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Arteriosclerosis, Thrombosis, and... Aug 2023MAGT1 (magnesium transporter 1) is a subunit of the oligosaccharide protein complex with thiol-disulfide oxidoreductase activity, supporting the process of...
BACKGROUND
MAGT1 (magnesium transporter 1) is a subunit of the oligosaccharide protein complex with thiol-disulfide oxidoreductase activity, supporting the process of N-glycosylation. MAGT1 deficiency was detected in human patients with X-linked immunodeficiency with magnesium defect syndrome and congenital disorders of glycosylation, resulting in decreased cation responses in lymphocytes, thereby inhibiting the immune response against viral infections. Curative hematopoietic stem cell transplantation of patients with X-linked immunodeficiency with magnesium defect causes fatal bleeding and thrombotic complications.
METHODS
We studied the role of MAGT1 deficiency in platelet function in relation to arterial thrombosis and hemostasis using several in vitro experimental settings and in vivo models of arterial thrombosis and transient middle cerebral artery occlusion model of ischemic stroke.
RESULTS
MAGT1-deficient mice () displayed accelerated occlusive arterial thrombus formation in vivo, a shortened bleeding time, and profound brain damage upon focal cerebral ischemia. These defects resulted in increased calcium influx and enhanced second wave mediator release, which further reinforced platelet reactivity and aggregation responses. Supplementation of MgCl or pharmacological blockade of TRPC6 (transient receptor potential cation channel, subfamily C, member 6) channel, but not inhibition of store-operated calcium entry, normalized the aggregation responses of platelets to the control level. GP (glycoprotein) VI activation of platelets resulted in hyperphosphorylation of Syk (spleen tyrosine kinase), LAT (linker for activation of T cells), and PLC (phospholipase C) γ2, whereas the inhibitory loop regulated by PKC (protein kinase C) was impaired. A hyperaggregation response to the GPVI agonist was confirmed in human platelets isolated from a MAGT1-deficient (X-linked immunodeficiency with magnesium defect) patient. Haploinsufficiency of TRPC6 in mice could normalize GPVI signaling, platelet aggregation, and thrombus formation in vivo.
CONCLUSIONS
These results suggest that MAGT1 and TRPC6 are functionally linked. Therefore, deficiency or impaired functionality of MAGT1 could be a potential risk factor for arterial thrombosis and stroke.
Topics: Animals; Humans; Mice; Blood Platelets; Calcium; Cations; Homeostasis; Ischemic Stroke; Magnesium; Platelet Activation; Platelet Aggregation; Platelet Membrane Glycoproteins; Thrombosis; TRPC6 Cation Channel; Infarction, Middle Cerebral Artery; Cation Transport Proteins
PubMed: 37381987
DOI: 10.1161/ATVBAHA.122.318115 -
Platelets Dec 2023The anucleate human platelets contain a broad pattern of mRNAs and other RNA transcripts. The high quantitative similarity of mRNAs in megakaryocytes and platelets from... (Review)
Review
The anucleate human platelets contain a broad pattern of mRNAs and other RNA transcripts. The high quantitative similarity of mRNAs in megakaryocytes and platelets from different sources points to a common origin, and suggests a random redistribution of mRNA species upon proplatelet formation. A comparison of the classified platelet transcriptome (17.6k transcripts) with the identified platelet proteome (5.2k proteins) indicates an under-representation of: nuclear but not of other organellar proteins; membrane receptors and channels with low transcript levels; transcription/translation proteins; and so far uncharacterized proteins. In this review, we discuss the technical, normalization and database-dependent possibilities and challenges to come to a complete, genome-wide platelet transcriptome and proteome. Such a reference transcriptome and proteome can serve to further elucidate intra-subject and inter-subject differences in platelets in health and disease. Applications may also lay in the aid of genetic diagnostics.
Topics: Humans; Proteome; Blood Platelets; Transcriptome; Megakaryocytes; Databases, Factual; RNA, Messenger
PubMed: 37313659
DOI: 10.1080/09537104.2023.2224454 -
International Journal of Molecular... May 2024Platelets play an important role in hemostasis, and a low platelet count usually increases the risk of bleeding. Conditions in which thrombosis occurs despite low... (Review)
Review
Platelets play an important role in hemostasis, and a low platelet count usually increases the risk of bleeding. Conditions in which thrombosis occurs despite low platelet counts are referred to as thrombosis with thrombocytopenia syndrome, including heparin-induced thrombocytopenia, vaccine-induced immune thrombotic thrombocytopenia, paroxysmal nocturnal hemoglobinuria, antiphospholipid syndrome, thrombotic microangiopathy (TMA), and disseminated intravascular coagulation. TMA includes thrombotic thrombocytopenic purpura, Shiga toxin-producing -associated hemolytic uremic syndrome (HUS), and atypical HUS. Patients with these pathologies present with thrombosis and consumptive thrombocytopenia associated with the activation of platelets and the coagulation system. Treatment varies from disease to disease, and many diseases have direct impacts on mortality and organ prognosis if therapeutic interventions are not promptly implemented. Underlying diseases and the results of physical examinations and general laboratory tests as part of a thorough workup for patients should promptly lead to therapeutic intervention before definitive diagnosis. For some diseases, the diagnosis and initial treatment must proceed in parallel. Utilization of not only laboratory tests but also various scoring systems is important for validating therapeutic interventions based on clinical information.
Topics: Humans; Thrombocytopenia; Thrombosis; Blood Platelets; Platelet Count; Heparin; Thrombotic Microangiopathies
PubMed: 38732176
DOI: 10.3390/ijms25094956 -
Hamostaseologie Feb 2024Inflammation and thrombosis are intricate and closely interconnected biological processes that are not yet fully understood and lack effective targeted therapeutic... (Review)
Review
Inflammation and thrombosis are intricate and closely interconnected biological processes that are not yet fully understood and lack effective targeted therapeutic approaches. Thrombosis initiated by inflammatory responses, known as immunothrombosis, can confer advantages to the host by constraining the spread of pathogens within the bloodstream. Conversely, platelets and the coagulation cascade can influence inflammatory responses through interactions with immune cells, endothelium, or complement system. These interactions can lead to a state of heightened inflammation resulting from thrombotic processes, termed as thromboinflammation. This review aims to comprehensively summarize the existing knowledge of thromboinflammation and addressing its significance as a challenging clinical issue.
Topics: Humans; Thrombosis; Inflammation; Thromboinflammation; Blood Coagulation; Blood Platelets
PubMed: 38417802
DOI: 10.1055/a-2178-6491 -
Platelets Dec 2023Proteomics tools provide a powerful means to identify, detect, and quantify protein-related details in studies of platelet phenotype and function. Here, we consider how...
Proteomics tools provide a powerful means to identify, detect, and quantify protein-related details in studies of platelet phenotype and function. Here, we consider how historical and recent advances in proteomics approaches have informed our understanding of platelet biology, and, how proteomics tools can be used going forward to advance studies of platelets. It is now apparent that the platelet proteome is comprised of thousands of different proteins, where specific changes in platelet protein systems can accompany alterations in platelet function in health and disease. Going forward, many challenges remain in how to best carry out, validate and interpret platelet proteomics experiments. Future studies of platelet protein post-translational modifications such as glycosylation, or studies that take advantage of single cell proteomics and top-down proteomics methods all represent areas of interest to profiling and more richly understanding platelets in human wellness and disease.
Topics: Humans; Blood Platelets; Proteomics; Phenotype; Proteome
PubMed: 37246523
DOI: 10.1080/09537104.2023.2217932 -
European Journal of Medical Research Sep 2023Platelets play a crucial role in cancer blood metastasis. Various cancer-related factors such as Toll-like receptors (TLRs), adenosine diphosphate (ADP) or extracellular... (Review)
Review
Platelets play a crucial role in cancer blood metastasis. Various cancer-related factors such as Toll-like receptors (TLRs), adenosine diphosphate (ADP) or extracellular matrix (ECM) can activate these small particles that function in hemostasis and thrombosis. Moreover, platelets induce Epithelial Mesenchymal Transition (EMT) to promote cancer progression and invasiveness. The activated platelets protect circulating tumor cells from immune surveillance and anoikis. They also mediate tumor cell arrest, extravasation and angiogenesis in distant organs through direct or indirect modulation, creating a metastatic microenvironment. This review summarizes the recent advances and progress of mechanisms in platelet activation and its interaction with cancer cells in metastasis.
Topics: Humans; Neoplasms; Blood Platelets; Neoplasm Metastasis; Tumor Microenvironment
PubMed: 37770941
DOI: 10.1186/s40001-023-01342-w -
Biomolecules Nov 2023Platelets are anucleate cytoplasmic cell fragments that circulate in the blood, where they are involved in regulating hemostasis. Beyond their normal physiologic role,... (Review)
Review
Platelets are anucleate cytoplasmic cell fragments that circulate in the blood, where they are involved in regulating hemostasis. Beyond their normal physiologic role, platelets have emerged as versatile effectors of immune response. During an infection, cell surface receptors enable platelets to recognize viruses, resulting in their activation. Activated platelets release biologically active molecules that further trigger host immune responses to protect the body against infection. Their impact on the immune response is also associated with the recruitment of circulating leukocytes to the site of infection. They can also aggregate with leukocytes, including lymphocytes, monocytes, and neutrophils, to immobilize pathogens and prevent viral dissemination. Despite their host protective role, platelets have also been shown to be associated with various pathophysiological processes. In this review, we will summarize platelet and HIV interactions during infection. We will also highlight and discuss platelet and platelet-derived mediators, how they interact with immune cells, and the multifaceted responsibilities of platelets in HIV infection. Furthermore, we will give an overview of non-AIDS comorbidities linked to platelet dysfunction and the impact of antiretroviral therapy on platelet function.
Topics: Humans; HIV Infections; Inflammation; Blood Platelets; Hemostasis; Leukocytes
PubMed: 38002289
DOI: 10.3390/biom13111608 -
Blood Jan 2024Platelet factor 4 (PF4) is an abundant chemokine that is released from platelet α-granules on activation. PF4 is central to the pathophysiology of vaccine-induced...
Platelet factor 4 (PF4) is an abundant chemokine that is released from platelet α-granules on activation. PF4 is central to the pathophysiology of vaccine-induced immune thrombocytopenia and thrombosis (VITT) in which antibodies to PF4 form immune complexes with PF4, which activate platelets and neutrophils through Fc receptors. In this study, we show that PF4 binds and activates the thrombopoietin receptor, cellular myeloproliferative leukemia protein (c-Mpl), on platelets. This leads to the activation of Janus kinase 2 (JAK2) and phosphorylation of signal transducer and activator of transcription (STAT) 3 and STAT5, leading to platelet aggregation. Inhibition of the c-Mpl-JAK2 pathway inhibits platelet aggregation to PF4, VITT sera, and the combination of PF4 and IgG isolated from VITT patient plasma. The results support a model in which PF4-based immune complexes activate platelets through binding of the Fc domain to FcγRIIA and PF4 to c-Mpl.
Topics: Humans; Antigen-Antibody Complex; Blood Platelets; Heparin; Immunologic Factors; Janus Kinase 2; Platelet Factor 4; Receptors, Thrombopoietin; Thrombocytopenia
PubMed: 37883794
DOI: 10.1182/blood.2023020872 -
International Journal of Molecular... Aug 2023Thrombocytes are numerous in the blood of aves (birds) and ichthyoids (fish). The origin of this cell type is a common hematopoietic stem cell giving rise to a cell that... (Review)
Review
Thrombocytes are numerous in the blood of aves (birds) and ichthyoids (fish). The origin of this cell type is a common hematopoietic stem cell giving rise to a cell that is active in blood coagulation, inflammatory functions, and the immune response in general. It has been well documented that thrombocytes can phagocytize small particles and bacteria. While phagocytosis with an associated oxidative burst has been reported for chicken thrombocytes, some questions remain as to the degradation capacity of phagosomes in ichthyoids. As innate cells, thrombocytes can be stimulated by bacterial, viral, and fungal pathogens to express altered gene expression. Furthermore, there have been observations that led researchers to state that platelets/thrombocytes are capable of serving as "professional antigen presenting cells" expressing CD40, CD80/86, MHC I, and MHC II. This indeed may be the case or, more likely at this time, provide supporting evidence that these cells aid and assist in the role of professional antigen-presenting cells to initiate adaptive immune responses.
Topics: Animals; Blood Platelets; Blood Coagulation; Antigen-Presenting Cells; B7-1 Antigen; Bacteriophages
PubMed: 37629130
DOI: 10.3390/ijms241612950 -
Platelets Dec 2023Inherited thrombocytopenia (IT) is a group of hereditary disorders characterized by a reduced platelet count as the main clinical manifestation, and often with abnormal... (Review)
Review
Inherited thrombocytopenia (IT) is a group of hereditary disorders characterized by a reduced platelet count as the main clinical manifestation, and often with abnormal platelet function, which can subsequently lead to impaired hemostasis. In the past decades, humanized mouse models (HMMs), that are mice engrafted with human cells or genes, have been widely used in different research areas including immunology, oncology, and virology. With advances of the development of immunodeficient mice, the engraftment, and reconstitution of functional human platelets in HMM permit studies of occurrence and development of platelet disorders including IT and treatment strategies. This article mainly reviews the development of humanized mice models, the construction methods, research status, and problems of using humanized mice for the study of human thrombopoiesis.
Topics: Animals; Mice; Humans; Disease Models, Animal; Blood Platelets; Thrombopoiesis; Thrombocytopenia; Blood Platelet Disorders; Hematopoietic Stem Cell Transplantation
PubMed: 37849076
DOI: 10.1080/09537104.2023.2267676