acid (LTA), in a clinically relevant model of endotoxemia.Study Design and Methods: Eighteen volunteers received 2 ng/kg LPS intravenously, followed by normal saline or 2- or 35-day-stored autologous RBC transfusion. Before LPS, before transfusion, and 6 hours after transfusion blood was collected to measure cytokine gene expression. Whole blood was used for ex vivo stimulation with LPS and LTA, after which cytokine levels were measured with enzyme-linked immunosorbent assay.Results: In vivo LPS induced a biphasic response in cytokine mRNA with peak values 2 hours after LPS infusion. Storage time of RBC transfusion did not influence cytokine mRNA levels. In vivo infusion of LPS resulted in tolerance for ex vivo stimulation with LPS and LTA. However, transfusion of either fresh or stored RBCs did not further affect the capacity to produce cytokines after ex vivo stimulation.Conclusion: In a clinically relevant model of human endotoxemia, autologous transfusion of 35-day-stored RBCs does not influence cytokine mRNA levels nor does it change the capacity of white blood cells in whole blood to produce cytokines after ex vivo stimulation with LPS or LTA. [ABSTRACT FROM AUTHOR]

Background: Transfusion-mediated human parvovirus B19 (PVB19) infection is rare but often causes severe hematologic disorders. In Japan, routine blood donor screening for PVB19 antigen (detection sensitivity, 106.4 IU/mL) using a chemiluminescent enzyme immunoassay (CLEIA) was introduced in 2008. However, there is no consensus on the minimal infectious dose of PVB19 permissible for red blood cells (RBCs).Case Report: A 64-year-old man, who had received hemodialysis for diabetic nephropathy for 5 years, underwent an RBC transfusion for anemia caused by hemorrhagic enterocolitis. He developed persistent high fever and progressive thrombocytopenia. He was diagnosed with PVB19 infection when a marrow examination showed giant erythroblasts, and his serum was positive for PVB19 DNA. His serum was negative for PVB19 immunoglobulin (Ig)M and IgG before transfusion, but positive for both after transfusion. This PVB19 infection was deemed to be transmitted by the RBC transfusion because low levels of PVB19 DNA (1.10 × 104 IU/mL) were detected in one of the blood donors. A DNA homology test of PVB19 showed complete genomic identity between the virus in the donor and our patient.Conclusion: We report a patient who developed persistent PVB19 infection from an RBC transfusion containing low levels of PVB19. This is the second case of transfusion-mediated PVB19 infection since the introduction of CLEIA in 2008. Transmission may occur in immunocompromised patients lacking PVB19-neutralizing antibodies. The report of further such cases will allow the establishment of minimal threshold values and more effective screening tests for PBV19 transmission through RBC products. [ABSTRACT FROM AUTHOR]

Background: Studies in murine models suggested that platelet desialylation was an important mechanism of thrombocytopenia during sepsis. Methods: First, we performed a prospective, multicenter, observational study that enrolled septic patients with or without thrombocytopenia to determine the association between platelet desialylation and thrombocytopenia in patients with sepsis, severe sepsis, and septic shock. Gender- and age-matched healthy adults were selected as normal controls in analysis of the platelet desialylation levels (study I). Next, we conducted an open-label randomized controlled trial (RCT) in which the patients who had severe sepsis with thrombocytopenia (platelet counts ≤50 × 109/L) were randomly assigned to receive antimicrobial therapy alone (control group) or antimicrobial therapy plus oseltamivir (oseltamivir group) in a 1:1 ratio (study II). The primary outcomes were platelet desialylation level at study entry, overall platelet response rate within 14 days post-randomization, and all-cause mortality within 28 days post-randomization. Secondary outcomes included platelet recovery time, the occurrence of bleeding events, and the amount of platelets transfused within 14 days post-randomization. Results: The platelet desialylation levels increased significantly in the 127 septic patients with thrombocytopenia compared to the 134 patients without thrombocytopenia. A platelet response was achieved in 45 of the 54 patients in the oseltamivir group (83.3%) compared with 34 of the 52 patients in the control group (65.4%; P = 0.045). The median platelet recovery time was 5 days (interquartile range 4-6) in the oseltamivir group compared with 7 days (interquartile range 5-10) in the control group (P = 0.003). The amount of platelets transfused decreased significantly in the oseltamivir group compared to the control group (P = 0.044). There was no difference in the overall 28-day mortality regardless of whether oseltamivir was used. The Sequential Organ Failure Assessment score and platelet recovery time were independent indicators of oseltamivir therapy. The main reason for all of the mortalities was multiple-organ failure. Conclusions: Thrombocytopenia was associated with increased platelet desialylation in septic patients. The addition of oseltamivir could significantly increase the platelet response rate, shorten platelet recovery time, and reduce platelet transfusion. [ABSTRACT FROM AUTHOR]

Gray platelet syndrome (GPS) is a rare (<1/1 000 000) and inherited platelet function disorder characterized by macrothrombocytopenia, α-granule deficiency, and hemorrhages. Bleeding intensity does not correlate with platelet count nor with functional test results. We hereby describe the perioperative bleeding prevention and management of a patient with GPS requiring multiple redo cardiac surgeries. [ABSTRACT FROM AUTHOR]

Background: Severe fever with thrombocytopenia syndrome is an emerging infectious disease caused by a novel phlebovirus belonging to the family Bunyaviridate. Emergence of encephalitis/encephalopathy during severe fever with thrombocytopenia syndrome progression has been identified as a major risk factor associated with a poor prognosis. Here we report the case of a severely ill patient with severe fever with thrombocytopenia syndrome virus-associated encephalitis/encephalopathy characterized by a lesion of the splenium, which resolved later.Case Presentation: A 56-year-old Japanese man presented with fever and diarrhea, followed by dysarthria. Diffusion-weighted magnetic resonance imaging demonstrated high signal intensity in the splenium of the corpus callosum. The severe fever with thrombocytopenia syndrome virus genome was detected in our patient's serum, and the clinical course was characterized by convulsion, stupor, and hemorrhagic manifestations, with disseminated intravascular coagulation and hemophagocytic lymphohistiocytosis. Supportive therapy not including administration of corticosteroids led to gradual improvement of the clinical and laboratory findings, and magnetic resonance imaging demonstrated resolution of the splenial lesion. The serum severe fever with thrombocytopenia syndrome viral copy number, which was determined with the quantitative reverse-transcription polymerase chain reaction, rapidly decreased despite the severe clinical course. Our patient's overall condition improved, allowing him to be eventually discharged.Conclusions: Patients with encephalitis/encephalopathy due to severe fever with thrombocytopenia syndrome virus infection may have a favorable outcome, even if they exhibit splenial lesions and a severe clinical course; monitoring the serum viral load may be of value for prediction of outcome and potentially enables the avoidance of corticosteroids to intentionally cause opportunistic infection. [ABSTRACT FROM AUTHOR]

Fetal or neonatal alloimmune thrombocytopenia ( FNAIT) is a potentially life-threatening disease where fetal platelets are destroyed by maternal anti-platelet IgG alloantibodies. The clinical outcome varies from asymptomatic, to petechiae or intracranial haemorrhage, but no marker has shown reliable correlation with severity, making screening for FNAIT impractical and highly inefficient. We recently found IgG Fc-glycosylation towards platelet and red blood cell antigens to be skewed towards decreased fucosylation, increased galactosylation and sialylation. The lowered core-fucosylation increases the affinity of the pathogenic antibodies to Fcγ RIIIa and Fcγ RIIIb, and hence platelet destruction. Here we analysed the N-linked glycans of human platelet antigen ( HPA)-1a specific IgG1 with mass spectrometry in large series of FNAIT cases ( n = 166) including longitudinal samples ( n = 26). Besides a significant decrease in Fc-fucosylation after the first pregnancy ( P = 0·0124), Fc-glycosylation levels remained stable during and after pregnancy and in subsequent pregnancies. Multiple logistic regression analysis identified anti- HPA-1a -fucosylation ( P = 0·006) combined with galactosylation ( P = 0·021) and antibody level ( P = 0·038) correlated with bleeding severity , making these parameters a feasible marker in screening for severe cases of FNAIT. [ABSTRACT FROM AUTHOR]

Introduction Inherited macrothrombocytopenia represents a heterogeneous group of disorders which are characterized by the presence of a reduced number of abnormally large platelets in the circulation, which may or may not be associated with a bleeding tendency. In spite of several causative genes having been identified, the underlying genetic defects remain to be identified in approximately half of the cases. Aims To understand the molecular pathology of isolated giant platelet disorder from India. Materials and methods We studied 112 cases that were referred for investigation of macrothrombocytopenia. Agonist induced platelet aggregation and platelet GP1b/ IX/V receptor expression were investigated to assess GP1b/ IX/V receptor expression and the GP1 BA, GP1 BB, GP9, ABCG5, ABCG8, TUBB1 and MYH9 genes were analysed to identify candidate gene defects. Results Twenty-three candidate gene defects were identified in 48 of 112 cases, 20 of which were novel. Of the candidate defects identified, 91% were missense and 9% were nonsense variations. The missense variations were in GP9 (9), ABCG5 (4), GP1 BB (3), GP1 BA (3) and MYH9 (2), while the nonsense defects occurred in MYH9 (1) and GP1 BA (1). Conclusions This study increases the understanding of the molecular basis of an isolated giant platelet disorder, a common heterogeneous condition prevalent in north and eastern India. [ABSTRACT FROM AUTHOR]

During hematopoiesis, transcriptional programs are essential for the commitment and differentiation of progenitors into the different blood lineages. GATA1 is a transcription factor expressed in several hematopoietic lineages and essential for proper erythropoiesis and megakaryopoiesis. Megakaryocyte-specific genes, such as GP1BA, are known to be directly regulated by GATA1. Mutations in GATA1 can lead to dyserythropoietic anemia and pseudo gray-platelet syndrome. Selective loss of Gata1 expression in adult mice results in macrothrombocytopenia with platelet dysfunction, characterized by an excess of immature megakaryocytes. To specifically analyze the impact of Gata1 loss in mature committed megakaryocytes, we generated Gata1-Lox|Pf4-Cre mice (Gata1cKOMK). Consistent with previous findings, Gata1cKOMK mice are macrothrombocytopenic with platelet dysfunction. Supporting this notion we demonstrate that Gata1 regulates directly the transcription of Syk, a tyrosine kinase that functions downstream of Clec2 and GPVI receptors in megakaryocytes and platelets. Furthermore, we show that Gata1cKOMK mice display an additional aberrant megakaryocyte differentiation stage. Interestingly, these mice present a misbalance of the multipotent progenitor compartment and the erythroid lineage, which translates into compensatory stress erythropoiesis and splenomegaly. Despite the severe thrombocytopenia, Gata1cKOMK mice display a mild reduction of TPO plasma levels, and Gata1cKOMK megakaryocytes show a mild increase in Pf4 mRNA levels; such a misbalance might be behind the general hematopoietic defects observed, affecting locally normal TPO and Pf4 levels at hematopoietic stem cell niches. [ABSTRACT FROM AUTHOR]