RESUMO
Introduction: Platelets have essential functions as first responders in the immune response to pathogens. Activation and aggregation of platelets in bacterial infections can lead to life-threatening conditions such as arterial thromboembolism or sepsis-associated coagulopathy. Methods: In this study, we investigated the role of complement in Escherichia coli (E. coli)-induced platelet aggregation in human whole blood, using Multiplate® aggregometry, flow cytometry, and confocal microscopy. Results and Discussion: We found that compstatin, which inhibits the cleavage of complement component C3 to its components C3a and C3b, reduced the E. coli-induced platelet aggregation by 42%-76% (p = 0.0417). This C3-dependent aggregation was not C3a-mediated as neither inhibition of C3a using a blocking antibody or a C3a receptor antagonist, nor the addition of purified C3a had any effects. In contrast, a C3b-blocking antibody significantly reduced the E. coli-induced platelet aggregation by 67% (p = 0.0133). We could not detect opsonized C3b on platelets, indicating that the effect of C3 was not dependent on C3b-fragment deposition on platelets. Indeed, inhibition of glycoprotein IIb/IIIa (GPIIb/IIIa) and complement receptor 1 (CR1) showed that these receptors were involved in platelet aggregation. Furthermore, aggregation was more pronounced in hirudin whole blood than in hirudin platelet-rich plasma, indicating that E. coli-induced platelet aggregation involved other blood cells. In conclusion, the E. coli-induced platelet aggregation in human whole blood is partly C3b-dependent, and GPIIb/IIIa and CR1 are also involved in this process.
Assuntos
Plaquetas , Complemento C3b , Escherichia coli , Agregação Plaquetária , Humanos , Plaquetas/efeitos dos fármacos , Plaquetas/imunologia , Complemento C3b/imunologia , Hirudinas/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Agregação Plaquetária/imunologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Técnicas In VitroRESUMO
Candida albicans is the most common fungal pathogen in humans, causing invasive disease and even potentially life-threatening systemic infections when tissue homeostasis is disrupted. Previous studies have identified an essential role of platelets in infection and immunity, especially when they are activated. However, it is still unclear whether platelets can be activated by C. albicans, and even less is known about the role of platelets in C. albicans infection. Herein, we showed that C. albicans induced platelet activation in vitro. C. albicans elevated the levels of AKT Ser473 phosphorylation, and inhibition of the PI3K-AKT signaling pathway reversed C. albicans-induced platelet activation. Surprisingly, C. albicans-induced platelet activation occurred in an integrin glycoprotein (GP) IIb/IIIa-dependent manner but was independent of the pattern recognition receptors toll-like receptor (TLR) 2 and TLR4. Interestingly, platelets enhanced the phagocytosis of human monocytes challenged with C. albicans and upregulated the expression of inflammatory cytokines, which were dependent on platelet activation mediated by GP IIb/IIIa. The present work provides new insights into the role of activated platelets in the defense against C. albicans, highlighting the importance of GP IIb/IIIa in the recognition of C. albicans.
Assuntos
Candida albicans , Monócitos/imunologia , Ativação Plaquetária , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Plaquetas/imunologia , Células Cultivadas , Humanos , Fosfatidilinositol 3-Quinases , Proteínas Proto-Oncogênicas c-aktRESUMO
Misclassification of immune thrombocytopenia (ITP) is common, which might undermine the value of platelet autoantibody testing. We determined the sensitivity and specificity of platelet autoantibody testing using the direct antigen capture assay for anti-glycoprotein (GP) IIb/IIIa or anti-GPIbIX in patients with 'definite ITP', defined as those with a documented treatment response. Sensitivity of platelet autoantiboody testing increased from 48·3% [95% confidence interval (CI) 43·5-53·2] for all ITP patients to 64·7% (95% CI 54·6-73·9) for definite ITP patients. Specificity was unchanged [75·3% (95% CI 67·5-82·1)]. High optical density values (>0·8) improved the specificity of platelet autoantibody testing but lowered sensitivity. In patients with a high pretest probability, platelet autoantibodies can aid in the diagnosis of ITP and may be most prevalent in certain patient subsets.
Assuntos
Autoanticorpos/imunologia , Plaquetas/imunologia , Púrpura Trombocitopênica Idiopática/imunologia , Adulto , Idoso , Feminino , Humanos , Imunoensaio , Masculino , Pessoa de Meia-Idade , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Complexo Glicoproteico GPIb-IX de Plaquetas/imunologia , Púrpura Trombocitopênica Idiopática/diagnósticoRESUMO
This retrospective study aimed to evaluate the relationship between plasma autoantibody species and rhTPO response in adult ITP patients who failed the first-line treatments. Plasma anti-glycoprotein (GP) IIb/IIIa and anti-GPIb/IX autoantibodies were detected in 47·2% and 40·6% of the 123 patients, respectively. Overall response rate to rhTPO treatment in patients without anti-GPIb/IX autoantibodies was significantly higher than patients with anti-GPIb/IX autoantibodies (82·2% vs. 60·0%, P = 0·006). By contrast, no statistical difference in response rate was observed between patients with or without anti-GPIIb/IIIa autoantibodies (74·1% vs. 72·3%, P = 0·819). Therefore, the presence of anti-GPIb/IX autoantibodies might serve as a predictive factor for poor response to rhTPO treatment in ITP.
Assuntos
Autoanticorpos/imunologia , Autoantígenos/imunologia , Plaquetas/imunologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Complexo Glicoproteico GPIb-IX de Plaquetas/imunologia , Púrpura Trombocitopênica Idiopática/imunologia , Trombopoetina/uso terapêutico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Especificidade de Anticorpos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Púrpura Trombocitopênica Idiopática/tratamento farmacológico , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/uso terapêutico , Estudos Retrospectivos , Trombopoetina/imunologia , Adulto JovemRESUMO
BACKGROUND: To make an accurate estimate of the response to thrombopoietin (TPO) receptor agonists for thrombocytopenia associated with chronic liver disease, we evaluated the influence of antiplatelet autoantibodies on the response to lusutrombopag in thrombocytopenic patients with liver disease. METHODS: A prospective study was conducted at 2 hospitals. Thrombocytopenic patients with liver disease received oral lusutrombopag 3.0 mg once daily for up to 7 days. We analyzed changes in platelet counts from baseline to the maximum platelet count on days 9-14. The definition of clinical response was a platelet count of ≥5 × 104/µL with an increased platelet count of ≥2 × 104/µL from baseline. We assessed the correlation between the response to treatment drug and antiplatelet autoantibodies measured by anti-GPIIb/IIIa antibody-producing B cells. RESULTS: Thirty patients received the trial drug. There were 25 responders and 5 nonresponders. The median change in platelet counts was 3.9 × 104/µL (95% CI 2.8-4.6, p < 0.0001). The correlation between change in platelet counts and the frequency of the anti-glycoprotein IIb/IIIa antibody-producing B cells was moderate (r = 0.414, 95% CI 0.064-0.674, p = 0.023). In multivariate analysis of factors affecting the change in platelet counts, the anti-GPIIb/IIIa antibody-producing B cells were identified as an independent factor (regression coefficient [B] = 0.089; CI 0.021-0.157, p = 0.013). CONCLUSION: Anti-GPIIb/IIIa antibody-producing B cells may be a predictor for TPO receptor agonists in patients with chronic liver disease.
Assuntos
Autoanticorpos/biossíntese , Linfócitos B/imunologia , Cinamatos/uso terapêutico , Hepatopatias/complicações , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Tiazóis/uso terapêutico , Trombocitopenia/tratamento farmacológico , Trombocitopenia/imunologia , Idoso , Idoso de 80 Anos ou mais , Autoanticorpos/imunologia , Plaquetas/patologia , Cinamatos/administração & dosagem , Feminino , Humanos , Hepatopatias/sangue , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Tamanho do Órgão , Contagem de Plaquetas , Estudos Prospectivos , Baço/patologia , Tiazóis/administração & dosagem , Trombocitopenia/sangue , Trombocitopenia/complicaçõesRESUMO
The commensal microbiota is a recognized enhancer of arterial thrombus growth. While several studies have demonstrated the prothrombotic role of the gut microbiota, the molecular mechanisms promoting arterial thrombus growth are still under debate. Here, we demonstrate that germ-free (GF) mice, which from birth lack colonization with a gut microbiota, show diminished static deposition of washed platelets to type I collagen compared with their conventionally raised (CONV-R) counterparts. Flow cytometry experiments revealed that platelets from GF mice show diminished activation of the integrin αIIbß3 (glycoprotein IIbIIIa) when activated by the platelet agonist adenosine diphosphate (ADP). Furthermore, washed platelets from Toll-like receptor-2 (Tlr2)-deficient mice likewise showed impaired static deposition to the subendothelial matrix component type I collagen compared with wild-type (WT) controls, a process that was unaffected by GPIbα-blockade but influenced by von Willebrand factor (VWF) plasma levels. Collectively, our results indicate that microbiota-triggered steady-state activation of innate immune pathways via TLR2 enhances platelet deposition to subendothelial matrix molecules. Our results link host colonization status with the ADP-triggered activation of integrin αIIbß3, a pathway promoting platelet deposition to the growing thrombus.
Assuntos
Difosfato de Adenosina/farmacologia , Plaquetas/efeitos dos fármacos , Colágeno Tipo I/genética , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Trombose/microbiologia , Fator de von Willebrand/genética , Animais , Artérias/metabolismo , Artérias/patologia , Plaquetas/imunologia , Plaquetas/patologia , Adesão Celular/efeitos dos fármacos , Colágeno Tipo I/imunologia , Feminino , Microbioma Gastrointestinal/imunologia , Expressão Gênica , Vida Livre de Germes , Humanos , Imunidade Inata , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/agonistas , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Complexo Glicoproteico GPIb-IX de Plaquetas/genética , Complexo Glicoproteico GPIb-IX de Plaquetas/imunologia , Cultura Primária de Células , Simbiose/imunologia , Trombose/genética , Trombose/imunologia , Trombose/patologia , Receptor 2 Toll-Like/deficiência , Receptor 2 Toll-Like/genética , Receptor 2 Toll-Like/imunologia , Fator de von Willebrand/imunologiaAssuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Autoanticorpos/sangue , Neoplasias Colorretais/tratamento farmacológico , Monócitos , Trombocitopenia/imunologia , Idoso , Autoanticorpos/imunologia , Humanos , Contagem de Leucócitos , Masculino , Metilprednisolona/efeitos adversos , Oxaliplatina/efeitos adversos , Contagem de Plaquetas , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Trombocitopenia/sangue , Trombocitopenia/induzido quimicamente , Trombocitopenia/diagnósticoAssuntos
Antígenos de Plaquetas Humanas/imunologia , Autoanticorpos/imunologia , Eptifibatida/efeitos adversos , Inibidores da Agregação Plaquetária/efeitos adversos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Púrpura Trombocitopênica Idiopática/etiologia , Infarto do Miocárdio com Supradesnível do Segmento ST/sangue , Trombose/etiologia , Arginina/análogos & derivados , Arginina/uso terapêutico , Aspirina/uso terapêutico , Terapia Combinada , Trombose Coronária/etiologia , Trombose Coronária/cirurgia , Substituição de Medicamentos , Quimioterapia Combinada , Eptifibatida/imunologia , Eptifibatida/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Intervenção Coronária Percutânea , Ácidos Pipecólicos/uso terapêutico , Inibidores da Agregação Plaquetária/imunologia , Inibidores da Agregação Plaquetária/uso terapêutico , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Transfusão de Plaquetas , Púrpura Trombocitopênica Idiopática/imunologia , Púrpura Trombocitopênica Idiopática/terapia , Infarto do Miocárdio com Supradesnível do Segmento ST/tratamento farmacológico , Infarto do Miocárdio com Supradesnível do Segmento ST/terapia , Choque Cardiogênico/etiologia , Stents/efeitos adversos , Sulfonamidas/uso terapêutico , Trombectomia , Terapia Trombolítica , Trombose/tratamento farmacológico , Ticagrelor/uso terapêutico , Varfarina/uso terapêuticoRESUMO
BACKGROUND: In adult immune thrombocytopenia (ITP), an acquired autoimmune bleeding disorder, anti-platelet autoantibody testing may be useful as a rule-in test. Childhood ITP has different disease characteristics, and the diagnostic and prognostic value of anti-platelet antibody testing remains uncertain. OBJECTIVE: To systematically review the diagnostic accuracy of anti-platelet autoantibody testing in childhood ITP. METHODS: PubMed and EMBASE were searched for studies evaluating immunoassays in childhood ITP. Study quality was assessed (QUADAS2), and evidence was synthesized descriptively. RESULTS: In total, 40 studies (1606 patients) were identified. Nine studies reported sufficient data to determine diagnostic accuracy measures. Anti-platelet IgG antibody testing showed a moderate sensitivity (0·36-0·80 platelet-associated IgG [direct test]; 0·19-0·39 circulating IgG [indirect test]). In studies that reported control data, including patients with non-immune thrombocytopenia, specificity was very good (0·80-1·00). Glycoprotein-specific immunoassays showed comparable sensitivity (three studies) and predominantly identified IgG anti-GP IIb/IIIa antibodies, with few IgG anti-GP Ib/IX antibodies. Anti-platelet IgM antibodies were identified in a substantial proportion of children (sensitivity 0·62-0·64 for direct and indirect tests). CONCLUSION: The diagnostic evaluation of IgG and IgM anti-platelet antibodies may be useful as a rule-in test for ITP. In children with insufficient platelets for a direct test, indirect tests may be performed instead. A negative test does not rule out the diagnosis of ITP. Future studies should evaluate the value of anti-platelet antibody tests in thrombocytopenic children with suspected ITP.
Assuntos
Imunoensaio/métodos , Púrpura Trombocitopênica Idiopática/sangue , Testes Sorológicos/métodos , Autoanticorpos/imunologia , Criança , Humanos , Imunoensaio/normas , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Complexo Glicoproteico GPIb-IX de Plaquetas/imunologia , Púrpura Trombocitopênica Idiopática/diagnóstico , Púrpura Trombocitopênica Idiopática/imunologia , Sensibilidade e Especificidade , Testes Sorológicos/normasAssuntos
Agregação Plaquetária/fisiologia , Testes de Função Plaquetária/métodos , Trombastenia/sangue , Autoanticorpos/sangue , Perda Sanguínea Cirúrgica/fisiopatologia , Plaquetas , Feminino , Hemorragia/diagnóstico , Hemorragia/etiologia , Humanos , Pessoa de Meia-Idade , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Ristocetina/efeitos adversos , Trombastenia/metabolismo , Trombastenia/patologiaAssuntos
Plaquetas/imunologia , Plaquetas/metabolismo , Imunoglobulina G/imunologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Asma/complicações , Plaquetas/patologia , Pré-Escolar , Humanos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Infecções Respiratórias/sangue , Infecções Respiratórias/complicações , Infecções Respiratórias/diagnóstico , Infecções Respiratórias/etiologiaAssuntos
Metilprednisolona/efeitos adversos , Púrpura Trombocitopênica Idiopática/induzido quimicamente , Idoso , Anticorpos/sangue , Anticorpos/imunologia , Feminino , Humanos , Masculino , Metilprednisolona/imunologia , Pessoa de Meia-Idade , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologiaRESUMO
BACKGROUND: Cardiovascular disease has one of the highest mortality rates among all the diseases. Platelets play an important role in the pathogenesis of cardiovascular diseases. Platelet membrane glycoprotein GPIIb/IIIa antagonists are the most effective antiplatelet drugs, and pulaimab is one of these. The study aims to promote individual medication of pulaimab [anti-GPIIb/IIIa F(ab)2 injection] by discovering the pharmacological relationship among the dose, concentration, and effects. The goal of this study is to establish a population pharmacokineticpharmacodynamic model to evaluate the antiplatelet effect of intravenous pulaimab injection. METHODS: Data were collected from 59 healthy subjects who participated in a Phase-I clinical trial. Plasma concentration was used as the pharmacokinetic index, and platelet aggregation inhibition rate was used as the pharmacodynamic index. The basic pharmacokinetics model was a two-compartment model, whereas the basic pharmacodynamics model was a sigmoid-EMAX model with a direct effect. The covariable model was established by a stepwise method. The final model was verified by a goodness-of-fit method, and predictive performance was assessed by a Bootstrap (BS) method. RESULTS: In the final model, typical population values of the parameters were as follows: central distribution Volume (V1), 183 L; peripheral distribution Volume (V2), 349 L; Central Clearance (CL), 31 L/h; peripheral clearance(Q), 204 L/h; effect compartment concentration reaching half of the maximum effect (EC50), 0.252 mg/L; maximum effect value (EMAX), 54.0%; and shape factor (γ), 0.42. In the covariable model, thrombin time had significant effects on CL and EMAX. Verification by the goodness-of-fit and BS methods showed that the final model was stable and reliable. CONCLUSION: A model was successfully established to evaluate the antiplatelet effect of intravenous pulaimab injection that could provide support for the clinical therapeutic regimen.
Assuntos
Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais/farmacocinética , Modelos Biológicos , Inibidores da Agregação Plaquetária/farmacologia , Inibidores da Agregação Plaquetária/farmacocinética , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Adulto , Feminino , Humanos , Masculino , Agregação Plaquetária/efeitos dos fármacos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologiaRESUMO
BACKGROUND: Fetal/neonatal alloimmune thrombocytopenia (FNAIT) results from maternal alloantibodies (abs) reacting with fetal platelets expressing paternal human platelet antigens (HPAs), mostly HPA-1a. Anti-HPA-1a abs, are the most frequent cause of severe thrombocytopenia and intracranial hemorrhage (ICH). OBJECTIVES: Titration of anti-HPA-1a in maternal serum using standard National Institute for Biological Standards and Control (NIBSC) 03/152 is one diagnostic approach to predict the severity of FNAIT. Recently, we found three anti-HPA-1a subtypes reacting with the ß3 subunit independently or dependently from complexes with αIIb and αv. Endothelial cell-reactive anti-αvß3 abs were found predominantly in cases with ICH. Our aim was to assess whether available standard material represents all anti-HPA-1a subtypes. MATERIALS AND METHODS: In this study, anti-HPA-1a sera (NIBSC 03/152) and human monoclonal antibodies (moabs) against HPA-1a (moabs 26.4 and 813) were evaluated using transfected cell lines expressing αIIbß3, αvß3 or monomeric cß3. RESULTS: Flow cytometry analyses with well-characterized murine moabs recognizing αIIbß3, αvß3, or ß3 alone demonstrated that AP3 reacts compound-independently, whereas compound-dependent moabs Gi5 and 23C6 reacted only with complexes. NIBSC 03/152, moabs 26.4, and 813 against HPA-1a reacted like AP3, same results were obtained with monomeric cß3 in immunoblotting. Antigen capture assay targeting endothelial cells showed anti-HPA-1a reactivity disappearance after cß3 beads adsorption. Furthermore, in contrast to anti-HPA-1a abs from ICH cases, none of NIBSC 03/152, 26.4, and 813 inhibited tube formation. CONCLUSION: These results suggest that current anti-HPA-1a standard material contains only the anti-ß3 subtype. The absence of anti-αvß3 makes NIBSC 03/152 less suitable as standard to predict the severity of FNAIT.
Assuntos
Anticorpos Monoclonais/imunologia , Especificidade de Anticorpos , Antígenos de Plaquetas Humanas/imunologia , Testes Imunológicos , Integrina alfaVbeta3/imunologia , Integrina beta3/imunologia , Isoanticorpos/imunologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Trombocitopenia Neonatal Aloimune/diagnóstico , Células Endoteliais/imunologia , Células HEK293 , Humanos , Isoanticorpos/sangue , Neovascularização Fisiológica , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Índice de Gravidade de Doença , Trombocitopenia Neonatal Aloimune/sangue , Trombocitopenia Neonatal Aloimune/imunologiaRESUMO
Due to the wealth of actors involved in the development of atherosclerosis, molecular imaging based on the targeting of specific markers would substantiate the diagnosis of life-threatening atheroma plaques. To this end, TEG4 antibody is a promising candidate targeting the activated platelets (integrin αIIbß3) highly represented within the plaque. In this study, scFv antibody fragments were used to functionalize multimodal imaging nanoparticles. This grafting was performed in a regio-selective way to preserve TEG4 activity and the avidity of the nanoparticles was studied with respect to the number of grafted antibodies. Subsequently, taking advantage of the nanoparticle bimodality, both near infrared fluorescence and magnetic resonance imaging of the atheroma plaque were performed in the ApoE-/- mouse model. Here we describe the design of the targeted nanoparticles, and a quantification method for their detection in mice, both ex vivo and in vivo, highlighting their value as a potential diagnosis agent.
Assuntos
Aterosclerose/diagnóstico , Imagem Molecular , Imagem Multimodal , Nanopartículas/química , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Anticorpos de Cadeia Única/imunologia , Animais , Aterosclerose/patologia , Fluorescência , Imageamento por Ressonância Magnética , Masculino , Camundongos , Coelhos , Distribuição TecidualRESUMO
Thrombocytopaenia can be associated with an autoimmune mechanism. Immune thrombocytopaenia can be associated with thyroid autoimmune disease. The authors present a case of a teenager with a history of thrombocytopaenia who complained of tiredness. Laboratory investigation showed thyroid autoantibodies. The co-existence of thrombocytopaenia and thyroiditis lead to further investigation and antibodies against platelet glycoprotein IIbIIIa were found. This case illustrates the association of the overlap aspects between thyroid and platelet autoimmunity.
Assuntos
Autoanticorpos/imunologia , Trombocitopenia/imunologia , Tireoidite Autoimune/imunologia , Adolescente , Autoanticorpos/sangue , Feminino , Humanos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Trombocitopenia/sangue , Tireoidite Autoimune/sangueRESUMO
The association of immune thrombocytopenia (ITP) with cancer has been reported, but the causality of tumor cells in paraneoplastic ITP pathogenesis and maintenance has never been established. We analyzed the unusual case of refractory ITP and coincident urothelial tumor of the kidney with circulating high titer anti-GPIIBIIIA autoantibodies. Intriguingly, after nephrectomy, the patient recovered fully and her anti-GPIIBIIIA autoantibodies disappeared. Proteomic and immunohistochemistry analyses revealed erratic GPIIB expression by the tumor cells, suggesting possible antigenic mimicry chronically stimulating the immune system and leading to this patient's refractory ITP. Such previously unreported findings provide proof-of-concept that requires further confirmation with the prospective study of a larger number of patients.
Assuntos
Antígenos de Neoplasias/imunologia , Autoanticorpos/imunologia , Neoplasias Renais/imunologia , Mimetismo Molecular , Síndromes Paraneoplásicas/imunologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Púrpura Trombocitopênica Idiopática/imunologia , Antígenos de Neoplasias/sangue , Autoanticorpos/sangue , Feminino , Humanos , Neoplasias Renais/sangue , Síndromes Paraneoplásicas/sangue , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Púrpura Trombocitopênica Idiopática/sangueRESUMO
Rationale: Platelets are increasingly recognized as mediators of tumor growth and metastasis. Hypothesizing that activated platelets in the tumor microenvironment provide a targeting epitope for tumor-directed chemotherapy, we developed an antibody-drug conjugate (ADC), comprised of a single-chain antibody (scFv) against the platelet integrin GPIIb/IIIa (scFvGPIIb/IIIa) linked to the potent chemotherapeutic microtubule inhibitor, monomethyl auristatin E (MMAE). Methods: We developed an ADC comprised of three components: 1) A scFv which specifically binds to the high affinity, activated integrin GPIIb/IIIa on activated platelets. 2) A highly potent microtubule inhibitor, monomethyl auristatin E. 3) A drug activation/release mechanism using a linker cleavable by cathepsin B, which we demonstrate to be abundant in the tumor microenvironment. The scFvGPIIb/IIIa-MMAE was first conjugated with Cyanine7 for in vivo imaging. The therapeutic efficacy of the scFvGPIIb/IIIa-MMAE was then tested in a mouse metastasis model of triple negative breast cancer. Results: In vitro studies confirmed that this ADC specifically binds to activated GPIIb/IIIa, and cathepsin B-mediated drug release/activation resulted in tumor cytotoxicity. In vivo fluorescence imaging demonstrated that the newly generated ADC localized to primary tumors and metastases in a mouse xenograft model of triple negative breast cancer, a difficult to treat tumor for which a selective tumor-targeting therapy remains to be clinically established. Importantly, we demonstrated that the scFvGPIIb/IIIa-MMAE displays marked efficacy as an anti-cancer agent, reducing tumor growth and preventing metastatic disease, without any discernible toxic effects. Conclusion: Here, we demonstrate the utility of a novel ADC that targets a potent cytotoxic drug to activated platelets and specifically releases the cytotoxic agent within the confines of the tumor. This unique targeting mechanism, specific to the tumor microenvironment, holds promise as a novel therapeutic approach for the treatment of a broad range of primary tumors and metastatic disease, particularly for tumors that lack specific molecular epitopes for drug targeting.
Assuntos
Antineoplásicos/administração & dosagem , Plaquetas/metabolismo , Imunoconjugados/administração & dosagem , Terapia de Alvo Molecular/métodos , Oligopeptídeos/administração & dosagem , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Microambiente Tumoral , Animais , Antineoplásicos/metabolismo , Modelos Animais de Doenças , Imunoconjugados/metabolismo , Camundongos , Metástase Neoplásica/tratamento farmacológico , Transplante de Neoplasias , Oligopeptídeos/metabolismo , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Complexo Glicoproteico GPIb-IX de Plaquetas/imunologia , Anticorpos de Cadeia Única/imunologia , Transplante Heterólogo , Resultado do TratamentoRESUMO
BACKGROUND: The main role of platelets is to control haemostasis when there is a blood vessel injury in order to minimise blood loss at the injury site. Under normal circumstances, platelets flow freely within blood vessels as the endothelial cells provide a non-adhesion surface. Naturally, bioactive mediators are released from endothelial cells to prevent and control platelet activation. However, when the vascular endothelium is ruptured, the local concentration of nitric oxide and prostaglandin is diminished and receptors containing a sequence of amino acids known as, immunoreceptor tyrosine-based inhibition motifs (ITIMs), serve as natural inhibitors within platelets. The main role of ITIMs is to decrease immunoreceptor tyrosine-based activation motif (ITAM) signalling in platelets; however, some studies have revealed their novel role in integrin αIIbß3 activation. This review highlights the main structural and functional features of immunoreceptors in platelets.