MeVa2.1.dOVA and MeVa2.2.dOVA: two novel BRAFV600E-driven mouse melanoma cell lines to study tumor immune resistance.

While immunotherapy has become standard-of-care for cutaneous melanoma patients, primary and acquired resistance prevent long-term benefits for about half of the late-stage patients. Pre-clinical models are essential to increase our understanding of the resistance mechanisms of melanomas, aiming to improve the efficacy of immunotherapy. Here, we present two novel syngeneic transplantable murine melanoma cell lines derived from the same primary tumor induced on BrafV600E Pten-/- mice: MeVa2.1 and MeVa2.2. Derivatives of these cell lines expressing the foreign antigen ovalbumin (dOVA) showed contrasting immune-mediated tumor control. MeVa2.2.dOVA melanomas were initially controlled in immune-competent hosts until variants grew out that had lost their antigens. By contrast, MeVa2.1.dOVA tumors were not controlled despite presenting the strong OVA antigen, as well as infiltration of tumor-reactive CD8+ T cells. MeVa2.1.dOVA displayed reduced sensitivity to T cell-mediated killing and growth inhibition in vitro by both IFN-γ and TNF-α. MeVa2.1.dOVA tumors were transiently controlled in vivo by either targeted therapy, adoptive T cell transfer, regulatory T cell depletion, or immune checkpoint blockade. MeVa2.1.dOVA could thus become a valuable melanoma model to evaluate novel immunotherapy combinations aiming to overcome immune resistance mechanisms.

Obesidade infantil em tempos de pandemia: uma revisão integrativa / Childhood obesity in pandemic times: an integrative review / Obesidad infantil en tiempos de pandemia: una revisión integradora

A obesidade é considerada um dos maiores problemas de saúde pública mundial, sendo caracterizada como uma epidemia global, e durante a pandemia de COVID-19, o isolamento social e as mudanças nos hábitos de vida podem ter influenciado para o aumento dos índices de obesidade em crianças e adolescentes. Assim, o objetivo do estudo é analisar na literatura de que forma a pandemia de COVID-19 pode ter influenciado no aumento da obesidade infantil. Trata-se de uma revisão integrativa da literatura, com busca feita nas bases de dados Cinahl, PubMed e Scopus, com uso de descritores e booleanos aplicados em cada base de dados. Ao todo 14 estudos foram incluídos nesta revisão. A maioria dos estudos tinha ênfase avaliação de intervenções, bem como comparação das taxas de obesidade antes e durante a pandemia, e os efeitos dessas mudanças a longo prazo. Além de enfatizar sobre a participação dos pais e a construção de políticas públicas no combate à epidemia global de obesidade infantil. A pandemia contribuiu para o aumento de casos de sobrepeso e obesidade, bem como agravou os casos de crianças que já apresentavam tais características. Desta forma compreender sobre a situação desse problema de saúde, após um longo período de confinamento, pode auxiliar e engajar os profissionais da saúde na construção e estabelecimento de estratégias no combate da obesidade infantil e incentivar a participação dos pais na promoção de mudanças no estilo de vida.

Obesity is considered a major public health problem worldwide, being characterized as a global epidemic, and during the COVID-19 pandemic, social isolation and changes in lifestyle habits may have influenced the increase in obesity rates in children and adolescents. Thus, the purpose of the study is to analyze in the literature how the COVID-19 pandemic may have influenced the increase in childhood obesity. This is an integrative literature review, with a search conducted in the Cinahl, PubMed, and Scopus databases, with the use of descriptors and booleans applied in each database. A total of 14 studies were included in this review. Most of the studies had an emphasis on evaluation of interventions, as well as comparison of obesity rates before and during the pandemic, and the long-term effects of these changes. In addition to emphasizing on parent participation and building public policy to combat the global epidemic of childhood obesity. The pandemic contributed to the increase of overweight and obesity cases, as well as worsened the cases of children who already presented such characteristics. Thus, understanding the situation of this health problem after a long period of confinement can help and engage health professionals in the construction and establishment of strategies to combat childhood obesity and encourage parental participation in promoting lifestyle changes.

La obesidad es considerada un importante problema de salud pública a nivel mundial, caracterizándose como una epidemia mundial, y durante la pandemia de COVID-19, el aislamiento social y los cambios en los hábitos de vida pueden haber influido en el aumento de las tasas de obesidad en niños y adolescentes. Así, el propósito del estudio es analizar en la literatura cómo la pandemia de COVID-19 pudo haber influido en el aumento de la obesidad infantil. Esta es una revisión integrativa de la literatura, con una búsqueda realizada en las bases de datos Cinahl, PubMed y Scopus, con el uso de descriptores y booleanos aplicados en cada base de datos. En esta revisión se incluyeron un total de 14 estudios. La mayoría de los estudios hicieron hincapié en la evaluación de las intervenciones, así como en la comparación de las tasas de obesidad antes y durante la pandemia, y los efectos a largo plazo de estos cambios. Además de enfatizar en la participación de los padres y construir políticas públicas para combatir la epidemia mundial de obesidad infantil. La pandemia ha contribuido al aumento de los casos de sobrepeso y obesidad, así como al empeoramiento de los casos de niños que ya presentan tales características. Por lo tanto, comprender la situación de este problema de salud después de un largo período de encierro puede ayudar y comprometer a los profesionales de la salud en la construcción y establecimiento de estrategias para combatir la obesidad infantil y fomentar la participación de los padres en la promoción de cambios en el estilo de vida.

Recombinant human DNase I for the treatment of cancer-associated thrombosis: A pre-clinical study.

Cancer patients are more likely to develop thrombosis, and this co-morbidity is related to the worse prognosis of the disease. The increased formation of neutrophil extracellular traps (NETs) has been proposed as one of the mechanisms to explain cancer-associated thrombosis. In vivo, degradation of NETs with recombinant human DNase I (rhDNase I) prevents thrombus formation in mouse models. In this work, we evaluated the effect of two different chronic treatments with rhDNase I in a murine NET-dependent prothrombotic state in breast cancer model. Medium-term treatment (2.5 mg/kg rhDNase I for eight consecutive days) did not interfere with the primary growth of 4T1 tumors. On the other hand, it effectively prevented thrombus formation in the inferior vena cava stenosis model. Remarkably, medium-term treatment with rhDNase I showed minor impact in the tail-bleeding model. Different from the medium-term, the long-term treatment with rhDNase I (2.5 mg/kg for 18 successive days) drastically reduced the overall survival. Remarkably, the concomitant use of Ertapenem, a carbapenem antibiotic, and rhDNase I significantly attenuated the mortality observed in the long-term treatment. Our results suggest the therapeutic potential of rhDNase I to treat cancer-associated thrombosis, although its chronic use should be carefully evaluated and potentially harmful.

Development of 131I-ixolaris as a theranostic agent: metastatic melanoma preclinical studies.

Tissue factor (TF), a blood coagulation protein, plays an important role in tumor growth, invasion, and metastasis. Ixolaris, a tick-derived non-immunogenic molecule that binds to TF, has demonstrated in vivo inhibitory effect on murine models of melanoma, including primary growth and metastasis. This work aimed to: I) develop an efficient and stable labeling technique of ixolaris with Iodine-131(131I); II) compare the biodistribution of 131I and 131I-ixolaris in tumor-free and melanoma-bearing mice; III) evaluate whether 131I-ixolaris could serve as an antimetastatic agent. Ixolaris radioiodination was performed using iodogen, followed by liquid paper chromatography. Labeling stability and anticoagulant activity were measured. Imaging studies were performed after intravenous administration of free 131I or 131I-ixolaris in a murine melanoma model employing the B16-F10 cell line. Animals were divided in three experimental groups: the first experimental group, D0, received a single-dose of 9.25 MBq of 131I-ixolaris at the same day the animals were inoculated with melanoma cells. In the second group, D15, a single-dose of 9.25 MBq of 131I-ixolaris or free 131I was applied into mice on the fifteenth day after the tumor induction. The third group, D1-D15, received two therapeutic doses of 9.25 MBq of 131I-ixolaris or 131I. In vitro studies demonstrated that 131I-ixolaris is stable for up to 24 h and retains its inhibitory activity on blood coagulation. Biodistribution analysis and metastasis assays showed that all treatment regimens with 131I-ixolaris were effective, being the double-treatment (D1/D15) the most effective one. Remarkably, treatment with free 131I showed no anti-metastatic effect. 131I-ixolaris is a promising theranostic agent for metastatic melanoma.

IL-1ß Blockade Attenuates Thrombosis in a Neutrophil Extracellular Trap-Dependent Breast Cancer Model.

Cancer patients are at increased risk of developing thrombosis, comorbidity that has been associated with increased neutrophil counts and the formation of neutrophil extracellular traps (NETs). Interleukin-1ß (IL-1ß) modulates the expression of granulocyte colony-stimulating factor (G-CSF), a cytokine that promotes cancer-associated neutrophilia and NET generation. Herein, we combined a murine breast cancer model with a flow-restriction thrombosis model to evaluate whether the IL-1ß blockade could interfere with cancer-associated thrombosis. Mice bearing metastatic 4T1 tumors exhibited high neutrophil counts as well as elevated expression of G-CSF and IL-1ß in their tumors. On the other hand, mice bearing non-metastatic 67NR tumors showed no elevation in neutrophil counts and displayed low expression levels of G-CSF and IL-1ß in their tumors. 4T1 tumor-bearing mice but not 67NR tumor-bearing mice exhibited a NET-dependent prothrombotic state. Pharmacological blockade of IL-1 receptor (IL-1R) decreased the primary growth of 4T1 tumors and reduced the systemic levels of myeloperoxidase, cell-free DNA (cfDNA) and G-CSF, without interfering with the neutrophil counts. Most remarkably, the blockade of IL-1R abolished the prothrombotic state observed in 4T1 tumor-bearing mice. Overall, our results demonstrate that IL-1ß might be a feasible target to attenuate cancer-associated thrombosis, particularly in cancer types that rely on increased G-CSF production and involvement of NET formation.

Novel Aspects of Extracellular Vesicles as Mediators of Cancer-Associated Thrombosis.

The establishment of prothrombotic states during cancer progression is well reported but the precise mechanisms underlying this process remain elusive. A number of studies have implicated the presence of the clotting initiator protein, tissue factor (TF), in circulating tumor-derived extracellular vesicles (EVs) with thrombotic manifestations in certain cancer types. Tumor cells, as well as tumor-derived EVs, may activate and promote platelet aggregation by TF-dependent and independent pathways. Cancer cells and their secreted EVs may also facilitate the formation of neutrophil extracellular traps (NETs), which may contribute to thrombus development. Alternatively, the presence of polyphosphate (polyP) in tumor-derived EVs may promote thrombosis through a TF-independent route. We conclude that the contribution of EVs to cancer coagulopathy is quite complex, in which one or more mechanisms may take place in a certain cancer type. In this context, strategies that could attenuate the crosstalk between the proposed pro-hemostatic routes could potentially reduce cancer-associated thrombosis.

H+-dependent inorganic phosphate transporter in breast cancer cells: Possible functions in the tumor microenvironment.

Tumor microenvironment has a high concentration of inorganic phosphate (Pi), which is actually a marker for tumor progression. Regarding Pi another class of transporter has been recently studied, an H+-dependent Pi transporter, that is stimulated at acidic pH in Caco2BBE human intestinal cells. In this study, we characterized the H+-dependent Pi transport in breast cancer cell (MDA-MB-231) and around the cancer tissue. MDA-MB-231 cell line presented higher levels of H+-dependent Pi transport as compared to other breast cell lines, such as MCF-10A, MCF-7 and T47-D. The Pi transport was linear as a function of time and exhibited a Michaelis-Menten kinetic of Km = 1.387 ±â€¯0.1674 mM Pi and Vmax = 198.6 ±â€¯10.23 Pi × h-1 × mg protein-1 hence reflecting a low affinity Pi transport. H+-dependent Pi uptake was higher at acidic pH. FCCP, Bafilomycin A1 and SCH28080, which deregulate the intracellular levels of protons, inhibited the H+-dependent Pi transport. No effect on pHi was observed in the absence of inorganic phosphate. PAA, an H+-dependent Pi transport inhibitor, reduced the Pi transport activity, cell proliferation, adhesion, and migration. Arsenate, a structural analog of Pi, inhibited the Pi transport. At high Pi conditions, the H+-dependent Pi transport was five-fold higher than the Na+-dependent Pi transport, thus reflecting a low affinity Pi transport. The occurrence of an H+-dependent Pi transporter in tumor cells may endow them with an alternative path for Pi uptake in situations in which Na+-dependent Pi transport is saturated within the tumor microenvironment, thus regulating the energetically expensive tumor processes.

Management challenges for best practices of the Kangaroo Method in the Neonatal ICU.

OBJECTIVE: To understand the conditions that influence the adherence and application of best practices by nurses in the context of the Nursing care management in the Kangaroo Mother Care in the Neonatal ICU. METHOD: Study of qualitative approach, whose theoretical and methodological frameworks were Symbolic Interactionism and Grounded Theory, respectively. We used the in-depth interview with 8 nurses from the Neonatal ICU of a public maternity hospital in the city of Rio de Janeiro. RESULTS: The conditions involved in adhering to the best practices of humanization in the Neonatal ICU are related mainly to human resources, interaction among professionals, work processes and leadership strategies; and care management. CONCLUSION: Professional and institutional challenges have been identified that need to be addressed to improve adherence and implementation of the Kangaroo Mother Care best practices.

Tissue factor mediates microvesicles shedding from MDA-MB-231 breast cancer cells.

Extracellular vesicles, such as microvesicles (MVs), were identified as important players in tumor progression and acquisition of an aggressive phenotype. Tissue factor (TF) is a transmembrane protein that initiates the blood coagulation cascade. In tumor cells, TF has been associated with aggressiveness and cancer progression. Previous studies demonstrate that TF is incorporated into MVs secreted by tumor cells; however, it is unknown whether TF is actively involved in the release of MVs. Here, we investigated the influence of TF expression on the release of MVs. TF silencing was achieved through CRISPR/Cas9 approaches in the human breast cancer cell line, MDA-MB-231. TF knockout in MDA-MB-231 cells efficiently reduced TF-dependent signaling and procoagulant activity. Remarkably, silencing of TF caused a significant decrease in the number of MVs released by MDA-MB-231 cells. We also observed an increase in actin-positive membrane projections in TF knockout cells and a reduction in RhoA expression when compared to TF-expressing cells. Treatment of MDA-MB-231 cells with the RhoA-ROCK signaling pathway inhibitor, fasudil, significantly reduced the release of MVs. Taken together, our results suggest a novel and relevant role for TF in tumor biology by playing an active role in the MVs secretion.

Characterization of inorganic phosphate transport in the triple-negative breast cancer cell line, MDA-MB-231.

BACKGROUND: Recent studies demonstrate that interstitial inorganic phosphate is significantly elevated in the breast cancer microenvironment as compared to normal tissue. In addition it has been shown that breast cancer cells express high levels of the NaPi-IIb carrier (SLC34A2), suggesting that this carrier may play a role in breast cancer progression. However, the biochemical behavior of inorganic phosphate (Pi) transporter in this cancer type remains elusive. METHODS: In this work, we characterize the kinetic parameters of Pi transport in the aggressive human breast cancer cell line, MDA-MB-231, and correlated Pi transport with cell migration and adhesion. RESULTS: We determined the influence of sodium concentration, pH, metabolic inhibitors, as well as the affinity for inorganic phosphate in Pi transport. We observed that the inorganic phosphate is dependent on sodium transport (K0,5 value = 21.98 mM for NaCl). Furthermore, the transport is modulated by different pH values and increasing concentrations of Pi, following the Michaelis-Menten kinetics (K0,5 = 0.08 mM Pi). PFA, monensin, furosemide and ouabain inhibited Pi transport, cell migration and adhesion. CONCLUSIONS: Taken together, these results showed that the uptake of Pi in MDA-MB-231 cells is modulated by sodium and by regulatory mechanisms of intracellular sodium gradient. General Significance: Pi transport might be regarded as a potential target for therapy against tumor progression.

Management challenges for best practices of the Kangaroo Method in the Neonatal ICU / Desafíos gerenciales para buenas prácticas del Método Madre-Canguro en la UTI Neonatal / Desafios gerenciais para boas práticas do Método Canguru na UTI Neonatal

ABSTRACT Objective: To understand the conditions that influence the adherence and application of best practices by nurses in the context of the Nursing care management in the Kangaroo Mother Care in the Neonatal ICU. Method: Study of qualitative approach, whose theoretical and methodological frameworks were Symbolic Interactionism and Grounded Theory, respectively. We used the in-depth interview with 8 nurses from the Neonatal ICU of a public maternity hospital in the city of Rio de Janeiro. Results: The conditions involved in adhering to the best practices of humanization in the Neonatal ICU are related mainly to human resources, interaction among professionals, work processes and leadership strategies; and care management. Conclusion: Professional and institutional challenges have been identified that need to be addressed to improve adherence and implementation of the Kangaroo Mother Care best practices.

RESUMEN Objetivo: Comprender las condiciones que influencian la adhesión y aplicación de buenas prácticas por enfermeros en el contexto de la gestión del cuidado de Enfermería del Método Madre-Canguro en la UTI Neonatal. Método: estudio de abordaje cualitativo, cuyos referenciales teórico y metodológico fueron el Interaccionismo Simbólico y la Teoría Fundamentada en Datos, respectivamente. Se utilizó la entrevista en profundidad con 8 enfermeros de la UTI Neonatal de una maternidad pública en la ciudad de Rio de Janeiro. Resultados: las condiciones intervinientes en la adhesión de las buenas prácticas de humanización en la UTI Neonatal están relacionadas principalmente con los recursos humanos, la interacción entre los profesionales, los procesos de trabajo y las estrategias de liderazgo y gestión del cuidado. Conclusión: Se plantearon desafíos de orden profesional e institucional que necesitan ser atendidos para mejorar la adhesión y aplicación de las buenas prácticas del Método Madre-Canguro.

RESUMO Objetivo: Compreender as condições que influenciam a adesão e aplicação de boas práticas por enfermeiros no contexto do gerenciamento do cuidado de Enfermagem no Método Canguru na UTI Neonatal. Método: estudo de abordagem qualitativa, cujos referenciais teórico e metodológico foram Interacionismo Simbólico e a Teoria Fundamentada nos Dados, respectivamente. Utilizou-se a entrevista em profundidade com 8 enfermeiros da UTI Neonatal de uma maternidade pública na cidade do Rio de Janeiro. Resultados: As condições intervenientes na adesão às boas práticas de humanização na UTI Neonatal estão relacionadas principalmente aos recursos humanos, interação entre os profissionais, processos de trabalho e estratégias de liderança; e gerenciamento do cuidado. Conclusão: Foram elencados desafios de ordem profissional e institucional que precisam ser atendidos para melhorar adesão e aplicação das boas práticas do Método Canguru.

Tumor-Derived Exosomes Induce the Formation of Neutrophil Extracellular Traps: Implications For The Establishment of Cancer-Associated Thrombosis.

Cancer patients are at an increased risk of developing thromboembolic complications. Several mechanisms have been proposed to explain cancer-associated thrombosis including the release of tumor-derived extracellular vesicles and the activation of host vascular cells. It was proposed that neutrophil extracellular traps (NETs) contribute to the prothrombotic phenotype in cancer. In this study, we evaluated the possible cooperation between tumor-derived exosomes and NETs in cancer-associated thrombosis. Female BALB/c mice were orthotopically injected with 4T1 breast cancer cells. The tumor-bearing animals exhibited increased levels of plasma DNA and myeloperoxidase in addition to significantly increased numbers of circulating neutrophils. Mice were subjected to either Rose Bengal/laser-induced venous thrombosis or ferric chloride-induced arterial thrombosis models. The tumor-bearing mice exhibited accelerated thrombus formation in both models compared to tumor-free animals. Treatment with recombinant human DNase 1 reversed the prothrombotic phenotype of tumor-bearing mice in both models. Remarkably, 4T1-derived exosomes induced NET formation in neutrophils from mice treated with granulocyte colony-stimulating factor (G-CSF). In addition, tumor-derived exosomes interacted with NETs under static conditions. Accordingly, the intravenous administration of 4T1-derived exosomes into G-CSF-treated mice significantly accelerated venous thrombosis in vivo. Taken together, our observations suggest that tumor-derived exosomes and neutrophils may act cooperatively in the establishment of cancer-associated thrombosis.

Salivary Thromboxane A2-Binding Proteins from Triatomine Vectors of Chagas Disease Inhibit Platelet-Mediated Neutrophil Extracellular Traps (NETs) Formation and Arterial Thrombosis.

BACKGROUND: The saliva of blood-feeding arthropods contains a notable diversity of molecules that target the hemostatic and immune systems of the host. Dipetalodipin and triplatin are triatomine salivary proteins that exhibit high affinity binding to prostanoids, such as TXA2, thus resulting in potent inhibitory effect on platelet aggregation in vitro. It was recently demonstrated that platelet-derived TXA2 mediates the formation of neutrophil extracellular traps (NETs), a newly recognized link between inflammation and thrombosis that promote thrombus growth and stability. METHODOLOGY/PRINCIPAL FINDINGS: This study evaluated the ability of dipetalodipin and triplatin to block NETs formation in vitro. We also investigated the in vivo antithrombotic activity of TXA2 binding proteins by employing two murine models of experimental thrombosis. Remarkably, we observed that both inhibitors abolished the platelet-mediated formation of NETs in vitro. Dipetalodipin and triplatin significantly increased carotid artery occlusion time in a FeCl3-induced injury model. Treatment with TXA2-binding proteins also protected mice from lethal pulmonary thromboembolism evoked by the intravenous injection of collagen and epinephrine. Effective antithrombotic doses of dipetalodipin and triplatin did not increase blood loss, which was estimated using the tail transection method. CONCLUSIONS/SIGNIFICANCE: Salivary TXA2-binding proteins, dipetalodipin and triplatin, are capable to prevent platelet-mediated NETs formation in vitro. This ability may contribute to the antithrombotic effects in vivo. Notably, both molecules inhibit arterial thrombosis without promoting excessive bleeding. Our results provide new insight into the antihemostatic effects of TXA2-binding proteins and may have important significance in elucidating the mechanisms of saliva to avoid host's hemostatic responses and innate immune system.

(99m)Tc-ixolaris targets glioblastoma-associated tissue factor: in vitro and pre-clinical applications.

BACKGROUND: The clotting initiator protein tissue factor (TF) has recently been described as a potential target that can be exploited to image aggressive tumors. Ixolaris is a specific TF inhibitor that blocks tumor cell procoagulant activity and tumor growth. OBJECTIVE: Herein we evaluated the ability of (99m)Tc-ixolaris to target tumor-derived TF using an orthotopic glioblastoma (GBM) model in mice. METHODS: The right forebrains of Swiss mice were stereotactically inoculated with U87-MG human GBM cells. Histological and immunohistochemical analyses were performed on the resulting tumors after 35-45 days. The biodistribution of (99m)Tc-ixolaris was evaluated by semi-quantitative whole-body scintigraphy and a quantitative analysis of radioactivity in isolated organs. RESULTS: No (99m)Tc-ixolaris uptake was observed in brain of tumor-free mice, independently of the integrity of brain-blood barrier. In contrast, the presence of TF-expressing brain tumor masses determined a significant (99m)Tc-ixolaris uptake. CONCLUSION: (99m)Tc-ixolaris recognized TF-expressing GBM cells in vivo. Given the proposed role of TF in tumor progression, (99m)Tc-ixolaris is a promising radiopharmaceutical agent for quantifying cancer-associated TF in aggressive tumors, including GBM.

Plasmodium falciparum infection induces expression of a mosquito salivary protein (Agaphelin) that targets neutrophil function and inhibits thrombosis without impairing hemostasis.

BACKGROUND: Invasion of mosquito salivary glands (SGs) by Plasmodium falciparum sporozoites is an essential step in the malaria life cycle. How infection modulates gene expression, and affects hematophagy remains unclear. PRINCIPAL FINDINGS: Using Affimetrix chip microarray, we found that at least 43 genes are differentially expressed in the glands of Plasmodium falciparum-infected Anopheles gambiae mosquitoes. Among the upregulated genes, one codes for Agaphelin, a 58-amino acid protein containing a single Kazal domain with a Leu in the P1 position. Agaphelin displays high homology to orthologs present in Aedes sp and Culex sp salivary glands, indicating an evolutionarily expanded family. Kinetics and surface plasmon resonance experiments determined that chemically synthesized Agaphelin behaves as a slow and tight inhibitor of neutrophil elastase (K(D) ∼ 10 nM), but does not affect other enzymes, nor promotes vasodilation, or exhibit antimicrobial activity. TAXIscan chamber assay revealed that Agaphelin inhibits neutrophil chemotaxis toward fMLP, affecting several parameter associated with cell migration. In addition, Agaphelin reduces paw edema formation and accumulation of tissue myeloperoxidase triggered by injection of carrageenan in mice. Agaphelin also blocks elastase/cathepsin-mediated platelet aggregation, abrogates elastase-mediated cleavage of tissue factor pathway inhibitor, and attenuates neutrophil-induced coagulation. Notably, Agaphelin inhibits neutrophil extracellular traps (NETs) formation and prevents FeCl3-induced arterial thrombosis, without impairing hemostasis. CONCLUSIONS: Blockade of neutrophil elastase emerges as a novel antihemostatic mechanism in hematophagy; it also supports the notion that neutrophils and the innate immune response are targets for antithrombotic therapy. In addition, Agaphelin is the first antihemostatic whose expression is induced by Plasmodium sp infection. These results suggest that an important interplay takes place in parasite-vector-host interactions.