Ir-CPI, a coagulation contact phase inhibitor from the tick Ixodes ricinus, inhibits thrombus formation without impairing hemostasis

Blood coagulation starts immediately after damage to the vascular endothelium. This system is essential for minimizing blood loss from an injured blood vessel but also contributes to vascular thrombosis. Although it has long been thought that the intrinsic coagulation pathway is not important for clotting in vivo, recent data obtained with genetically altered mice indicate that contact phase proteins seem to be essential for thrombus formation. We show that recombinant Ixodes ricinus contact phase inhibitor (Ir-CPI), a Kunitz-type protein expressed by the salivary glands of the tick Ixodes ricinus, specifically interacts with activated human contact phase factors (FXIIa, FXIa, and kallikrein) and prolongs the activated partial thromboplastin time (aPTT) in vitro. The effects of Ir-CPI were also examined in vivo using both venous and arterial thrombosis models. Intravenous administration of Ir-CPI in rats and mice caused a dose-dependent reduction in venous thrombus formation and revealed a defect in the formation of arterial occlusive thrombi. Moreover, mice injected with Ir-CPI are protected against collagen- and epinephrine-induced thromboembolism. Remarkably, the effective antithrombotic dose of Ir-CPI did not promote bleeding or impair blood coagulation parameters. To conclude, our results show that a contact phase inhibitor is an effective and safe antithrombotic agent in vivo

Caveolae, caveolin and control of vascular tone: nitric oxide (NO) and endothelium derived hyperpolarizing factor (EDHF) regulation.

Endothelium plays a crucial role in the regulation of cardiovascular homeostasis through the release of vasoactive factors. Nitric oxide (NO) and endothelium-derived hyperpolarizing factors (EDHF) are the two major actors controlling the vasomotor tone. The endothelial nitric oxide synthase (eNOS) was reported in the mid 90ies to be under the control of caveolin, the structural protein of caveolae. Nowadays, a large body of evidence has confirmed that the caveolin/eNOS interaction was needed to prevent inadequate NO production under basal conditions but also to facilitate the integration of extracellular stimuli to intracellular NO signals. Compartmentation of key actors in the EDHF signaling pathway is now also proposed to take place into caveolae. Accordingly, caveolin-deficient animals revealed both an unopposed NO production promoting vessel dilation and a lack of EDHF-driven vasorelaxation. The transient receptor potential (TRP) channels are the link between caveolae and EDHF. Different TRP channels involved in the capacitative calcium entry were found to directly interact with caveolin-1 in endothelial cells. TRPC1 and TRPC4 form a complex with the endoplasmic reticulum IP3 receptor thereby optimizing calcium signaling. EDHF-driven vasodilation was documented to be altered in a TRPV4-deficient mouse model. The close vicinity between TRPV4 and SKCa channels in caveolae together with the gap-junctions subunits connexins support a role of these microdomains in the generation and propagation of EDHF to vascular smooth muscle cells. In conclusion, caveolae and caveolin are important control points in the control of blood pressure by the endothelium. This also highlights how any alteration in the caveolae integrity or caveolin abundance may lead to and/or exacerbate endothelial dysfunction and associated cardiovascular diseases

Rôle anti-apoptotique de la TSP-1 dans les cellules thyroïdiennes normales et cancéreuses ( Implication de la voie des sphingolipides)

REIMS-BU Santé (514542104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Vasodilatory mechanisms of beta receptor blockade.

Beta-blockers are widely prescribed for the treatment of a variety of cardiovascular pathologies. Compared to traditional beta-adrenergic antagonists, beta-blockers of the new generation exhibit ancillary properties such as vasodilation through different mechanisms. This translates into a more favorable hemodynamic profile. The relative affinities of beta-adrenoreceptor antagonists towards the three beta-adrenoreceptor isotypes matter for predicting their functional impact on vasomotor control. This review will focus on the mechanisms underlying beta-blocker-evoked vasorelaxation with a specific emphasis on agonist properties of beta(3)-adrenergic receptors

Rôle anti-apoptotique de la TSP-1 dans les cellules thyroïdiennes normales et cancéreuses ( Implication de la voie des sphingolipides)

REIMS-BU Santé (514542104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Hyaluronidase 1 deficiency preserves endothelial function and glycocalyx integrity in early streptozotocin-induced diabetes

Hyaluronic acid (HA) is a major component of the glycocalyx involved in vascular wall and endothelial glomerular permeability barrier. Endocytosed hyaluronidase HYAL1 is known to degrade HA into small fragments in different cell types including endothelial cells. In diabetes, the size and permeability of the glycocalyx are altered. In addition, type 1 diabetic patients present increased plasma levels of both HA and HYAL1.To investigate the potential implication of HYAL1 in the development of diabetes-induced endothelium dysfunction, we measured endothelial markers, endothelium-dependent vasodilation, arteriolar glycocalyx size, and glomerular barrier properties in wild-type and HYAL1 knockout (KO) mice with or without streptozotocin-induced diabetes. We observed that, 4 weeks after streptozotocin injections, the lack of HYAL1: 1) prevents diabetes-induced increases in soluble P-selectin concentrations and limits the impact of the disease on endothelium-dependent hyperpolarization (EDH)-mediated vasorelaxation; 2) increases glycocalyx thickness and maintains glycocalyx structure and HA content during diabetes; 3) prevents diabetes-induced glomerular barrier dysfunction assessed using urinary albumin/creatinine ratio and urinary 70/40-kDa dextran ratio. Our findings suggest that HYAL1 contributes to endothelial and glycocalyx dysfunction induced by diabetes. HYAL1 inhibitors could be explored as a new therapeutic approach to prevent vascular complications in diabetes

The acidic tumor microenvironment promotes the reconversion of nitrite into nitric oxide: towards a new and safe radiosensitizing strategy

PURPOSE: The biological status of nitrite recently evolved from an inactive end product of nitric oxide catabolism to the largest intravascular and tissue storage of nitric oxide (NO). Although low partial O(2) pressure favors enzymatic reconversion of nitrite into NO, low pH supports a nonenzymatic pathway. Because hypoxia and acidity are characteristics of the tumor microenvironment, we examined whether nitrite injection could preferentially lead to NO production in tumors and influence response to treatments. EXPERIMENTAL DESIGN: The effects of nitrite were evaluated on arteriole vasorelaxation, tumor cell respiration and tumor blood flow, oxygenation, and response to radiotherapy. RESULTS: We first showed that a small drop in pH (-0.6 pH unit) favored the production of bioactive NO from nitrite by documenting a higher cyclic guanosine 3',5'-monophosphate-dependent arteriole vasorelaxation. We then documented that an i.v. bolus injection of nitrite to tumor-bearing mice led to a transient increase in partial O(2) pressure in tumor but not in healthy tissues. Blood flow measurements failed to reveal an effect of nitrite on tumor perfusion, but we found that O(2) consumption by nitrite-exposed tumor cells was decreased at acidic pH. Finally, we showed that low dose of nitrite could sensitize tumors to radiotherapy, leading to a significant growth delay and an increase in mouse survival (versus irradiation alone). CONCLUSIONS: This study identified low pH condition (encountered in many tumors) as an exquisite environment that favors tumor-selective production of NO in response to nitrite systemic injection. This work opens new perspectives for the use of nitrite as a safe and clinically applicable radiosensitizing modality

Thrombospondin-1 C-terminal-derived peptide protects thyroid cells from ceramide-induced apoptosis through the adenylyl cyclase pathway.

Thrombospondin-1, a multi-modular matrix protein is able to interact with a variety of matrix proteins and cell-surface receptors. Thus it is multifunctional. In this work, we examined the role of thrombospondin-1 in ceramide-induced thyroid apoptosis. We focused on the VVM containing sequence localized in the C-terminal domain of the molecule. Primary cultured thyroid cells synthesize thrombospondin-1 depending on their morphological organization. As it leads thyrocytes to organize into monolayers before inducing apoptosis ceramide can modulate this organization. Here, we established that C(2)-ceramide treatment decreased thrombospondin-1 expression by interfering with the adenylyl cyclase pathway, thus leading to apoptosis. Furthermore, we demonstrated that the thrombospondin-1-derived peptide 4N1 (RFYVVMWK) abolished ceramide-induced thyroid cell death by preventing intracellular cAMP levels from dropping. Finally, we reported that 4N1-mediated inhibition of ceramide-induced apoptosis was consistently associated with a down-regulation of the caspase-3 processing. Integrin-associated protein receptor (IAP or CD47) was identified as a molecular relay mediating the observed 4N1 effects. Taken together, our results shed light for the first time on anti-apoptotic activities of the thrombospondin-1-derived peptide 4N1 and provide new information on how thrombospondin-1 may control apoptosis of non-tumoral cells

Delivery of Soluble VEGF Receptor 1 (sFlt1) by Gene Electrotransfer as a New Antiangiogenic Cancer Therapy.

Since tumor growth is highly dependent on the formation of new blood vessels, angiogenesis inhibitors have become important players in anticancer treatments. Although less cytotoxic than conventional chemotherapy, most of the available antiangiogenic agents may provoke severe adverse effects which can limit their use. The design of new antiangiogenic strategies therefore requires integrating an early evaluation of possible interference with quiescent endothelial cells and nontumor angiogenesis. Here, we describe such a novel antiangiogenic approach based on the in vivo delivery by gene electrotransfer of a negative regulator of angiogenesis, namely, sFlt1. We found that this soluble variant of the vascular endothelial growth factor receptor 1 (Flt1, also known as VEGFR1), which acts as a VEGF trap, differentially influences tumor and postischemic hind limb angiogenesis in mice. sFlt1 gene electrotransfer in tibial cranial muscle leads to high sFlt1 protein expression and secretion, leading to a significant delay in the growth of syngeneic tumors but not altering the revascularization of ischemic peripheral tissue. The higher sensitivity of tumor-bearing animals toward sFlt1 trapping effects (vs ischemia-recovering animals) might be explained by a distinct pattern of VEGF release, as shown by VEGF measurements in plasma and tissue. In conclusion, our data support sFlt1 gene electrotransfer as a novel and safe modality to target VEGF-driven tumor angiogenesis and to maintain unaltered the recovery potential of ischemic tissues

Effects of BM-573 on Endothelial Dependent Relaxation and Increased Blood Pressure at Early Stages of Atherosclerosis.

Endothelial dysfunction is considered to be an early event in atherosclerosis and plays a pivotal role in the development, progression and clinical complications of atherosclerosis. Previous studies have shown the beneficial effects of combined inhibition of thromboxane synthase and antagonism of thromboxane receptors by BM-573 on atherosclerosis; however our knowledge about the beneficial effects of BM-573 on endothelial function and increased blood pressure related to early stage of atherosclerosis is limited. In the present study, we investigated the effects of short-term (3μM, 1 hour) and chronic (10mg/L, 8 weeks) treatments with BM-573 on vasodilatory function, nitric oxide (NO) bioavailability, oxidative stress and systolic blood pressure in 15 weeks old apolipoprotein E-deficient (ApoE-KO) mice. ApoE-KO mice showed a reduced endothelium-derived relaxation. In addition, NO bioavailability was reduced and oxidative stress and blood pressure were increased in ApoE-KO mice versus wild-type mice. BM-573 treatments were able to improve the relaxation profile in ApoE-KO mice. Short-term effects of BM-573 were mainly mediated by an increased phosphorylation of both eNOS and Akt, whereas BM-573 in vivo treatment also reduced oxidative stress and restored NO bioavailability. In addition, chronic administration of BM-573 reduced systolic blood pressure in ApoE-KO mice. In conclusion, pharmacological modulation of TxA2 biosynthesis and biological activities by dual TP antagonism/TxAS inhibition with BM-573, already known to prevent plaque formation, has the potential to correct vasodilatory dysfunction at the early stages of atherosclerosis