Prostasomes are extracellularly occurring submicron, membrane-surrounded organelles produced by the epithelial cells of the prostate and present in semen. Their precise physiological role is not known, although some of their properties assign them to important physiological and patho-physiological functions. In this thesis, some new properties of seminal and malignant cell line (DU145, PC-3 and LNCaP) prostasomes have been identified. Differences in the expressions and activities of prostasomal CD59, ATPase, protein kinases and tissue factor (TF) have been characterized. The transfer of prostasomal CD59 to CD59-deficient erythrocytes (rabbit and human PNH erythrocytes) has been established. CD59, protein kinases and TF were overexpressed by malignant cell prostasomes. ATPase activity was highest on seminal prostasomes with minimal expression by malignant cell prostasomes resulting in more residual ATP available for phosphorylation reactions. Several proteins were phosphorylated by prostasomal protein kinases, viz. complement component C3, fibrinogen, vitronectin and E-cadherin. Furthermore, TF was identified as the main endogenous phosphorylation substrate on prostasomes. In addition, prothrombotic effects of prostasomes were established. DU145 and PC-3-derived prostasomes exerted a higher clotting effect on whole blood and plasma compared to LNCaP and seminal prostasomes. In conclusion, malignant cell prostasomes showed higher ability to interact with the biological system in favor of prostate cancer cell promotion and survival. The roles played by prostasomes in this context may improve the understanding of the mechanisms that help the prostate cancer cells to avoid the complement attack (CD59 transfer and phosphorylation of C3), to promote angiogenesis (TF) and to metastasize. It may also provide a better understanding of some of the complications usually seen in some terminal prostate cancer patients like thrombotic events and tendency to develop disseminated intravascular coagulation.

BACKGROUND: Tissue factor (TF) is a 47 kDa transmembrane glycoprotein known as the main initiator of blood coagulation. CD40 ligand is another membrane molecule, which ligates to cell types associated with atherosclerotic plaques thereby mediating intraplaque inflammation and weakening of the fibrous cap. Acute coronary syndrome (ACS) is a multi-factorial disease in which TF and CD40 ligand have prominent roles. Single nucleotide poly-morphisms (SNPs) in the TF and CD40 ligand genes may influence the development, pro-gression and outcome in ACS. AIM: The aim of this thesis was to investigate the genetic and molecular control of TF expression in healthy individuals and in patients with ACS. More-over, the aim was to investigate whether SNPs in the TF and CD40L genes respectively were associated with risk and outcome in ACS and / or with plasma concentrations of these pro-teins. RESULTS: A real-time PCR method that allowed sensitive and dynamic quantification of TF mRNA was established and used for the identification of a high and low response phe-nomenon of TF mRNA. The TF high and low response correlated with the expression of toll-like receptor 4 (TLR-4) thus linking TF to innate immunity in a novel fashion. Investigation of several SNPs in the TF and CD40L genes led to the identification of the 5466 A>G in the TF gene and the -3459 A>G SNP in the CD40L gene. The 5466 G allele was associated with cardiovascular death in patients with ACS and increased TF procoagulant activity in human monocytes, which explained the clinical association. The -3459 G allele regulated the produc-tion of soluble CD40L but was not related with patient outcome. Soluble CD40L levels above median were associated with the risk of MI in patients with ACS. A prolonged treatment with dalteparin was more efficient in patients presenting with high levels of sCD40L, which further supports sCD40L as a marker of a prothrombotic state. CONCLUSIONS: The results of this thesis adds to our current knowledge of factors influencing TF expression and activity by demonstrating the effects of TF gene variants, cell signalling molecules, CD40 ligand protein and gene variation. All of these effects have the potential to modify the risk of development, progression and outcome in the acute coronary syndrome and exemplify the interplay between coagulation and inflammation, in which both TF and CD40 ligand are active.

Intraportal transplantation of isolated islets of Langerhans is a procedure approaching clinical acceptance as a treatment for patients with type I diabetes mellitus. One major problem with this treatment is that large amounts of cells are lost at the time of infusion into the portal vein, resulting in a low level of engraftment of the islets. One likely explanation for this loss is the instant blood-mediated inflammatory reaction (IBMIR), a thrombotic/inflammatory reaction occurring when islets come in contact with blood. The IBMIR is characterized by coagulation and complement activation, leading to platelet consumption, leukocyte infiltration of the islets, and disruption of islet integrity. In this thesis, the IBMIR is shown to be triggered by tissue factor (TF), the main initiator of blood coagulation in vivo. TF is expressed in two forms by the endocrine cells of the pancreas, a full-length membrane-bound and an alternatively spliced soluble form. Blocking TF in vitro efficiently reduces the macroscopic clotting, expression of coagulation activation markers, and leukocyte infiltration. This blockade can be achieved by adding either an active site-specific anti-TF antibody or site-inactivated FVIIa that competes with active FVIIa in the blood. TF may be secreted from the islets, since it is colocalized with insulin and glucagon in their granules. The IBMIR has also been demonstrated in vivo in patients transplanted with isolated islets. There are two ways to block the IBMIR in transplantation: systemic treatment of the patients, or islet pretreatment before transplantation to reduce their thrombogenicity. In this thesis, low molecular weight dextran sulfate (LMW-DS) is shown to reduce activation of the complement and coagulation systems and decrease the cell infiltration into the islets in vitro and in vivo, in both a xenogenic and an allogenic setting. Based on these results, LMW-DS is now in clinical trials.

Tissue factor (TF) is a transmembrane glycoprotein that initiates the blood coagulation cascade and is also involved in cell migration, tumour metastasis and angiogenesis. Pathologic expression of tissue factor by monocytes contributes to several thrombotic complications like acute coronary artery disease and disseminated intravascular coagulation. The aim of this thesis was to investigate the clinically important pathologic expression of TF in myelo-monocytic leukaemia cells and reveal the cellular signals leading to the suppression of TF expression. The studies in this thesis indicate that TF is a marker of immature myelo-monocytic cells. Markedly higher levels of TF were expressed in immature myelo-monocytic cell lines compared to mature monocyte-like cells. Induction of terminal differentiation in immature cells resulted in down-regulation of TF expression, irrespective of the specific phenotypes induced by retinoic acid (RA) or vitamin D3 in monoblastic U-937 cells. TF suppression was also found independent of differentiation pathways, i.e. monocytic or granulocytic. The nuclear receptor activation requirements for transcriptional suppression of TF by retinoic acid (RA) were shown to differ between acute promyelocytic leukaemia (APL) NB4 and U-937 cells. In NB4 cells the binding of the agonist to the RA receptor (RAR)α alone is needed for down-regulation of TF, whereas ligand binding to both RARαand retinoic X receptor was necessary for efficient suppression of TF expression in U-937 cells. To analyse the transcriptional regulation of TF, stable NB4 and U-937 clones expressing the luciferase gene under the control of various 5' flanking regions of the TF gene were selected. Different promoter regions were found to control the basal TF transcriptional activity. Analysis of protein binding to the 140 bp promoter region, responsible for basal TF activity in NB4 cells, revealed binding of RFX-1. RA suppressed the promoter activity in NB4, but not in U-937 cells. The ectopic expression of the APL fusion proteins PML/RARα or PLZF/RARα in U-937 reporter clones were shown to confer sensitivity to RA-induced suppression of TF promoter activity. These results provide a more detailed picture of TF regulation in leukaemic and haematopoietic cells and may have a bearing on new clinical treatment strategies in APL and other leukaemias.

It has been postulated that the control of thrombus formation on molecularly engineered surfaces is an important step in developing clinically durable small-diameter vascular prostheses. This has led to designing a membrane-mimetic assembly that contains physiological regulators of blood coagulation, thrombomodulin (TM) and heparin, to provide strategies for generating actively antithrombogenic surfaces. The membrane-mimetic construct contains polymeric phospholipid monolayer on an alkylated polyelectrolyte multilayer supported by planar substrate such as glass or silicone. When incorporated with TM, the model platform exhibited the biological function by catalyzing activation of protein C. Surface TM activity was extensively investigated at physiologic shear rates (50 sec-1 and 500 sec-1). Significantly, reaction rates become saturated at TM surface densities greater than or equal to ~ 800 fmole/cm2 due to due to a transport limitation. Based on the similar membrane-mimetic construct, a functional heparinized surface was designed as an alternative anticoagulant system. Immobilization of heparin onto membrane-mimetic surfaces was achieved through biotin-streptavidin binding specificity. Activity of surface heparin to facilitate thrombin inactivation was investigated at shear rates of 50 and 500 sec-1. Significantly, rate of thrombin decay becomes saturated when the surface coverage of heparin is higher than 4.4 pmole of heparin per cm2. We further investigated the effects of surface bound TM and heparin on tissue factor (TF) -induced thrombin generation in a flow model. Specifically, TF positioned over a 2 x 6 mm2 upstream region as a trigger for thrombin generation and TM and/or heparin positioned over the remaining downstream (34 x 6 mm2) portion of the test film. Compared to TF alone surface, thrombin generation was profoundly reduced in the presence of surface bound TM and/or heparin. Significantly, thrombin production was maximally inhibited more than 85% in the presence of TM and heparin, possibly due to anticoagulant synergism of both anticoagulants. We believe that current membrane-mimetic systems can potentially create actively antithrombogenic surfaces.

A mathematical model of blood coagulation under defined flow conditions, initiated and modulated by spatially discrete regions of surface bound tissue factor (TF) and thrombomodulin (TM), respectively, is presented. The model incorporates fluid phase and surface-associated reactions of the extrinsic, intrinsic, and common pathways, as well as three inhibitory pathways. The spatially heterogeneous model is formulated by finite element method, and an effective prothrombotic zone, which quantifies the spatial propagation of thrombin generation is defined. Characteristic features of coagulation are simulated under physiologic conditions, and the behavior of the system in response to perturbations in TF and TM surface densities, TF site dimensions, and wall shear rate is explored. The major findings of these studies include: (i) The model system responds in an 'all-or-none', threshold-like manner to changes in model parameters. (ii) It was found that prothrombotic effects may extend significantly beyond the dimensions of the spatially discrete site of TF expression in both axial and radial directions. (iii) The relationship between the length of the effective prothrombotic zone and the interval distance between tandem sites of TF expression dictate the net response of the system. Additive prothrombotic effects of sub-clinical lesions as well as suppressive antithrombotic effects of intervening TM-containing regions were observed. Secondly, the computational model is applied to calculate an individualized, systems-based metric of clotting potential for 210 pre-menopausal women in the Leiden Thrombophilia Study (LETS). The simulated variable was found to be a highly predictive parameter for deep venous thrombosis risk.

Para avaliar a capacidade da toxina ExoU de P. aeruginosa de induzir a expressão do fator tissular (FT) por células epiteliais respiratórias da linhagem BEAS-2B, células infectadas pela cepa PA103, produtora da toxina, foram comparadas com outras infectadas por cepa mutante obtida por deleção do gene exoU e com células controles não infectadas quanto a i) expressão do mRNA do FT, por RT-PCR; ii) expressão da proteína FT em lisados celulares, por ensaio imunoenzimático (ELISA), e na superfície celular, por citometria de fluxo; iii) atividade pró-coagulante das células, pela determinação da capacidade de indução de coagulação de plasma humano normal e do lisado celular, através de ensaio colorimétrico; iv) presença de FT solúvel no sobrenadante das culturas, por ELISA; v) liberação de micropartículas expressando FT e fosfatidilserina (FS), por citometria de fluxo. Nossos resultados mostraram que ExoU foi responsável pelo aumento da expressão do mRNA e da concentração da glicoproteína FT tanto nos lisados quanto na superfície celular. Esse aumento foi revertido quando as bactérias foram tratadas com uma droga inibidora de PLA2 (MAFP), comprovando-se a dependência da atividade fosfolipásica A2 de ExoU para a modulação da expressão do FT. Células infectadas pela cepa PA103 induziram uma diminuição no tempo de coagulação do plasma humano normal e o aumento da hidrólise do substrato sintético utilizado no teste colorimétrico em comparação com as células infectadas com a cepa mutante, mostrando que o FT expresso era funcionalmente ativo. Foi também detectado um aumento na concentração de FT solúvel presente nos sobrenadantes de culturas infectadas por PA103 e no número de micropartículas expressando, simultaneamente, FT e FS em relação à cultura infectada pela cepa PA103∆exoU. Os resultados obtidos nos testes in vitro foram validados pela demonstração de que a concentração de FT no parênquima pulmonar de camundongos infectados, por via intratraqueal, com a cepa selvagem foi significativamente superior à detectada nos animais infectados com a cepa mutante. / To evaluate the capacity of the P. aeruginosa toxin ExoU to induce the expression of tissue factor (TF) by epithelial respiratory cells from the BEAS-2B cell line, cells infected with the ExoU-producing PA103 bacterial strain were compared with cells infected with a mutant obtained by deletion of the exoU gene and with control non-infected cells in their i) expression of the TF mRNA, by RT-PCR; ii) expression of the protein TF in cell lisates and surfaces, by enzyme immunoassay (ELISA) and flow cytometry, respectively; iii) procoagulant activity by determining the ability of intact cells to induce the coagulation of normal human plasma and the ability of cell lysates to cleave the synthetic substrate of a chromogenic assay; iv) presence of soluble TF in cell culture supernatants, by ELISA and v) release of microparticles simultaneously expressing TF and phosphatidylserine, by flow cytometry. Cells infected with the wild type bacteria exhibited increased expression of TF mRNA 1 hour after infection and a positive modulation of TF expression in both cell lysates and cell surfaces. The enhancement of TF expression was inhibited when cells were infected with bacteria previously treated with a PLA2 inhibitor (MAFP), confirming that the ability of ExoU to modulate TF expression depended on its phospholipase A2 activity. Newly expressed TF was shown to be functionally active, by both the decrease in the clotting time of human plasma and the enhancement of the hydrolysis of the chromogenic assay substrate. Cells infected with the ExoU-producing bacteria exhibited also higher concentrations of soluble TF and of TF and PS bearing microparticles in the cell culture supernatants. These in vitro results were validated by our finding of increase TF concentrations in the lung parenchyma of mice infected intratracheally with the ExoU producing-bacteria at 24 h post-infection.

Para avaliar a capacidade da toxina ExoU de P. aeruginosa de induzir a expressão do fator tissular (FT) por células epiteliais respiratórias da linhagem BEAS-2B, células infectadas pela cepa PA103, produtora da toxina, foram comparadas com outras infectadas por cepa mutante obtida por deleção do gene exoU e com células controles não infectadas quanto a i) expressão do mRNA do FT, por RT-PCR; ii) expressão da proteína FT em lisados celulares, por ensaio imunoenzimático (ELISA), e na superfície celular, por citometria de fluxo; iii) atividade pró-coagulante das células, pela determinação da capacidade de indução de coagulação de plasma humano normal e do lisado celular, através de ensaio colorimétrico; iv) presença de FT solúvel no sobrenadante das culturas, por ELISA; v) liberação de micropartículas expressando FT e fosfatidilserina (FS), por citometria de fluxo. Nossos resultados mostraram que ExoU foi responsável pelo aumento da expressão do mRNA e da concentração da glicoproteína FT tanto nos lisados quanto na superfície celular. Esse aumento foi revertido quando as bactérias foram tratadas com uma droga inibidora de PLA2 (MAFP), comprovando-se a dependência da atividade fosfolipásica A2 de ExoU para a modulação da expressão do FT. Células infectadas pela cepa PA103 induziram uma diminuição no tempo de coagulação do plasma humano normal e o aumento da hidrólise do substrato sintético utilizado no teste colorimétrico em comparação com as células infectadas com a cepa mutante, mostrando que o FT expresso era funcionalmente ativo. Foi também detectado um aumento na concentração de FT solúvel presente nos sobrenadantes de culturas infectadas por PA103 e no número de micropartículas expressando, simultaneamente, FT e FS em relação à cultura infectada pela cepa PA103∆exoU. Os resultados obtidos nos testes in vitro foram validados pela demonstração de que a concentração de FT no parênquima pulmonar de camundongos infectados, por via intratraqueal, com a cepa selvagem foi significativamente superior à detectada nos animais infectados com a cepa mutante. / To evaluate the capacity of the P. aeruginosa toxin ExoU to induce the expression of tissue factor (TF) by epithelial respiratory cells from the BEAS-2B cell line, cells infected with the ExoU-producing PA103 bacterial strain were compared with cells infected with a mutant obtained by deletion of the exoU gene and with control non-infected cells in their i) expression of the TF mRNA, by RT-PCR; ii) expression of the protein TF in cell lisates and surfaces, by enzyme immunoassay (ELISA) and flow cytometry, respectively; iii) procoagulant activity by determining the ability of intact cells to induce the coagulation of normal human plasma and the ability of cell lysates to cleave the synthetic substrate of a chromogenic assay; iv) presence of soluble TF in cell culture supernatants, by ELISA and v) release of microparticles simultaneously expressing TF and phosphatidylserine, by flow cytometry. Cells infected with the wild type bacteria exhibited increased expression of TF mRNA 1 hour after infection and a positive modulation of TF expression in both cell lysates and cell surfaces. The enhancement of TF expression was inhibited when cells were infected with bacteria previously treated with a PLA2 inhibitor (MAFP), confirming that the ability of ExoU to modulate TF expression depended on its phospholipase A2 activity. Newly expressed TF was shown to be functionally active, by both the decrease in the clotting time of human plasma and the enhancement of the hydrolysis of the chromogenic assay substrate. Cells infected with the ExoU-producing bacteria exhibited also higher concentrations of soluble TF and of TF and PS bearing microparticles in the cell culture supernatants. These in vitro results were validated by our finding of increase TF concentrations in the lung parenchyma of mice infected intratracheally with the ExoU producing-bacteria at 24 h post-infection.

Introdução: Pacientes com Doença de Crohn (DC) apresentam alto risco de eventos tromboembólicos (TE), muitas vezes, associados a alta morbimortalidade. É conhecido o papel da inflamação na fisiopatologia da trombose na doença Inflamatória Intestinal (DII), entretanto, o significado da inflamação subclínica ainda se mantém obscuro na literatura. Este estudo avaliou o efeito da atividade endoscópica no perfil de coagulação dos pacientes com DC em remissão clínica. Métodos: entre os dias 22 de maio de 2015 e 26 de abril de 2017, foram triados 261 pacientes com DC em possível remissão clínica, sendo realizadas ao todo 229 colonoscopias. Das 229 colonoscopias realizadas, 164 pacientes estavam realmente em remissão clínica (confirmados com CDAI <= 150) e foram alocados em dois grupos: 75 no grupo de atividade endoscópica (AE) (SES-CD >= 7), 89 no grupo de remissão endoscópica (RE) (SES-CD <= 2). Cinquenta controles saudáveis pareados por sexo e idade foram eleitos. Medimos, nos 3 grupos, além da geração de trombina - pelo método Calibrated Automated Thrombogram (CAT), com e sem trombomodulina, - a atividade do fator tecidual (FT), fibrinogênio, D-dímero, Fator VIII, ADAMTS-13, Fator de von Willebrand - antígeno e cofator de ristocetina (cWF). Coletamos dados sobre a duração da doença, extensão, comportamento, localização, tratamento farmacológico, história prévia de cirurgias, calprotectina fecal, qualidade de vida (por meio do IBDQ), além dos fatores de risco para TE, como hospitalização recente, uso de corticoide atual, status do tabagismo, assim como marcadores de trombofilia hereditária ou adquirida. Seguimos os pacientes por 1 ano de observação, avaliando a variação no CDAI e IBDQ no período. Resultados: A maioria dos pacientes apresentou comprometimento ileocolônico (43%), com comportamento inflamatório (40%), seguido de estenosante (30%) e fistulizante (30%). 67% estavam em uso de imunossupressores e 52% em uso de biológicos. Os fatores de risco para TE e todos os outros marcadores de trombofilia, incluindo deficiência de proteína C e S, anticardiolipina, resistência à proteína C, antitrombina, mutações da protrombina e do Fator V, foram semelhantes em ambos os grupos, exceto pelo anticoagulante lúpico, maior no grupo de AE (8,1% vs. 1,3%, p=0,047). Como esperado, o grupo de AE apresentou níveis significativamente maiores de PCR, calprotectina fecal e plaquetas. Além disso, este grupo apresentou uma maior atividade do fator tecidual vs. o grupo de RE vs. controles (127 vs. 103 vs. 84, p = 0,001). Embora o grupo DC tivesse maiores níveis de FVW:Ag e FVW:RCo, FVW/ADAMTS-13, Fator VIII e trombomodulina vs. controles, não houve diferença estatística entre os grupos de AE e RE. Os níveis de geração de trombina foram semelhantes entre os 3 grupos, com ou sem trombomodulina. Conclusão: Esses dados evidenciam que existe uma disfunção endotelial inerente à DC, e, que, em pacientes com AE, essa disfunção pode ser ainda maior pela maior exposição do FT. Embora, a presença de inflamação e dano endotelial contribuam para esse estado procoagulante, em pacientes com doença subclínica, há um estado de compensação permanente, uma vez que a quantidade de trombina gerada foi a mesma entre os grupos. Este equilíbrio pode estar comprometido diante de outros fatores tromboembólicos, aumentando, assim, o risco de trombose / Background: Crohn\'s disease patients (CD) have a high risk of thromboembolic events (TE), often associated with high morbidity and mortality. Involvement of inflammation in TE is well known, but significance of the sub-clinical inflammation in this process is not the rule. Thus, the aim of this study is to evaluate the effect of the endoscopic activity in the coagulation profile in CD in clinical remission. Methods: Between May/2015 and April/2017, 261 CD patients in supposed clinical remission, were screened, and 229 had a colonoscopy done, resulting in the inclusion of 164 CD patients in clinical remission confirmed by a CDAI <= 150. They were allocated in two groups: 75 in the endoscopic activity (EA) group (SES-CD >= 7), and 89 in the endoscopic remission (ER) group (SES-CD <= 2). 50 healthy controls matched for sex and age were chosen. We measured in the 3 groups, in addition to the generation of thrombin - through the Calibrated Automated Thrombogram (CAT), with and without thrombomodulin, - the activity of tissue factor (TF), fibrinogen, D-dimer, Factor VIII, ADAMTS-13 and von Willebrand Factor - antigen (VWF) and ristocetin cofactor (VWF:RCo). We collected data regarding the duration of the disease, extension, behavior, location, pharmacological treatment, previous history of surgeries, fecal calprotectin, quality of life (through IBDQ), as well as risk factors for TE such as recent hospitalization, current corticoid use, smoking status, as well as markers of hereditary or acquired thrombophilia. We followed the patients for 1 year of observation, evaluating the variation in CDAI and IBDQ. Results: Most of the patients had ileocolonic involvement (43%), with inflammatory behavior (40%), followed by stenosing (30%) and fistulizing (30%). 67% were in use of immunosuppressors and 52% in use of biological drugs. Risk factors for TE besides other markers of thrombophilia, including protein C and S deficiency, anticardiolipin, protein C resistance, antithrombin, prothrombin and Factor V mutations, were similar in both groups except for the lupus anticoagulant, higher in the EA group (8.1% vs. 1.3%, p = 0.047). As expected, the EA group had significantly higher levels of CRP, fecal calprotectin and platelets. In addition, this group had a higher activity of TF vs. ER group vs. controls (127 vs. 103 vs. 84, p = 0.001). Although the DC group had had higher levels of VWF and VWF:RCo, VWF/ADAMTS-13, Factor VIII and thrombomodulin vs. controls, there was no statistical difference between the EA and ER groups. Thrombin generation levels were similar between the 3 groups, with or without thrombomodulin. Conclusion: These data show that there is an inherent endothelial dysfunction in CD, moreover in patients with EA, this dysfunction may be even greater, due to the exposure of TF. Although the presence of inflammation and endothelial damage contribute to this procoagulant condition, in patients with subclinical disease, there is a permanent compensatory state, since the amount of thrombin generated was the same between the groups. This balance may be compromised by other thromboembolic factors, thus increasing the risk of thrombosis

Le cancer colorectal (CRC) est le plus fréquent des cancers digestifs. Cependant, il est moins grave et moins fréquemment associé à une complication thrombo-embolique que le cancer du pancréas (PC). Les microparticules (MPs) sont de petites vésicules produites par bourgeonnement de la membrane cellulaire. Les MPs sont impliquées dans la croissance tumorale, le développement de métastases et l’activité pro-coagulante associée aux cancers. Les objectifs de ces travaux étaient d’identifier et de caractériser les différentes MPs dans le CRC and le PC, afin de décrire une signature microparticulaire, puis d’évaluer leur implication dans la survenue de complications thrombo-emboliques. Nous avons donc rapporté une signature microparticulaire spécifique dans le CRC et le PC par rapport à des pathologies bénignes colorectales et pancréatiques, ainsi que des sujets sains, que nous avons appelé “microparticulosome”. Le microparticulosome se modifie avec l’évolution de la maladie, pour se rapprocher des formes bénignes voire des sujets sains, en cas de rémission du CRC. De plus,il varie en présence ou non d'une complication thrombo-embolique. Nous avons également rapporté le cas d’un cancer du sein diagnostiqué grâce à des taux élevés de MPs exprimant la fibrine. En conclusion, les MPs pourraient constituer de nouveaux bio-marqueurs pertinents en cancérologie, dans le diagnostic, le pronostic de survie et de survenue d’une complication thrombo-embolique. La connaissance des interactions des MPs avec le microenvironnement tumoral permettra de mettre au point des thérapeutiques adaptées et efficaces dans la croissance tumorale et l’extension métastatique. / Colorectal cancer (CRC) is the most common gastrointestinal cancer. It is less serious and less frequently associated with thrombo-embolic event than pancreatic cancer (PC). Microparticles (MPs) are small vesicles produced and released by exocytic blebbing of the activated and apoptotic cell membrane from most, if not all, types of cells. They are known to be implicated in the tumor growth, the development of metastases and the cancer-associated procoagulant activity. Our objectives were to identify and to characterize the different concentrations of circulating MPs in CRC and PC, in order to describe a MPs hallmark, and to evaluate their implication in the occurrence of a venous thromboembolism. We have thus reported a specific hallmark of MPs in CRC and PC, comparing to benign colorectal and pancreatic diseases and healthy subjects, so-called the “microparticulosome”. We have observed that microparticulosome changed with the evolution of the disease, and tended to the signature observed for benign diseases or healthy subject in case of CRC remission. We also reported variations in the microparticulosome in case of an occurrence of a thrombo-embolic event.In conclusion, MPs may constitute new pertinent biomarkers in cancers, in the diagnosis, the survival prognostic and the prognostic of the occurrence of thrombo-embolic events. Understanding the interactions of MPs with tumor environment will allow to find efficient treatments against tumor growth and metastases development.