RESUMO
Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder mediated by complexes between platelet factor 4 (PF4) and heparin or other polyanions, but the risk of thrombosis extends beyond exposure to heparin implicating other PF4 partners. We recently reported that peri-thrombus endothelium is targeted by HIT antibodies, but the binding site(s) has not been identified. We now show that PF4 binds at multiple discrete sites along the surface of extended strings of von Willebrand factor (VWF) released from the endothelium following photochemical injury in an endothelialized microfluidic system under flow. The HIT-like monoclonal antibody KKO and HIT patient antibodies recognize PF4-VWF complexes, promoting platelet adhesion and enlargement of thrombi within the microfluidic channels. Platelet adhesion to the PF4-VWF-HIT antibody complexes is inhibited by antibodies that block FcγRIIA or the glycoprotein Ib-IX complex on platelets. Disruption of PF4-VWF-HIT antibody complexes by drugs that prevent or block VWF oligomerization attenuate thrombus formation in a murine model of HIT. Together, these studies demonstrate assembly of HIT immune complexes along VWF strings released by injured endothelium that might propagate the risk of thrombosis in HIT. Disruption of PF4-VWF complex formation may provide a new therapeutic approach to HIT.
Assuntos
Anticorpos/imunologia , Anticoagulantes/efeitos adversos , Heparina/efeitos adversos , Fator Plaquetário 4/imunologia , Trombocitopenia/induzido quimicamente , Trombose/etiologia , Fator de von Willebrand/imunologia , Animais , Anticoagulantes/imunologia , Heparina/imunologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Adesividade Plaquetária , Trombocitopenia/complicações , Trombocitopenia/imunologia , Trombocitopenia/patologia , Trombose/imunologia , Trombose/patologiaRESUMO
INTRODUCCIÓN. Las alteraciones hereditarias de la hemostasia son patologías raras, dentro de estas se encuentran: Hemofilia A, Hemofilia B y von Willebrand. La hemofilia es un trastorno hereditario, ligado al cromosoma X, causado por ausencia o actividad reducida del factor VIII o IX. La enfermedad de von Willebrand es causada por la deficiencia del factor VIII. OBJETIVO. Determinar el perfil demográfico y epidemiológico de pacientes con Hemofilia y von Willebrand. MATERIALES Y MÉTODOS. Estudio observacional, descriptivo, transversal. La población de estudio fueron 133719 con una muestra de 144 pacientes, los criterios de inclusión fueron: pacientes de ambos sexos entre 2 a 88 años de edad, con diagnóstico de Hemofilia A, B, von Willebrand. Atendidos en la consulta externa del Área de Estomatología del Hospital de Especialidades Carlos Andrade Marín, en el periodo 2015-2018. Datos obtenidos del sistema AS400, analizados en el programa International Business Machines Statistical Package for the Social Sciences, Versión 22.0. RESULTADOS. El 77,0% (111; 144) perteneció al género masculino. El rango de edad fue entre 23 y 33 años con 24,0% (34; 144). Tuvieron Hemofilia A 62,0% (93; 144); Hemofilia B 6,0% (9; 144); von Willerbrand 28,0% (42; 144). El 50,0% (77; 144) recibieron tratamientos odontológicos; preventivos 15,0% (21; 144) y curativos 13,0% (18; 144); siendo la mayor patología caries dental. CONCLUSIÓN. Se determinó el perfil demográfico y epidemiológico de los pacientes con Hemofilia y von Willebrand que permitió brindar un tratamiento integral, interdisciplinario y oportuno.
INTRODUCTION. Hereditary abnormalities of hemostasis are rare pathologies, within these are: Hemophilia A, Hemophilia B and von Willebrand. Hemophilia is an inherited disorder, linked to the X chromosome, caused by absence or reduced activity of factor VIII or IX. Von Willebrand's disease is caused by factor VIII deficiency. OBJECTIVE. Determine the demographic and epidemiological profile of patients with hemophilia and von Willebrand. MATERIALS AND METHODS. Observational, descriptive, cross-sectional study. The study population was 133719 with a sample of 144 patients, the inclusion criteria were: patients of both sexes between 2 and 88 years of age, with a diagnosis of Hemophilia A, B, von Willebrand. Attended in the external consultation of the Stomatology Area of the Carlos Andrade Marín Specialty Hospital, in the period 2015-2018. Data obtained from the AS400 system, analyzed in the International Business Machines Statistical Package for the Social Sciences program, Version 22.0. RESULTS 77,0% (111; 144) belonged to the male gender. The age range was between 23 and 33 years with 24,0% (34; 144). They had hemophilia at 62,0% (93; 144); Hemophilia B 6,0% (9; 144); von Willerbrand 28,0% (42; 144). 50,0% (77; 144) received dental treatments; preventive 15,0% (21; 144) and curative 13,0% (18; 144); being the biggest dental caries pathology. CONCLUSION. The demographic and epidemiological profile of patients with Hemophilia and von Willebrand was determined, which allowed to provide a comprehensive, interdisciplinary and timely treatment.
Assuntos
Humanos , Masculino , Feminino , Doenças de von Willebrand , Odontologia Preventiva , Hemofilia B , Assistência Odontológica para Doentes Crônicos , Deficiência do Fator XI , Hemofilia A , Cromossomo X , Adesividade Plaquetária , HemostasiaRESUMO
Platelets are considered as significant players in innate and adaptive immune responses. The adhesion molecules they express, including P-selectin, CD40L, and CD42b, facilitate interactions with many cellular effectors. Upon interacting with a pathogen, platelets rapidly express and enhance their adhesion molecules, and secrete cytokines and chemokines. A similar phenomenon occurs after exposure of platelets to thrombin, an agonist extensively used for in vitro activation of these cells. It was recently reported that the dengue virus not only interacts with platelets but possibly infects them, which triggers an increased expression of adhesion molecule P-selectin as well as secretion of IL-1ß. In the present study, surface molecules of platelets like CD40L, CD42b, CD62P, and MHC class I were evaluated at 4 h of interaction with dengue virus serotype 2 (DENV-2), finding that DENV-2 induced a sharp rise in the membrane expression of all these molecules. At 2 and 4 h of DENV-2 stimulation of platelets, a significantly greater secretion of soluble CD40L (sCD40L) was found (versus basal levels) as well as cytokines such as GM-CSF, IL-6, IL-8, IL-10, and TNF-α. Compared to basal, DENV-2 elicited more than two-fold increase in these cytokines. Compared to the thrombin-induced response, the level generated by DENV-2 was much higher for GM-CSF, IL-6, and TNF-α. All these events induced by DENV end up in conspicuous morphological changes observed in platelets by confocal microscopy and transmission electron microscopy, very different from those elicited by thrombin in a more physiological scenery.
Assuntos
Plaquetas/metabolismo , Ligante de CD40/metabolismo , Membrana Celular/metabolismo , Vírus da Dengue/fisiologia , Dengue/sangue , Dengue/virologia , Complexo Glicoproteico GPIb-IX de Plaquetas/metabolismo , Plaquetas/imunologia , Ligante de CD40/sangue , Estudos de Casos e Controles , Moléculas de Adesão Celular/metabolismo , Citocinas/metabolismo , Citosol/metabolismo , Dengue/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Selectina-P/metabolismo , Adesividade Plaquetária , Agregação PlaquetáriaRESUMO
La refractariedad plaquetaria representa un problema clínico significativo que complica la transfusión de plaquetas, está asociada con resultados clínicos adversos y elevados costos hospitalarios. Se define como una respuesta inadecuada a la transfusión de plaquetas después de dos transfusiones consecutivas. Las causas no inmunes son las más frecuentes y las primeras que deben ser investigadas en el diagnóstico de refractariedad plaquetaria. La refractariedad de causa inmune está mediada por anticuerpos contra antígenos HLA o HPA. Si se identifican los anticuerpos, existen tres formas de identificar unidades de plaquetas compatibles: el tipaje HLA, la prueba cruzada y la predicción de la especificidad del anticuerpo. Se recomienda el empleo de plaquetas fresca ABO idénticas y fenotipadas para eliminar estas variables potenciales como causa de refractariedad(AU)
Platelet refractoriness represent a significant clinical problem that complicates the provision of platelet transfusions, it is associated with adverse clinical outcomes and increases health care costs. Platelet refractoriness is defined as an inadequate response to platelet transfusions after two sequential transfusions. Nonimmune causes are the most likely and the first that should be explored in the diagnosis of platelet refractoriness. Immune-mediated platelet refractoriness is cause by antibodies to human leukocyte antigens (HLAs) and/or human platelet antigens. If antibodies are identified, there are 3 strategies for identifying compatible platelet units: HLA matching, crossmatching, and antibody specificity prediction. It is recommended to use fresh and ABO-matched platelets in the diagnosis of platelet refractoriness to eliminate these potential variables as causes of refractoriness(AU)
Assuntos
Humanos , Masculino , Feminino , Adesividade Plaquetária , Transfusão de Plaquetas/métodos , Resultado do TratamentoRESUMO
Platelets are anucleated blood cells derived from megakaryocytes, and although they are essential for proper hemostasis, their function extends to physiologic processes such as tissue repair, wound remodeling, and antimicrobial host defense, or pathologic conditions such as thrombosis, atherosclerosis, chronic inflammatory diseases, and cancer. Recently, we demonstrated that two structurally divergent members of the galectin family, galectin-1 and galectin-8, are potent platelet agonists. The emergence of galectins as soluble mediators capable of triggering platelet activation opens a new field of research that will provide further insights into the mechanisms linking inflammatory responses to thrombus formation and could expand our view of the role of platelets much beyond hemostasis to their pathophysiologic role during inflammation and cancer. The present article details the various protocols and reagents currently used in our laboratory to study the role of galectins in human platelet function.
Assuntos
Plaquetas/fisiologia , Galectinas/metabolismo , Plaquetas/citologia , Plaquetas/metabolismo , Separação Celular , Galectinas/química , Humanos , Proteínas Imobilizadas/química , Proteínas Imobilizadas/metabolismo , Leucócitos Mononucleares/citologia , Adesividade Plaquetária , Agregação Plaquetária , Contagem de Plaquetas , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Transdução de Sinais , Tromboxano A2/metabolismoRESUMO
El síndrome de las plaquetas pegajosas es un trastorno plaquetario autosómico dominante considerado como una de las causas más frecuentes de eventos trombóticos. Se cree que el defecto específico puede estar localizado en los receptores de la superficie plaquetaria y está caracterizado por un incremento anormal en la agregabilidad de las plaquetas con difosfato de adenosina, epinefrina, o ambos. En estudios realizados acerca de esta entidad se ha descrito una elevada incidencia, pero esta se ha calculado en pacientes que han tenido episodios trombóticos previos (enfermedad tromboembólica, infarto agudo del miocardio y accidente cerebrovascular), antecedentes familiares o tienen factores de riesgo para este tipo de eventos, mientras que su incidencia en una población de mujeres en edad fértil, con dos o más pérdidas de embarazo y sin antecedentes es desconocida. En el presente trabajo se estudiaron un total de 126 pacientes femeninas con al menos dos pérdidas de embarazo; de ellas, 27 resultaron positivas al estudio de hipersensibilidad plaquetaria con difosfato de adenosina y epinefrina mediante pruebas de agregometría, lo que representa el 21 por ciento de positividad en la población estudiada. Es significativo que la clase de síndrome de plaqueta pegajosa predominante fue de tipo II (hipersensibilidad con epinefrina). Finalmente, destacar que el seguimiento y tratamiento oportuno durante la gestación en las pacientes incluidas en el estudio ha permitido el nacimiento de 4 niños saludables de madres con síndrome de plaquetas pegajosas...
The sticky platelet syndrome is an autosomal dominant platelet disorder considered one of the most frequent causes of thrombotic events. It is supposed that the specific fault can be localized to the platelet surface receptor and is characterized by an abnormal increase in aggregability adenosine diphosphate and/or epinephrine. In studies on this entity a high incidence has been described, but this was calculated in patients who have had previous thrombotic events (thromboembolic disease, myocardial infarction and stroke), family history or risk factors for this kind of events, while its incidence in a population of women of childbearing age with two or more pregnancy losses and no previous history is unknown.During our research a total of 126 female patients with at least two miscarriages were studied; 27 of them showed platelet hypersensitivity to adenosine diphosphate and epinephrine by testing aggregometry, which represents 21 percent positivity in the population studied. It is significant that the sticky platelet syndrome was predominantly of type II (hypersensitivity with epinephrine). In conclusion, we consider important to remark that with the monitoring and opportune treatment during pregnancy, four of the patients included in our study gave birth four healthy children despite the sticky platelet syndrome...
Assuntos
Humanos , Feminino , Gravidez , Adesividade Plaquetária/imunologia , Complicações na Gravidez/diagnóstico , Complicações na Gravidez/epidemiologia , Morte Fetal/prevenção & controleRESUMO
BACKGROUND: The inhibitory effect of adenosine on platelet aggregation is abrogated after the addition of adenosine-deaminase. Inosine is a naturally occurring nucleoside degraded from adenosine. OBJECTIVES: The mechanisms of antiplatelet action of adenosine and inosine in vitro and in vivo, and their differential biological effects by molecular modeling were investigated. RESULTS: Adenosine (0.5, 1 and 2 mmol/L) inhibited phosphatidylserine exposure from 52±4% in the control group to 44±4 (p<0.05), 29±2 (p<0.01) and 20±3% (p<0.001). P-selectin expression in the presence of adenosine 0.5, 1 and 2 mmol/L was inhibited from 32±4 to 27±2 (p<0.05), 14±3 (p<0.01) and 9±3% (p<0.001), respectively. At the concentrations tested, only inosine to 4 mmol/L had effect on platelet P-selectin expression (p<0.05). Adenosine and inosine inhibited platelet aggregation and ATP release stimulated by ADP and collagen. Adenosine and inosine reduced collagen-induced platelet adhesion and aggregate formation under flow. At the same concentrations adenosine inhibited platelet aggregation, decreased the levels of sCD40L and increased intraplatelet cAMP. In addition, SQ22536 (an adenylate cyclase inhibitor) and ZM241385 (a potent adenosine receptor A2A antagonist) attenuated the effect of adenosine on platelet aggregation induced by ADP and intraplatelet level of cAMP. Adenosine and inosine significantly inhibited thrombosis formation in vivo (62±2% occlusion at 60 min [nâ=â6, p<0.01] and 72±1.9% occlusion at 60 min, [nâ=â6, p<0.05], respectively) compared with the control (98±2% occlusion at 60 min, nâ=â6). A2A is the adenosine receptor present in platelets; it is known that inosine is not an A2A ligand. Docking of adenosine and inosine inside A2A showed that the main difference is the formation by adenosine of an additional hydrogen bond between the NH2 of the adenine group and the residues Asn253 in H6 and Glu169 in EL2 of the A2A receptor. CONCLUSION: Therefore, adenosine and inosine may represent novel agents lowering the risk of arterial thrombosis.
Assuntos
Adenosina/farmacologia , Coagulação Sanguínea/efeitos dos fármacos , Plaquetas/metabolismo , Inosina/farmacologia , Modelos Biológicos , Adesividade Plaquetária/efeitos dos fármacos , Animais , Colágeno/metabolismo , Humanos , Masculino , Camundongos , Trombose/tratamento farmacológico , Trombose/metabolismoRESUMO
Waste bagasse of Agave tequilana-Weber fibers treated with sodium hydroxide was used to elaborate hydrogel films. The bagasse was offered in an alternative use for the preparation of hydrogel films by phase inversion method without crosslinking and further purification of cellulose. The effect on the properties of the obtained films was studied when the chemical treatment of the agave fibers was changed. It was found that the resultant hydrogels showed increment in tensile from 40 N/mm(2) to 56 N/mm(2) with the increase of sodium hypochlorite concentration from 1 to 10 vol.%, respectively. With regard to biocompatibility properties of the hydrogel films, platelet adhesion, clotting time and protein adsorption were investigated. Analysis of the morphology of adherent NIH3T3 fibroblast indicated that the projected cell area, aspect ratio and long axis gradually increased with the increment of sodium hypochlorite content in the agave treatment. It was presented that the chemical treatment affects cell adhesion and morphology and lignin content remains in the brown fibers.
Assuntos
Agave/química , Materiais Biocompatíveis/química , Celulose/química , Metilgalactosídeos/química , Hipoclorito de Sódio/química , Animais , Materiais Biocompatíveis/toxicidade , Plaquetas/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Metilgalactosídeos/toxicidade , Camundongos , Células NIH 3T3 , Adesividade PlaquetáriaRESUMO
BACKGROUND: Chlorogenic acid is a potent phenolic antioxidant. However, its effect on platelet aggregation, a critical factor in arterial thrombosis, remains unclear. Consequently, chlorogenic acid-action mechanisms in preventing platelet activation and thrombus formation were examined. METHODS AND RESULTS: Chlorogenic acid in a dose-dependent manner (0.1 to 1 mmol/L) inhibited platelet secretion and aggregation induced by ADP, collagen, arachidonic acid and TRAP-6, and diminished platelet firm adhesion/aggregation and platelet-leukocyte interactions under flow conditions. At these concentrations chlorogenic acid significantly decreased platelet inflammatory mediators (sP-selectin, sCD40L, CCL5 and IL-1ß) and increased intraplatelet cAMP levels/PKA activation. Interestingly, SQ22536 (an adenylate cyclase inhibitor) and ZM241385 (a potent A2A receptor antagonist) attenuated the antiplatelet effect of chlorogenic acid. Chlorogenic acid is compatible to the active site of the adenosine A2A receptor as revealed through molecular modeling. In addition, chlorogenic acid had a significantly lower effect on mouse bleeding time when compared to the same dose of aspirin. CONCLUSIONS: Antiplatelet and antithrombotic effects of chlorogenic acid are associated with the A2A receptor/adenylate cyclase/cAMP/PKA signaling pathway.
Assuntos
Ácido Clorogênico/farmacologia , Ativação Plaquetária/efeitos dos fármacos , Trombose/prevenção & controle , Adenina/análogos & derivados , Adenina/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Sítios de Ligação , Tempo de Sangramento , Comunicação Celular/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Colágeno/farmacologia , AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Ativação Enzimática/efeitos dos fármacos , Hemorreologia/efeitos dos fármacos , Humanos , Mediadores da Inflamação/metabolismo , Leucócitos/citologia , Leucócitos/efeitos dos fármacos , Camundongos , Modelos Moleculares , Selectina-P/metabolismo , Adesividade Plaquetária/efeitos dos fármacos , Agregação Plaquetária/efeitos dos fármacos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Receptor A2A de Adenosina/metabolismo , Trombose/metabolismo , Trombose/patologia , Triazinas/farmacologia , Triazóis/farmacologiaRESUMO
OBJECTIVES: Intravascular hemolysis may have important pathophysiological consequences, such as the induction of cellular adhesion and vasculopathy. We compared the adhesive properties of red cells (RBC) and platelets in hereditary spherocytosis (HS), paroxysmal nocturnal hemoglobinuria (PNH) and sickle cell disease (SCD) patients. DESIGN AND METHODS: The adhesion of RBC and platelets, from patients and healthy subjects, was determined using static adhesion assays. RBC surface markers were characterized by flow cytometry and lactate dehydrogenase (LDH), plasma hemoglobin (pHb) and TNF-α were assayed in serum/plasma samples. RESULTS: pHb levels were elevated in all three hemolytic diseases, indicating the incidence of intravascular hemolysis. RBC adhesion and TNF-α were augmented in HS and SCD, but not in PNH. Reticulocyte counts were raised in the three diseases, but were higher in HS and SCD than in PNH; high expressions of CD71, CD36 and CD49d were observed on SCD RBC, while CD71 alone was increased on HS and PNH RBC. Splenectomy was associated with reversals of increased pHb, RBC adhesion, reticulocytes, RBC marker expression and inflammation in HS. In contrast, platelet adhesion was elevated in SCD and PNH, but not HS. Platelet adhesion correlated significantly with serum LDH, but not pHb, in the hemolytic disease cohort; interestingly, LDH did not correlate with reticulocytes or pHb levels. CONCLUSIONS: Results indicate that extravascular, rather than intravascular, hemolysis (and ensuing RBC production) may contribute to elevations in RBC adhesive properties in HS and SCD, while mechanisms peculiar to each disease may augment platelet adhesion in SCD and PNH.