In all, 15-30% of pediatric immune thrombocytopenia (ITP) patients will remain chronically thrombocytopenic at 1 year post diagnosis. All attempts to classify patients at diagnosis have proven ...unsuccessful. We hypothesized that a different pathophysiology is responsible for non-chronic versus chronic pediatric ITP. We aimed to examine differences in the apoptotic markers' presentation at diagnosis between non-chronic and chronic patients.
Blood samples were collected from 42 pediatric patients with newly diagnosed ITP prior to initiation of treatment. We incubated patients' sera with control platelets and compared the results among three research groups: healthy controls, chronic ITP, and non-chronic ITP patients. We measured apoptotic markers phosphatidylserine (PS) exposure and mitochondrial inner membrane potential (ΔΨm) by flow cytometry and the level of human apoptotic proteins by Human Apoptosis Array.
We found increased platelet PS exposure and decreased ΔΨm in response to all ITP patients' sera compared to control subjects. Human Apoptotic Array revealed an increased expression of five apoptotic proteins: BIM, CD40, IGFBP2, P21, and SMAC, following sera incubation of non-chronic pediatric ITP patients, compared to chronic patients' sera, at diagnosis.
Our data contribute to knowledge on apoptosis markers that may aid in predicting the prognosis of children with ITP.
The key message of our article is that children with chronic ITP have a different apoptotic profile compared to non-chronic ITP. Addition to existing literature: This is the first study comparing apoptotic markers between children with chronic ITP to non-chronic ITP.
Our findings indicate that, in the future, apoptotic markers may help to classify ITP patients into non-chronic versus chronic ones, at diagnosis.
is utilized mainly for palliative care worldwide. Ovarian cancer (OC) is a lethal gynecologic cancer. A particular cannabis extract fraction ('F7') and the Poly(ADP-Ribose) Polymerase 1 (PARP1) ...inhibitor niraparib act synergistically to promote OC cell apoptosis. Here we identified genetic pathways that are altered by the synergistic treatment in OC cell lines Caov3 and OVCAR3.
Gene expression profiles were determined by RNA sequencing and quantitative PCR. Microscopy was used to determine actin arrangement, a scratch assay to determine cell migration and flow cytometry to determine apoptosis, cell cycle and aldehyde dehydrogenase (ALDH) activity. Western blotting was used to determine protein levels.
Gene expression results suggested variations in gene expression between the two cell lines examined. Multiple genetic pathways, including Hippo/Wnt, TGF-β/Activin and MAPK were enriched with genes differentially expressed by niraparib and/or F7 treatments in both cell lines. Niraparib + F7 treatment led to cell cycle arrest and endoplasmic reticulum (ER) stress, inhibited cell migration, reduced the % of ALDH positive cells in the population and enhanced PARP1 cleavage.
The synergistic effect of the niraparib + F7 may result from the treatment affecting multiple genetic pathways involving cell death and reducing mesenchymal characteristics.
Mechanisms of platelet activation are triggered by thrombin, adenosine diphosphate (ADP), epinephrine, thromboxane A
, and other soluble agonists which induce signaling via heterotrimeric Gαq, Gαi, ...and Gα12/13 proteins. We have undertaken a study addressing the contribution of these G proteins to platelet activation and clot formation in the presence of eptifibatide, thus excluding outside-in signaling provided by integrin αIIbβ3-fibrinogen engagement. Selective and combined activation of the G proteins was achieved by using combinations of platelet agonists and inhibitors. Platelet activation in platelet-rich plasma was evaluated by P-selectin expression using flow cytometry. Contribution of platelets to whole blood clotting was assessed by rotation thromboelastometry (ROTEM). Selective signaling of Gαq or Gαi but not Gα12/13 promoted P-selectin expression. Further enhancement of P-selectin expression was achieved by ADP-induced combined signaling of Gαq and Gαi, and to more extent by U46619 at high concentration (1.5 μM) induced combined signaling of Gαq and Gα12/13 while maximal P-selectin expression was achieved by thrombin receptor-activating peptide (TRAP)-induced combined signaling of Gαq, Gαi, and Gα12/13. In ROTEM, selective activation of Gαq, Gαi, or Gα12/13 failed to affect blood clotting. Combined signaling of Gαq and Gαi or Gαq and Gα12/13 or all three G proteins shortened the clotting time and stimulated clot strength. Pretreatment of platelets with acetylsalicylic acid did not change the effect of ADP but inhibited the effect of TRAP. Signaling of Gαq and Gα12/13 triggered by U46619 also stimulated clot formation. Combined signaling of either Gαq and Gαi or Gαq and Gα12/13 is sufficient to stimulate maximal platelet activation and enhanced clot formation in platelets treated with inhibitor of integrin αIIbβ3. It could be suggested that outside-in signaling is not necessarily required to fulfill these platelet functions.
Trauma-induced coagulopathy (TIC) is commonly seen among patients with severe injury. The dynamic process of TIC is characterized by variability of the features of the disease.
A model of TIC was ...created. Hemodilution was produced by mixing the blood with 40% Tris/saline solution, fibrinolysis by treating the blood with 160 ng/mL tPA, acidosis by adding 1.2 mg/mL lactic acid achieving pH 7.0 to 7.1, and hypothermia by running the assay at 31°C. Intact blood tested at 37°C served as control. Clot formation was evaluated using rotation thromboelastometry. Platelet adhesion and aggregation were assayed at a shear rate of 1800 s(-) using Impact-R device.
Clotting time was not affected by any of the TIC constituents used. Clotting initiation was reduced by hemodilution and further reduced by additive hypothermia. The propagation phase of blood clotting was reduced by hemodilution, further reduced by additive hypothermia, and maximally reduced if additionally combined with fibrinolysis. No effect of fibrinolysis on clot propagation was observed at 37°C. Maximum clot firmness was reduced by hemodilution, further reduced by additive fibrinolysis, and maximally reduced if additionally combined with hypothermia. No effect of hypothermia on clot strength was observed in the absence of fibrinolysis. Platelet adhesion (percentage of surface coverage) and aggregation (aggregate size) under flow condition were reduced by hemodilution and further reduced by additive acidosis. Introduction of tPA to diluted blood had no effect on platelet function.
The study revealed a differential effect of TIC constituents-hemodilution, hypothermia, fibrinolysis, and acidosis-on clot formation and platelet function. The effect of one factor may influence that of another factor. These data may be helpful to better understand the pathogenesis of TIC and to elaborate an individually tailored treatment strategy.
A new model of TIC is created. Contribution of various constituents to pathogenesis of TIC and their interactions are evaluated.
Glanzmann thrombasthenia (GT) is a severe inherited platelet function disorder (IPFD), presenting with bleeding diathesis and impaired platelet aggregation, is caused by mutations in the genes ITGA2B ...or ITGB3.
We aimed to study the genetic cause of IPFD mimicking GT.
During 2017–2019, 16 patients were referred to our tertiary center with bleeding symptoms, impaired platelet aggregation and normal platelet count and size.
Using flow cytometry, 13/16 patients were diagnosed with GT, yet three patients displayed normal surface expression of the integrins αIIbβ3 and αvβ3, as well as normal integrin αIIbβ3 activation following incubation with the activating monoclonal antibody anti-LIBS6, while platelet activation following ADP or epinephrine was impaired. Whole exome sequencing detected 2 variants in RASGRP2 gene in all 3 patients.
Both RASGRP2 mutations predicted frameshift, premature stop codon (p. I427Mfs*92 and p. R494Afs*54, respectively) and truncated calcium-sensing guanine nucleotide exchange factor CalDAG-GEFI- the major signaling molecule that regulates integrin-mediated aggregation and granule secretion, causing IPFD-18.
Patients who suffer from bleeding diathesis without immune dysregulation, may be mistakenly diagnosed as GT. Further studies are required to confirm the diagnosis of specific IPFD.
Endogenous gene knock‐in using CRIPSR is becoming the standard for fluorescent tagging of endogenous proteins. Some protocols, particularly those that utilize insert cassettes that carry a ...fluorescent protein tag, can yield many types of cells with off‐target insertions that have diffuse fluorescent signal throughout the whole cell in addition to scarce cells with on‐target gene insertions that show the correct sub‐cellular localization of the tagged protein. As such, when searching for cells with on‐target integration using flow cytometry, the off‐target fluorescent cells yield a high percentage of false positives. Here, we show that by changing the gating used to select for fluorescence during flow cytometry sorting, namely utilizing the width of the signal as opposed to the area, we can highly enrich for positively integrated cells. Reproducible gates were created to select even minuscule percentages of correct subcellular signal, and these parameters were validated by fluorescence microscopy. This method is a powerful tool to rapidly enhance the generation of cell lines with correctly integrated gene knock‐ins encoding endogenous fluorescent proteins.
Immune thrombocytopenia (ITP) in pregnant women can cause neonatal thrombocytopenia by transport of antiplatelet autoantibodies across the placenta. Usually, an infant's platelet count normalizes ...within 2 months. We observed neonatal thrombocytopenia that persisted more than 4 months and disappeared following discontinuation of breastfeeding. The aim of our study was to discern whether breast milk of ITP mothers contained antiplatelet antibodies causing persistent thrombocytopenia. We collected milk samples from 3 groups of women: ITP group, 7 women who had ITP during pregnancy; R-ITP group, 6 women who recovered from ITP before pregnancy; and 9 healthy controls. We found increased levels of antiplatelet antibodies of the immunoglobulin A type in the milk of ITP patients compared with the other 2 groups. Similar increase was demonstrated for antibodies binding to αIIbβ3 expressed in cultured cells. Thus, transfer of antiplatelet antibodies from ITP mothers by breastfeeding can be associated with persistent neonatal thrombocytopenia.
•Persistent thrombocytopenia was observed in breastfed neonates of ITP women.•Breast milk of ITP women may contain immunoglobulin A antiplatelet antibodies, which target αIIbβ3 integrin.
Both JAK2V617F and calreticulin (CALR) mutated essential thrombocythemia (ET) patients have different clinical characteristics, with lower thrombosis risk in patients with CALR mutations. To ...elucidate the mechanism for this lower risk we studied platelet function in ET patients with either JAK2V617F or a CALR mutation. Platelet activation state was similar in ET and healthy controls at baseline using P‐selectin and PAC1 flow cytometry analysis. However, CALR mutated platelets were significantly less activated following ADP stimulation, compared to control or JAK2 mutated platelets (P < .001). In live‐cell imaging of platelet attachment to immobilized fibrinogen by Interference Reflection Microscopy (IRM), the number of attached CALR mutated platelets was lower compared to control and JAK2 mutated platelets, with lower fractions of platelets achieving the fully spread state (90%, 78% and 54% of adherent cells for control, JAK2 and CALR mutated subjects, respectively). Compared to controls, ET patients, regardless of the mutation type, had increased numbers of immature platelets (IP) and leukocyte platelet aggregates (LPA), as well as plasma sP‐selectin. These were all correlated with the platelet count and not to the state of platelet activation. We also found that intracellular free Ca2+ was increased in resting ET compared to control platelets. Note, CALR had a more dispersed localization in activated ET platelets compared to healthy controls, and mutated CALR interact physically with TpoR in CALR mutated platelets. We hypothesize that defects in platelet activation and spreading in CALR mutated patients can explain, at least in part, the lower thrombotic tendency in CALR mutated ET patients.
From the Clinical Research Center, Thrombosis and Hemostasis Research Group of the Hungarian Academy of Sciences (GL, ZBe, LM) and 2nd Department of Medicine, Thrombosis and Hemostasis Division (ZBo) ...and Department of Biophysics and Cell Biology (GV) and Department of Clinical Biochemistry and Molecular Pathology (JK), University of Debrecen, Medical and Health Science Center, Debrecen, Hungary; Amalia Biron Research Institute of Thrombosis and Hemostasis, The Chaim Sheba Medical Center, Tel-Hashomer, Israel (NR, HH)
Correspondence: László Muszbek, MD, PhD, Clinical Research Center, University of Debrecen, Medical and Health Science Center, PO Box 40, Debrecen 4012, Hungary. E-mail: muszbek{at}med.unideb.hu
In the platelets of a type II Glanzmann thrombasthenia patient, the amount of glycoprotein (GP) IIb and IIIa was significantly reduced. Three novel mutations were identified in the GPIIb gene (c.440C G/p.Leu116Val, c.1772_1773insG/p.Asp560 GlyfsX16 and c.2438C A/p.His782Asn). p.Leu116Val did not represent a causative mutation. The c.1772_1773insG mutation resulted in an early stop codon and nonsense mediated decay of mRNA. When expressed in transfected BHK cells, the truncated protein was unable to form complex with GPIIIa. The p.His782Asn mutation compromised transport of the pro-GPIIb/IIIa complex from the endoplasmic reticulum to the Golgi, hindering its maturation and surface expression.
Key words: fibrinogen receptor, Glanzmann thrombasthenia, glycoprotein IIb mutations.
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