Identification of critical antigen-specific mechanisms in the development of immune thrombocytopenic purpura in mice

Blood ◽  
2000 ◽  
Vol 96 (7) ◽  
pp. 2520-2527 ◽  
Author(s):  
Bernhard Nieswandt ◽  
Wolfgang Bergmeier ◽  
Kirsten Rackebrandt ◽  
J. Engelbert Gessner ◽  
Hubert Zirngibl
Keyword(s):  
Platelet Activating Factor ◽  
Target Antigen ◽  
Transient Effects ◽  
Platelet Destruction ◽  
Spontaneous Bleeding ◽  
Antiplatelet Antibodies ◽  
Systemic Reactions ◽  
Linear Epitopes ◽  
Immunoglobulin G Subclass

Abstract The pathogenic effects of antiplatelet antibodies were investigated in mice. Monoclonal antibodies (mAbs) of different immunoglobulin G subclass directed against mouse GPIIbIIIa, GPIIIa, GPIbα, GPIb-IX, GPV, and CD31 were generated and characterized biochemically. MAbs against GPIb-IX, GPV, CD31, and linear epitopes on GPIIIa had mild and transient effects on platelet counts and induced no spontaneous bleeding. Anti-GPIbα mAbs induced profound irreversible thrombocytopenia (< 3% of normal) by Fc-independent mechanisms but only had minor effects on hematocrits. In contrast, injection of intact mAbs, but not F(ab)2 fragments, against conformational epitopes on GPIIbIIIa, induced irreversible thrombocytopenia, acute systemic reactions, hypothermia, decreased hematocrits, and a paradoxical loss of surface GPIIbIIIa on platelets in vivo, the latter suggesting the formation of platelet-derived microparticles. Blockage of platelet-activating factor receptors inhibited the acute reactions, but not thrombocytopenia, loss of GPIIbIIIa, and decreases in hematocrits. Repeated injections of low doses of anti-GPIIbIIIa antibodies resulted in profound thrombocytopenia and bleeding, whereas no acute systemic reactions were observed. These data strongly suggest that the identity of the target antigen recognized by antiplatelet antibodies determines the mechanisms of platelet destruction and the severity of bleeding in mice, the latter depending on previously unrecognized anti-GPIIbIIIa-specific inflammatory mechanisms.

Identification of critical antigen-specific mechanisms in the development of immune thrombocytopenic purpura in mice

Blood ◽  
2000 ◽  
Vol 96 (7) ◽  
pp. 2520-2527 ◽  
Author(s):  
Bernhard Nieswandt ◽  
Wolfgang Bergmeier ◽  
Kirsten Rackebrandt ◽  
J. Engelbert Gessner ◽  
Hubert Zirngibl
Keyword(s):  
Platelet Activating Factor ◽  
Target Antigen ◽  
Transient Effects ◽  
Platelet Destruction ◽  
Spontaneous Bleeding ◽  
Antiplatelet Antibodies ◽  
Systemic Reactions ◽  
Linear Epitopes ◽  
Immunoglobulin G Subclass

The pathogenic effects of antiplatelet antibodies were investigated in mice. Monoclonal antibodies (mAbs) of different immunoglobulin G subclass directed against mouse GPIIbIIIa, GPIIIa, GPIbα, GPIb-IX, GPV, and CD31 were generated and characterized biochemically. MAbs against GPIb-IX, GPV, CD31, and linear epitopes on GPIIIa had mild and transient effects on platelet counts and induced no spontaneous bleeding. Anti-GPIbα mAbs induced profound irreversible thrombocytopenia (< 3% of normal) by Fc-independent mechanisms but only had minor effects on hematocrits. In contrast, injection of intact mAbs, but not F(ab)2 fragments, against conformational epitopes on GPIIbIIIa, induced irreversible thrombocytopenia, acute systemic reactions, hypothermia, decreased hematocrits, and a paradoxical loss of surface GPIIbIIIa on platelets in vivo, the latter suggesting the formation of platelet-derived microparticles. Blockage of platelet-activating factor receptors inhibited the acute reactions, but not thrombocytopenia, loss of GPIIbIIIa, and decreases in hematocrits. Repeated injections of low doses of anti-GPIIbIIIa antibodies resulted in profound thrombocytopenia and bleeding, whereas no acute systemic reactions were observed. These data strongly suggest that the identity of the target antigen recognized by antiplatelet antibodies determines the mechanisms of platelet destruction and the severity of bleeding in mice, the latter depending on previously unrecognized anti-GPIIbIIIa-specific inflammatory mechanisms.

HETEROGENEITY OF MEGAKARYOCYTE PLOIDY PROFILE IN PATIENTS WITH ITP

1987 ◽  
Author(s):  
J Bussel ◽  
E Rabellino
Keyword(s):  
Treatment Strategies ◽  
Severe Form ◽  
Platelet Glycoprotein ◽  
Target Antigen ◽  
Platelet Response ◽  
Platelet Destruction ◽  
Platelet Production ◽  
Group Iii ◽  
Antiplatelet Antibodies ◽  
Group I

Thrombocytopenia in patients with ITP is ascribed to peripheral platelet destruction mediated by antiplatelet antibodies. Patients with a chronic severe form of disease may also have im paired platelet production. Profile of DNA content and distribu tion in marrow megakaryocytes (MK) is a sensitive parameter of megakaryocyte development. In these studies MK derived from clinical aspirates were analyzed by flow cytometry for DMA content and platelet glycoprotein GP IIb/IIIa. Both whole unsenar-ated and MK-enriched marrow were stained using double label staining for GP IIb-IIIa by immunofluorescence (green) and for DNA with propidium iodide (red). 3 different profiles were seen in ITP patients as indicated in the Table:Profile I represented the commonest pattern and was identical to that seen in normals. Profiles II and III demonstrated peak ploidy values of 8C and a bimodal 2C/16C pattern respectively. In order to investigate the relationship of ploidy profile to platelet production, we compared the peak platelet response to IVGG, a treatment which stops platelet destruction, among the 3 groups. The average platelet response to IVGG was 221,000/ul for group I, much greater than both group II (119k) and group III (96k)(I vs II + III, p < 0.05). Heterogeneity of clinical cases of ITP may be caused by differences in ploidy profile of patient marrow megakaryocytes.These profiles may be caused by a heterogeneity of the target antigen of the antiplatelet antibodies in different patients with differing crossreactivity to and effects on megakaryocytes. This heterogeneity appears to be reflected in different responses to therapies suggesting that it may be useful in designing treatment strategies.

PAF increases vascular permeability without increasing pulmonary arterial pressure in the rat

2001 ◽  
Vol 90 (1) ◽  
pp. 261-268 ◽  
Author(s):  
Leonardo C. Clavijo ◽  
Mary B. Carter ◽  
Paul J. Matheson ◽  
Mark A. Wilson ◽  
William B. Wead ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Edema ◽  
Pulmonary Arterial Pressure ◽  
Ex Vivo ◽  
Platelet Activating Factor ◽  
Microvascular Permeability ◽  
Blue Dye ◽  
E Coli ◽  
Pulmonary Arterial

In vivo pulmonary arterial catheterization was used to determine the mechanism by which platelet-activating factor (PAF) produces pulmonary edema in rats. PAF induces pulmonary edema by increasing pulmonary microvascular permeability (PMP) without changing the pulmonary pressure gradient. Rats were cannulated for measurement of pulmonary arterial pressure (Ppa) and mean arterial pressure. PMP was determined by using either in vivo fluorescent videomicroscopy or the ex vivo Evans blue dye technique. WEB 2086 was administered intravenously (IV) to antagonize specific PAF effects. Three experiments were performed: 1) IV PAF, 2) topical PAF, and 3) Escherichia coli bacteremia. IV PAF induced systemic hypotension with a decrease in Ppa. PMP increased after IV PAF in a dose-related manner. Topical PAF increased PMP but decreased Ppa only at high doses. Both PMP (88 ± 5%) and Ppa (50 ± 3%) increased during E. coli bacteremia. PAF-receptor blockade prevents changes in Ppa and PMP after both topical PAF and E. coli bacteremia. PAF, which has been shown to mediate pulmonary edema in prior studies, appears to act in the lung by primarily increasing microvascular permeability. The presence of PAF might be prerequisite for pulmonary vascular constriction during gram-negative bacteremia.

scholarly journals Hexapod Assassins’ Potion: Venom Composition and Bioactivity from the Eurasian Assassin Bug Rhynocoris iracundus

Biomedicines ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 819
Author(s):  
Nicolai Rügen ◽  
Timothy P. Jenkins ◽  
Natalie Wielsch ◽  
Heiko Vogel ◽  
Benjamin-Florian Hempel ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Galleria Mellonella ◽  
Systemic Reactions ◽  
Venom Composition ◽  
Assassin Bug ◽  
Molecular Components ◽  
First Time ◽  
Tissue Digestion

Assassin bug venoms are potent and exert diverse biological functions, making them potential biomedical goldmines. Besides feeding functions on arthropods, assassin bugs also use their venom for defense purposes causing localized and systemic reactions in vertebrates. However, assassin bug venoms remain poorly characterized. We collected the venom from the assassin bug Rhynocoris iracundus and investigated its composition and bioactivity in vitro and in vivo. It caused lysis of murine neuroblastoma, hepatoma cells, and healthy murine myoblasts. We demonstrated, for the first time, that assassin bug venom induces neurolysis and suggest that it counteracts paralysis locally via the destruction of neural networks, contributing to tissue digestion. Furthermore, the venom caused paralysis and melanization of Galleria mellonella larvae and pupae, whilst also possessing specific antibacterial activity against Escherichia coli, but not Listeria grayi and Pseudomonas aeruginosa. A combinatorial proteo-transcriptomic approach was performed to identify potential toxins responsible for the observed effects. We identified neurotoxic Ptu1, an inhibitory cystin knot (ICK) toxin homologous to ω-conotoxins from cone snails, cytolytic redulysins homologous to trialysins from hematophagous kissing bugs, and pore-forming hemolysins. Additionally, chitinases and kininogens were found and may be responsible for insecticidal and cytolytic activities. We demonstrate the multifunctionality and complexity of assassin bug venom, which renders its molecular components interesting for potential biomedical applications.

scholarly journals Regulation of human neutrophil aggregation: comparable latent times, activator sensitivities, and exponential decay in aggregability for FMLP, platelet-activating factor, and leukotriene B4

Blood ◽  
1993 ◽  
Vol 82 (11) ◽  
pp. 3460-3468 ◽  
Author(s):  
YP Rochon ◽  
MM Frojmovic
Keyword(s):  
Platelet Activating Factor ◽  
Leukotriene B4 ◽  
Variable Cross ◽  
Activator Concentration ◽  
Direct Measurements ◽  
Formyl Peptide ◽  
Activated Neutrophils ◽  
Neutrophil Aggregation ◽  
Protein Kinase C Activation

Abstract We have recently described a flow cytometry technique, whose sensitivity allows direct measurements of latent times before the onset of aggregation, and of rates, maximal extents, and reversibility of aggregation (J Leuk Biol 50:434, 1991). We report here that activators which stimulate sustained cellular signaling associated with increases in intracellular calcium (ionomycin) or protein kinase C activation (phorbol myristate acetate, PMA) cause complete (> or = 98%) and irreversible neutrophil aggregation, with latent times for the onset of aggregation inversely proportional to the activator concentration. In contrast, the receptor-specific activators leukotriene B4 (LTB4), formyl peptide FMLP, and platelet-activating factor (PAF) gave only partial and reversible aggregatory responses, limited by the following similar properties: latent times of 4.5 seconds +/- 1.5 seconds, independent of activator concentration; similar concentrations for onset of aggregation (approximately 1 nmol/L) that increased over a similar broad range of activator concentration, with one-half maximal rates of aggregation at 10 nmol/L to 30 nmol/L, corresponding to reported dissociation constant values; comparable limited recruitment and spontaneous reversibility of aggregation; absence of interactivator synergism; and similar exponential decays in activated cell stickiness (refractoriness), with t1/2 = 15 to 30 seconds. Variable cross- desensitization was seen between LTB4 and FMLP depending on donor and activator concentrations. In vivo, these properties are expected to provide localization of the aggregatory response, minimizing the otherwise detrimental effects of circulating activated neutrophils.

scholarly journals Identification of Two Cross-Neutralizing Linear Epitopes within the L1 Major Capsid Protein of Human Papillomaviruses

2002 ◽  
Vol 76 (13) ◽  
pp. 6480-6486 ◽  
Author(s):  
Alba-Lucia Combita ◽  
Antoine Touzé ◽  
Latifa Bousarghin ◽  
Neil D. Christensen ◽  
Pierre Coursaget
Keyword(s):  
Neutralizing Antibodies ◽  
Polyclonal Antibodies ◽  
Human Papillomaviruses ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Linear Epitopes ◽  
Cross Neutralization ◽  
Definition Of ◽  
L1 Protein

ABSTRACT The neutralizing activities of polyclonal antibodies and monoclonal antibodies (MAbs) obtained by immunization of mice with L1 virus-like particles (VLPs) were investigated by using pseudovirion infectivity assays for human papillomavirus type 16 (HPV-16), HPV-31, HPV-33, HPV-45, HPV-58, and HPV-59 to obtain a better definition of cross-neutralization between high-risk HPVs. In this study, we confirmed and extended previous studies indicating that most genital HPV genotypes represent separate serotypes, and the results suggest that the classification of serotypes is similar to that of genotypes. In addition, three cross-neutralizing MAbs were identified (HPV-16.J4, HPV-16.I23, and HPV-33.E12). MAb HPV-16.J4 recognized a conserved linear epitope located within the FG loop of the L1 protein, and HPV-16.I23 recognized another located within the DE loop. The results suggested that reactivity of MAb HPV-16.I23 to L1 protein is lost when leucine 152 of the HPV-16 L1 protein is replaced by phenylalanine. This confirmed the existence of linear epitopes within the L1 protein that induce neutralizing antibodies, and this is the first evidence that such linear epitopes induce cross-neutralization. However, the cross-neutralization induced by L1 VLPs represents less than 1% of the neutralizing activity induced by the dominant conformational epitopes, and it is questionable whether this is sufficient to offer cross-protection in vivo.

scholarly journals Short-term and long-term role of platelet activating factor as a mediator of in vivo platelet aggregation.

Circulation ◽  
1993 ◽  
Vol 88 (3) ◽  
pp. 1205-1214 ◽  
Author(s):  
P Golino ◽  
G Ambrosio ◽  
M Ragni ◽  
I Pascucci ◽  
M Triggiani ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activating Factor ◽  
Short Term

scholarly journals Novel Severe Hemophilia a Mouse Model with Factor VIII Intron 22 Inversion

Biology ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 704
Author(s):  
Jeong Pil Han ◽  
Dong Woo Song ◽  
Jeong Hyeon Lee ◽  
Geon Seong Lee ◽  
Su Cheong Yeom
Keyword(s):  
Mouse Model ◽  
Hemophilia A ◽  
Clinical Symptoms ◽  
Structural Similarity ◽  
Coagulation Disorder ◽  
Severe Hemophilia ◽  
Spontaneous Bleeding ◽  
Intron 22 Inversion ◽  
Fviii Activity

Hemophilia A (HA) is an X-linked recessive blood coagulation disorder, and approximately 50% of severe HA patients are caused by F8 intron 22 inversion (F8I22I). However, the F8I22I mouse model has not been developed despite being a necessary model to challenge pre-clinical study. A mouse model similar to human F8I22I was developed through consequent inversion by CRISPR/Cas9-based dual double-stranded breakage (DSB) formation, and clinical symptoms of severe hemophilia were confirmed. The F8I22I mouse showed inversion of a 391 kb segment and truncation of mRNA transcription at the F8 gene. Furthermore, the F8I22I mouse showed a deficiency of FVIII activity (10.9 vs. 0 ng/mL in WT and F8I22I, p < 0.0001) and severe coagulation disorder phenotype in the activated partial thromboplastin time (38 vs. 480 s, p < 0.0001), in vivo bleeding test (blood loss/body weight; 0.4 vs. 2.1%, p < 0.0001), and calibrated automated thrombogram assays (Thrombin generation peak, 183 vs. 21.5 nM, p = 0.0012). Moreover, histological changes related to spontaneous bleeding were observed in the liver, spleen, and lungs. We present a novel HA mouse model mimicking human F8I22I. With a structural similarity with human F8I22I, the F8I22I mouse model will be applicable to the evaluation of general hemophilia drugs and the development of gene-editing-based therapy research.

Mechanisms contributing to gastric motility changes induced by PAF-acether and endotoxin in rats

1989 ◽  
Vol 256 (2) ◽  
pp. G275-G282
Author(s):  
J. V. Esplugues ◽  
B. J. Whittle
Keyword(s):  
Gastric Motility ◽  
Platelet Activating Factor ◽  
Mucosal Damage ◽  
Serotonin Release ◽  
Initial Increase ◽  
Intragastric Pressure ◽  
Paf Receptor ◽  
Endogenous Release ◽  
Gastric Contractions

Platelet-activating factor (PAF) may be involved in the pathophysiology of gastrointestinal damage and motility changes. The effects of PAF in inducing gastric contractions in vivo have now been determined in pentobarbital sodium-anesthetized rats. Local intra-arterial infusion of PAF (5-50 ng.kg-1.min-1 for 10 min) induced a maintained rise in intragastric pressure followed by a further postinfusion increase. Inhibitors of eicosanoid biosynthesis had no effect on these gastric motility changes. However, pretreatment with cimetidine or methysergide decreased by 50% the initial increase in intragastric pressure, whereas mepyramine, adrenergic alpha- and beta-receptor blockade, atropine, hexamethonium, or vagotomy had no effect. During the local infusion of tetrodotoxin, the initial increase in intragastric pressure was not maintained, and the postinfusion increase was abolished. With these inhibitors and antagonists, there was no consistent correlation between the extent of PAF-induced mucosal damage and increase in intragastric pressure. Tetrodotoxin had no effect on the changes in intragastric pressure induced by the thromboxane mimetic U-46619. Administration of Escherichia coli and Salmonella typhosa endotoxin (50 mg/kg iv) also increased intragastric pressure, which peaked after 10 min and slowly declined thereafter. These effects were inhibited by the specific PAF-receptor antagonist L652,731, suggesting that the endogenous release of PAF may contribute to the endotoxin-induced increases in gastric motility. The present study suggests that PAF initially acts directly on smooth muscle and through histamine and serotonin release with a secondary motility response due to activation of nonadrenergic noncholinergic, neuronal activity.

Platelet-activating factor contributes to acute lung leak in rats given interleukin-1 intratracheally

2000 ◽  
Vol 279 (1) ◽  
pp. L75-L80 ◽  
Author(s):  
Young M. Lee ◽  
Brooks M. Hybertson ◽  
Hyun G. Cho ◽  
Lance S. Terada ◽  
Okyong Cho ◽  
...  
Keyword(s):  
Interleukin 1 ◽  
Platelet Activating Factor ◽  
Lavage Fluid ◽  
Lung Lavage ◽  
Myeloperoxidase Activity ◽  
Cerium Chloride ◽  
Neutrophil Accumulation ◽  
Web 2086

Lung lavage fluid of patients with acute lung injury (ALI) has increased levels of interleukin-1 (IL-1) and neutrophils, but their relationship to the lung leak that characterizes these patients is unclear. To address this concern, we investigated the role of the neutrophil agonist platelet-activating factor [1- O-alkyl-2-acetyl- sn-glycero-3-phosphocholine (PAF)] in the development of the acute neutrophil-dependent lung leak that is induced by giving IL-1 intratracheally to rats. We found that PAF acetyltransferase and PAF activities increased in lungs of rats given IL-1 intratracheally compared with lungs of sham-treated rats given saline intratracheally. The participation of PAF in the development of lung leak and lung neutrophil accumulation after IL-1 administration was suggested when treatment with WEB-2086, a commonly used PAF-receptor antagonist, decreased lung leak, lung myeloperoxidase activity, and lung lavage fluid neutrophil increases in rats given IL-1 intratracheally. Additionally, neutrophils recovered from the lung lavage fluid of rats given IL-1 intratracheally reduced more nitro blue tetrazolium (NBT) in vitro than neutrophils recovered from control rats or rats that had been given WEB-2086 and then IL-1. Histological examination indicated that the endothelial cell-neutrophil interfaces of cerium chloride-stained lung sections of rats given IL-1 contained increased cerium perhydroxide (the reaction product of cerium chloride with hydrogen peroxide) compared with lungs of control rats or rats treated with WEB-2086 and then given IL-1 intratracheally. These in vivo findings were supported by parallel findings showing that WEB-2086 treatment decreased neutrophil adhesion to IL-1-treated cultured endothelial cells in vitro. We concluded that PAF contributes to neutrophil recruitment and neutrophil activation in lungs of rats given IL-1 intratracheally.

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