Pathophysiology of β2-glycoprotein I in antiphospholipid syndrome

Lupus ◽  
2010 ◽  
Vol 19 (4) ◽  
pp. 379-384 ◽  
Author(s):  
E. Matsuura ◽  
L. Shen ◽  
Y. Matsunami ◽  
N. Quan ◽  
M. Makarova ◽  
...  
Keyword(s):  
Vascular Disease ◽  
Antiphospholipid Syndrome ◽  
Mechanism Of Action ◽  
Antiphospholipid Antibodies ◽  
Physiological Role ◽  
Therapeutic Strategies ◽  
Physiological Functions ◽  
Glycoprotein I ◽  
The Impact

Since β2-glycoprotein I (β2GPI) was described as the major antigenic target for antiphospholipid antibodies, many studies have focused their attention to the physiological role of β2GPI and anti-β2GPI antibodies on autoimmune-mediated thrombosis. Studies reporting the physiological role of β2GPI have been numerous, but the exact mechanism of action(s) has yet to be completely determined. β2GPI’s epitopes for anti-β2GPI autoantibodies have been characterized, however, not all of the heterogeneous anti-β2GPI antibodies are pathogenic. The pathophysiologic role of β2GPI has been reported in the fields of coagulation, fibrinolysis, angiogenesis, and atherosclerosis. Our understanding of the impact of β2GPI, its metabolites and autoantibodies to β2GPI on these physiological functions may contribute to the development of better therapeutic strategies to treat and prevent autoimmune-mediated atherothrombotic vascular disease. Lupus (2010) 19, 379—384.

Phagocytosis of platelet microvesicles and β2– glycoprotein I

2010 ◽  
Vol 104 (08) ◽  
pp. 335-341 ◽  
Author(s):  
Anhquyen Le ◽  
Anthony Prakasam ◽  
Hanan Abdel-Monem ◽  
Swapan Dasgupta ◽  
Perumal Thiagarajan
Keyword(s):  
Antiphospholipid Syndrome ◽  
Antiphospholipid Antibodies ◽  
Binding Capacity ◽  
Plasma Concentrations ◽  
Physiological Role ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Phospholipid Binding ◽  
Glycoprotein I

SummaryThe majority of the antiphospholipid antibodies, present in patients with antiphospholipid syndrome, are directed against conformational epitopes in β2-glycoprotein I. β2-glycoprotein I is an anionic phospholipid- binding 50-kDa plasma protein whose physiological role is not clear. Here we investigate the role of β2-glycoprotein I in the phagocytosis of phosphatidylserine-expressing platelet microvesicles and the effect of autoantibodies to β2-glycoprotein I on this process. We labelled the glycans of β2-glycoprotein I with BODIPY (4,4-difluoro- 4-bora-3a,4a-diaza-s-indacene)-hydrazide without affecting its phospholipid binding capacity. BODIPY-β2-glycoprotein I bound to platelet microvesicles in a concentration-dependent manner and promoted the phagocytosis of platelet microvesicles by THP-1 derived macrophages in vitro at physiological plasma concentrations with a half maximal effect at ∼10 μg/ml. β2-glycoprotein I-stimulated phagocytosis was inhibited by annexin A5 and the phosphatidylserine-binding C1C2 fragment of lactadherin. Furthermore, immunoaffinity purified β2-glycoprotein I-dependent antiphospholipid antibodies from five patients with antiphospholipid syndrome inhibited the phagocytosis in a concentration- dependent manner. These studies suggest that the binding of β2-glycoprotein I to phosphatidylserine-expressing procoagulant platelet microvesicles may promote their clearance by phagocytosis and autoantibodies to β2-glycoprotein I may inhibit this process to induce a procoagulant state.

scholarly journals Pediatric Antiphospholipid Syndrome: from Pathogenesis to Clinical Management

2021 ◽  
Vol 23 (2) ◽  
Author(s):  
Silvia Rosina ◽  
Cecilia Beatrice Chighizola ◽  
Angelo Ravelli ◽  
Rolando Cimaz
Keyword(s):  
Antiphospholipid Syndrome ◽  
Fluid Phase ◽  
Multiple Organ ◽  
Clinical Settings ◽  
Glycoprotein I ◽  
Long Term Follow Up ◽  
Pediatric Populations ◽  
Cellular Components

Abstract Purpose of Review Elucidating the pathogenic mechanisms mediated by antiphospholipid antibodies (aPL) might exert important clinical implications in pediatric antiphospholipid syndrome (APS). Recent Findings aPL are traditionally regarded as the main pathogenic players in APS, inducing thrombosis via the interaction with fluid-phase and cellular components of coagulation. Recent APS research has focused on the role of β2 glycoprotein I, which bridges innate immunity and coagulation. In pediatric populations, aPL should be screened in appropriate clinical settings, such as thrombosis, multiple-organ dysfunction, or concomitant systemic autoimmune diseases. Children positive for aPL tests often present non-thrombotic non-criteria manifestations or asymptomatic aPL positivity. In utero aPL exposure has been suggested to result in developmental disabilities, warranting long-term follow-up. Summary The knowledge of the multifaceted nature of pediatric APS should be implemented to reduce the risk of underdiagnosing/undertreating this condition. Hopefully, recent pathogenic insights will open new windows of opportunity in the management of pediatric APS.

scholarly journals Interphotoreceptor coupling: an evolutionary perspective

2021 ◽  
Author(s):  
Lorenzo Cangiano ◽  
Sabrina Asteriti
Keyword(s):  
Visual Information ◽  
Signal To Noise Ratio ◽  
Electrical Coupling ◽  
Physiological Role ◽  
Cellular Processes ◽  
Contact Points ◽  
Highly Sensitive ◽  
The Many ◽  
The Impact

AbstractIn the vertebrate retina, signals generated by cones of different spectral preference and by highly sensitive rod photoreceptors interact at various levels to extract salient visual information. The first opportunity for such interaction is offered by electrical coupling of the photoreceptors themselves, which is mediated by gap junctions located at the contact points of specialised cellular processes: synaptic terminals, telodendria and radial fins. Here, we examine the evolutionary pressures for and against interphotoreceptor coupling, which are likely to have shaped how coupling is deployed in different species. The impact of coupling on signal to noise ratio, spatial acuity, contrast sensitivity, absolute and increment threshold, retinal signal flow and colour discrimination is discussed while emphasising available data from a variety of vertebrate models spanning from lampreys to primates. We highlight the many gaps in our knowledge, persisting discrepancies in the literature, as well as some major unanswered questions on the actual extent and physiological role of cone-cone, rod-cone and rod-rod communication. Lastly, we point toward limited but intriguing evidence suggestive of the ancestral form of coupling among ciliary photoreceptors.

scholarly journals Role of Tissue Factor in the Pathogenesis of COVID-19 and the Possible Ways to Inhibit It

2021 ◽  
Vol 27 ◽  
pp. 107602962110039
Author(s):  
Carlos A. Cañas ◽  
Felipe Cañas ◽  
Mario Bautista-Vargas ◽  
Fabio Bonilla-Abadía
Keyword(s):  
Tissue Factor ◽  
Proinflammatory Cytokines ◽  
Antiphospholipid Antibodies ◽  
Therapeutic Strategies ◽  
Prothrombotic State ◽  
Pulmonary Epithelium ◽  
Angiotensin Converting Enzyme 2 ◽  
Patients With Heart Failure ◽  
Inflammatory Effect

COVID-19 (Coronavirus Disease 2019) is a highly contagious infection and associated with high mortality rates, primarily in elderly; patients with heart failure; high blood pressure; diabetes mellitus; and those who are smokers. These conditions are associated to increase in the level of the pulmonary epithelium expression of angiotensin-converting enzyme 2 (ACE-2), which is a recognized receptor of the S protein of the causative agent SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2). Severe cases are manifested by parenchymal lung involvement with a significant inflammatory response and the development of microvascular thrombosis. Several factors have been involved in developing this prothrombotic state, including the inflammatory reaction itself with the participation of proinflammatory cytokines, endothelial dysfunction/endotheliitis, the presence of antiphospholipid antibodies, and possibly the tissue factor (TF) overexpression. ARS-Cov-19 ACE-2 down-regulation has been associated with an increase in angiotensin 2 (AT2). The action of proinflammatory cytokines, the increase in AT2 and the presence of antiphospholipid antibodies are known factors for TF activation and overexpression. It is very likely that the overexpression of TF in COVID-19 may be related to the pathogenesis of the disease, hence the importance of knowing the aspects related to this protein and the therapeutic strategies that can be derived. Different therapeutic strategies are being built to curb the expression of TF as a therapeutic target for various prothrombotic events; therefore, analyzing this treatment strategy for COVID-19-associated coagulopathy is rational. Medications such as celecoxib, cyclosporine or colchicine can impact on COVID-19, in addition to its anti-inflammatory effect, through inhibition of TF.

scholarly journals Therapeutic Value of Single Nucleotide Polymorphisms on the Efficacy of New Therapies in Patients with Multiple Sclerosis

2021 ◽  
Vol 11 (5) ◽  
pp. 335
Author(s):  
María José Zarzuelo Romero ◽  
Cristina Pérez Ramírez ◽  
María Isabel Carrasco Campos ◽  
Almudena Sánchez Martín ◽  
Miguel Ángel Calleja Hernández ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Mechanism Of Action ◽  
Dimethyl Fumarate ◽  
Response To Treatment ◽  
Nucleotide Polymorphisms ◽  
New Therapies ◽  
Therapeutic Value ◽  
The Impact

The introduction of new therapies for the treatment of multiple sclerosis (MS) is a very recent phenomenon and little is known of their mechanism of action. Moreover, the response is subject to interindividual variability and may be affected by genetic factors, such as polymorphisms in the genes implicated in the pathologic environment, pharmacodynamics, and metabolism of the disease or in the mechanism of action of the medications, influencing the effectiveness of these therapies. This review evaluates the impact of pharmacogenetics on the response to treatment with new therapies in patients diagnosed with MS. The results suggest that polymorphisms detected in the GSTP1, ITGA4, NQO1, AKT1, and GP6 genes, for treatment with natalizumab, ZMIZ1, for fingolimod and dimethyl fumarate, ADA, for cladribine, and NOX3, for dimethyl fumarate, may be used in the future as predictive markers of treatment response to new therapies in MS patients. However, there are few existing studies and their samples are small, making it difficult to generalize the role of these genes in treatment with new therapies. Studies with larger sample sizes and longer follow-up are therefore needed to confirm the results of these studies.

scholarly journals Immunotoxicity of Xenobiotics in Fish: A Role for the Aryl Hydrocarbon Receptor (AhR)?

2021 ◽  
Vol 22 (17) ◽  
pp. 9460
Author(s):  
Helmut Segner ◽  
Christyn Bailey ◽  
Carolina Tafalla ◽  
Jun Bo
Keyword(s):  
Immune System ◽  
Aryl Hydrocarbon Receptor ◽  
Disease Susceptibility ◽  
Immune Cell ◽  
Physiological Role ◽  
Immune Gene ◽  
Immune Systems ◽  
Aryl Hydrocarbon ◽  
The Impact

The impact of anthropogenic contaminants on the immune system of fishes is an issue of growing concern. An important xenobiotic receptor that mediates effects of chemicals, such as halogenated aromatic hydrocarbons (HAHs) and polyaromatic hydrocarbons (PAHs), is the aryl hydrocarbon receptor (AhR). Fish toxicological research has focused on the role of this receptor in xenobiotic biotransformation as well as in causing developmental, cardiac, and reproductive toxicity. However, biomedical research has unraveled an important physiological role of the AhR in the immune system, what suggests that this receptor could be involved in immunotoxic effects of environmental contaminants. The aims of the present review are to critically discuss the available knowledge on (i) the expression and possible function of the AhR in the immune systems of teleost fishes; and (ii) the impact of AhR-activating xenobiotics on the immune systems of fish at the levels of immune gene expression, immune cell proliferation and immune cell function, immune pathology, and resistance to infectious disease. The existing information indicates that the AhR is expressed in the fish immune system, but currently, we have little understanding of its physiological role. Exposure to AhR-activating contaminants results in the modulation of numerous immune structural and functional parameters of fish. Despite the diversity of fish species studied and the experimental conditions investigated, the published findings rather uniformly point to immunosuppressive actions of xenobiotic AhR ligands in fish. These effects are often associated with increased disease susceptibility. The fact that fish populations from HAH- and PAH-contaminated environments suffer immune disturbances and elevated disease susceptibility highlights that the immunotoxic effects of AhR-activating xenobiotics bear environmental relevance.

scholarly journals Molecular Mechanisms of “Antiphospholipid Antibodies” and Their Paradoxical Role in the Pathogenesis of “Seronegative APS”

2020 ◽  
Vol 21 (21) ◽  
pp. 8411
Author(s):  
Roberta Misasi ◽  
Agostina Longo ◽  
Serena Recalchi ◽  
Daniela Caissutti ◽  
Gloria Riitano ◽  
...  
Keyword(s):  
Antiphospholipid Antibodies ◽  
Molecular Mechanisms ◽  
Strong Association ◽  
Fetal Loss ◽  
Signal Transduction Pathway ◽  
Therapeutic Strategies ◽  
Transduction Pathway ◽  
Laboratory Methods ◽  
Pregnancy Morbidity ◽  
Glycoprotein I

Antiphospholipid Syndrome (APS) is an autoimmune disease characterized by arterial and/or venous thrombosis and/or pregnancy morbidity, associated with circulating antiphospholipid antibodies (aPL). In some cases, patients with a clinical profile indicative of APS (thrombosis, recurrent miscarriages or fetal loss), who are persistently negative for conventional laboratory diagnostic criteria, are classified as “seronegative” APS patients (SN-APS). Several findings suggest that aPL, which target phospholipids and/or phospholipid binding proteins, mainly β-glycoprotein I (β-GPI), may contribute to thrombotic diathesis by interfering with hemostasis. Despite the strong association between aPL and thrombosis, the exact pathogenic mechanisms underlying thrombotic events and pregnancy morbidity in APS have not yet been fully elucidated and multiple mechanisms may be involved. Furthermore, in many SN-APS patients, it is possible to demonstrate the presence of unconventional aPL (“non-criteria” aPL) or to detect aPL with alternative laboratory methods. These findings allowed the scientists to study the pathogenic mechanism of SN-APS. This review is focused on the evidence showing that these antibodies may play a functional role in the signal transduction pathway(s) leading to thrombosis and pregnancy morbidity in SN-APS. A better comprehension of the molecular mechanisms triggered by aPL may drive development of potential therapeutic strategies in APS patients.

scholarly journals Molecular Hydrogen, a Neglected Key Driver of Soil Biogeochemical Processes

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Sarah Piché-Choquette ◽  
Philippe Constant
Keyword(s):  
Energy Requirement ◽  
Keystone Species ◽  
Physiological Role ◽  
Atp Synthesis ◽  
Potential Contribution ◽  
Biogeochemical Processes ◽  
Individual Level ◽  
C Cycling ◽  
The Impact

ABSTRACTThe atmosphere of the early Earth is hypothesized to have been rich in reducing gases such as hydrogen (H2). H2has been proposed as the first electron donor leading to ATP synthesis due to its ubiquity throughout the biosphere as well as its ability to easily diffuse through microbial cells and its low activation energy requirement. Even today, hydrogenase enzymes enabling the production and oxidation of H2are found in thousands of genomes spanning the three domains of life across aquatic, terrestrial, and even host-associated ecosystems. Even though H2has already been proposed as a universal growth and maintenance energy source, its potential contribution as a driver of biogeochemical cycles has received little attention. Here, we bridge this knowledge gap by providing an overview of the classification, distribution, and physiological role of hydrogenases. Distribution of these enzymes in various microbial functional groups and recent experimental evidence are finally integrated to support the hypothesis that H2-oxidizing microbes are keystone species driving C cycling along O2concentration gradients found in H2-rich soil ecosystems. In conclusion, we suggest focusing on the metabolic flexibility of H2-oxidizing microbes by combining community-level and individual-level approaches aiming to decipher the impact of H2on C cycling and the C-cycling potential of H2-oxidizing microbes, via both culture-dependent and culture-independent methods, to give us more insight into the role of H2as a driver of biogeochemical processes.

β2-Glycoprotein I: Target antigen for ‘antiphospholipid’ antibodies. Immunological and molecular aspects

Lupus ◽  
1998 ◽  
Vol 7 (2_suppl) ◽  
pp. 5-9 ◽  
Author(s):  
Y Sheng ◽  
DA Kandiah ◽  
SA Krilis
Keyword(s):  
Antiphospholipid Syndrome ◽  
Antiphospholipid Antibodies ◽  
Fluid Phase ◽  
Target Antigen ◽  
Phospholipid Membranes ◽  
Anionic Phospholipid ◽  
Glycoprotein I ◽  
High Concentrations ◽  
Molecular Aspects ◽  
Anionic Phospholipid Membranes

It has become clear that β2-glycoprotein I (β2GPI) is the most common and best-characterised antigenic target for ‘antiphospholipid’ (aPL) autoantibodies. These antibodies preferentially bind β2GPI that has been immobilised on anionic phospholipid membranes or certain synthetic surfaces. These surfaces appear to act by increasing antigen density to allow binding of intrinsically low-affinity anti-β2GPI autoantibodies. Binding of β2GPI in fluid phase is weak and requires high concentrations of β2GPI. Our understanding of the pathophysiology of the ‘Antiphospholipid’ Syndrome (APS) has increased exponentially with the number of studies into the interactions of aPL antibodies and β2GPI.

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