Osteoprotegerin Is Essential for the Development of Endothelial Dysfunction Induced by Angiotensin II in Mice.

Opinions on the effects of osteoprotegerin (OPG) have evolved over the years from a protein protecting the vasculature from calcification to a cardiovascular risk factor contributing to inflammation within the vascular wall. Nowadays, the link between OPG and angiotensin II (Ang II) appears to be particularly important. In this study, the endothelial function was investigated in OPG-knockout mice (B6.129.S4-OPG, OPG-) and wild-type (C57BL/6J, OPG+) mice under basic conditions and after Ang II exposure by assessing the endothelium-dependent diastolic response of aortic rings to acetylcholine in vitro. A further aim of the study was to compare the effect of Ang II on the expression of cytokines in the aortic wall of both groups of mice. Our study shows that rings from OPG- mice had their normal endothelial function preserved after incubation with Ang II, whereas those from OPG+ mice showed significant endothelial dysfunction. We conclude that the absence of OPG, although associated with a pro-inflammatory cytokine profile in the vascular wall, simultaneously protects against Ang II-induced increases in pro-inflammatory cytokines in the murine vascular wall. Our study also demonstrates that the absence of OPG can result in a decrease in the concentration of pro-inflammatory cytokines in the vascular wall after Ang II exposure. The presence of OPG is therefore crucial for the development of Ang II-induced inflammation in the vascular wall and for the development of Ang II-induced endothelial dysfunction.

Direct Thrombin Inhibitor Dabigatran Compromises Pulmonary Endothelial Integrity in a Murine Model of Breast Cancer Metastasis to the Lungs; the Role of Platelets and Inflammation-Associated Haemostasis.

Activation of the coagulation cascade favours metastatic spread, but antithrombotic therapy might also have detrimental effects on cancer progression. In this study, we characterized the effects of dabigatran, a direct reversible thrombin inhibitor, on the pulmonary endothelial barrier and metastatic spread in a murine model of breast cancer metastasis. Dabigatran etexilate (100 mg kg-1) was administered to mice twice daily by oral gavage. Pulmonary metastasis, pulmonary endothelium permeability in vivo, and platelet reactivity were evaluated after intravenous injection of 4T1 breast cancer cells into BALB/c mice. The effect of dabigatran on platelet-dependent protection of pulmonary endothelial barrier in the presence of an inflammatory stimulus was also verified in vitro using human lung microvascular endothelial cell (HLMVEC) cultures. Dabigatran-treated mice harbored more metastases in their lungs and displayed increased pulmonary endothelium permeability after cancer cell injection. It was not associated with altered lung fibrin deposition, changes in INFγ, or complement activation. In the in vitro model of the pulmonary endothelial barrier, dabigatran inhibited platelet-mediated protection of pulmonary endothelium. In a murine model of breast cancer metastasis, dabigatran treatment promoted pulmonary metastasis by the inhibition of platelet-dependent protection of pulmonary endothelial barrier integrity.

Nitric oxide deficiency and endothelial-mesenchymal transition of pulmonary endothelium in the progression of 4T1 metastatic breast cancer in mice.

BACKGROUND: Mesenchymal transformation of pulmonary endothelial cells contributes to the formation of a metastatic microenvironment, but it is not known whether this precedes or follows early metastasis formation. In the present work, we characterize the development of nitric oxide (NO) deficiency and markers of endothelial-mesenchymal transition (EndMT) in the lung in relation to the progression of 4T1 metastatic breast cancer injected orthotopically in mice. METHODS: NO production, endothelial nitric oxide synthase (eNOS) phosphorylation status, markers of EndMT in the lung, pulmonary endothelium permeability, and platelet activation/reactivity were analyzed in relation to the progression of 4T1 breast cancer metastasis to the lung, as well as to lung tissue remodeling, 1-5 weeks after 4T1 cancer cell inoculation in Balb/c mice. RESULTS: Phosphorylation of eNOS and NO production in the lungs of 4T1 breast cancer-bearing mice was compromised prior to the development of pulmonary metastasis, and was associated with overexpression of Snail transcription factor in the pulmonary endothelium. These changes developed prior to the mesenchymal phenotypic switch in the lungs evidenced by a decrease in vascular endothelial-cadherin (VE-CAD) and CD31 expression, and the increase in pulmonary endothelial permeability, phenomena which coincided with early pulmonary metastasis. Increased activation of platelets was also detected prior to the early phase of metastasis and persisted to the late phase of metastasis, as evidenced by the higher percentage of unstimulated platelets binding fibrinogen without changes in von Willebrand factor and fibrinogen binding in response to ADP stimulation. CONCLUSIONS: Decreased eNOS activity and phosphorylation resulting in a low NO production state featuring pulmonary endothelial dysfunction was an early event in breast cancer pulmonary metastasis, preceding the onset of its phenotypic switch toward a mesenchymal phenotype (EndMT) evidenced by a decrease in VE-CAD and CD31 expression. The latter coincided with development of the first metastatic nodules in the lungs. These findings suggest that early endothelial dysfunction featured by NO deficiency rather than EndMT, might represent a primary regulatory target to prevent early pulmonary metastasis.

Dual antiplatelet therapy with clopidogrel and aspirin increases mortality in 4T1 metastatic breast cancer-bearing mice by inducing vascular mimicry in primary tumour.

Platelet inhibition has been considered an effective strategy for combating cancer metastasis and compromising disease malignancy although recent clinical data provided evidence that long-term platelet inhibition might increase incidence of cancer deaths in initially cancer-free patients. In the present study we demonstrated that dual anti-platelet therapy based on aspirin and clopidogrel (ASA+Cl), a routine regiment in cardiovascular patients, when given to cancer-bearing mice injected orthotopically with 4T1 breast cancer cells, promoted progression of the disease and reduced mice survival in association with induction of vascular mimicry (VM) in primary tumour. In contrast, treatment with ASA+Cl or platelet depletion did reduce pulmonary metastasis in mice, if 4T1 cells were injected intravenously. In conclusion, distinct platelet-dependent mechanisms inhibited by ASA+Cl treatment promoted cancer malignancy and VM in the presence of primary tumour and afforded protection against pulmonary metastasis in the absence of primary tumour. In view of our data, long-term inhibition of platelet function by dual anti-platelet therapy (ASA+Cl) might pose a hazard when applied to a patient with undiagnosed and untreated malignant cancer prone to undergo VM.

FT-IR- and Raman-based biochemical profiling of the early stage of pulmonary metastasis of breast cancer in mice.

The combination of FT-IR and Raman spectroscopies allowed the biochemical profiling of lungs in the early stage of pulmonary metastasis in the murine model of breast cancer. Histological staining was used as a reference. Raman spectroscopy was especially useful in the detection and semi-quantitative analysis of the vitamin A content in lung lipofibroblasts, whereas the IR technique provided semi-quantitative information on the contents of nucleic acids, carbohydrates including glycogen, and lipids as well as changes in the secondary structures of tissue proteins. Our spectroscopic results suggest that the early phase of metastasis in the lung is characterized by a decrease in the endogenous retinoid content in combination with a decrease in the content of glycogen and lipids.

Breast cancer pulmonary metastasis is increased in mice undertaking spontaneous physical training in the running wheel; a call for revising beneficial effects of exercise on cancer progression.

It has been repeatedly shown that regular aerobic exercise exerts beneficial effects on incidence and progression of cancer. However, the data regarding effects of exercise on metastatic dissemination remain conflicting. Therefore, in the present study the possible preventive effects of voluntary wheel running on primary tumor growth and metastases formation in the model of spontaneous pulmonary metastasis were analyzed after orthotopic injection of 4T1 breast cancer cells into mammary fat pads of female Balb/C mice. This study identified that in the mice injected with 4T1 breast cancer cells and running on the wheels (4T1 ex) the volume and size of the primary tumor were not affected, but the number of secondary nodules formed in the lungs was significantly increased compared to their sedentary counterparts (4T1 sed). This effect was associated with decreased NO production in the isolated aorta of exercising mice (4T1 ex), suggesting deterioration of endothelial function that was associated with lower platelet count without their overactivation. This was evidenced by comparable selectin P, active GPIIb/IIIa expression, fibrinogen and vWF binding on the platelet surface. In conclusion, voluntary wheel running appeared to impair, rather than improve endothelial function, and to promote, but not decrease metastasis in the murine orthotopic model of metastatic breast cancer. These results call for revising the notion of the persistent beneficial effects of voluntary exercise on breast cancer progression, though further studies are needed to elucidate mechanisms involved in pro-metastatic effects of voluntary exercise.

3D Raman imaging of systemic endothelial dysfunction in the murine model of metastatic breast cancer.

It was recently reported in the murine model of metastatic breast cancer (4T1) that tumor progression and development of metastasis is associated with systemic endothelial dysfunction characterized by impaired nitric oxide (NO) production. Using Raman 3D confocal imaging with the analysis of the individual layers of the vascular wall combined with AFM endothelial surface imaging, we demonstrated that metastasis-induced systemic endothelial dysfunction resulted in distinct chemical changes in the endothelium of the aorta. These changes, manifested as a significant increase in the protein content (18%) and a slight decrease in the lipid content (4%), were limited to the endothelium and did not occur in the deeper layers of the vascular wall. The altered lipid to protein ratio in the endothelium, although more pronounced in the fixed vascular wall, was also observed in the freshly isolated unfixed vascular wall samples in the aqueous environment (12 and 7% change of protein and lipid content, respectively). Our results support the finding that the metastasis induces systemic endothelial dysfunction that may contribute to cancer progression.

[Headaches in autoimmune diseases].

Vasculitides in autoimmune diseases are an important cause of secondary headaches. The article discusses the incidence of headache in primary and secondary vasculitides of the central nervous system. The symptoms of primary CNS vasculitis are presented. The occurrence of headache in large-vessel vasculitides, such as Takayasu arteritis and giant cell arteritis; medium-vessel vasculitides, such as polyarteritis nodosa and Kawasaki disease; and small-vessel vasculitides, such as microscopic polyangiitis, granulomatosis with polyangiitis, and eosinophilic granulomatosis with polyangiitis, are characterized. The occurrence of headache in vasculitides of different blood vessels, such as Behcet's disease and Cogan's syndrome, is presented as well. Systemic autoimmune diseases discussed in the paper are systemic lupus erythematosus, antiphospholipid antibody syndrome, rheumatoid arthritis, Sjogren's syndrome, and sarcoidosis. Vasculopathies which can mimic CNS vasculitides were discussed as well. Examples include reversible cerebral vasoconstriction, Susac's symdrome, and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

Comparative endothelial profiling of doxorubicin and daunorubicin in cultured endothelial cells.

Although anthracycline antibiotics have been successfully used for nearly half a century in the treatment of various malignancies, their use is limited by their cardiac and vascular toxicities, and the mechanisms of these toxicities are still not entirely clear. Herein, we comprehensively characterized cytotoxic effects of two structurally related anthracyclines, doxorubicin and daunorubicin. In nanomolar concentrations, both drugs induced DNA damage and increased nuclear area that were associated with their accumulation in the nucleus (doxorubicin ⩾50 nM and daunorubicin ⩾25 nM) as evidence by Raman microspectroscopy at 3820-4245 cm(-1). At low micromolar concentrations, doxorubicin (⩾5 µM) and daunorubicin (⩾1 µM) increased the generation of reactive oxygen species, decreased intracellular reduced glutathione, induced an alteration in endothelial elasticity and caused a reorganization of the F-actin cytoskeleton. In isolated mouse aortic rings, doxorubicin (⩾50 µM) was less potent than daunorubicin (⩾5 µM) in impairing the endothelium-dependent response. In summary, using a comprehensive endothelial profiling approach, we demonstrated clear-cut differences in the potencies to induce endotheliotoxic responses for two structurally similar chemotherapeutics, at a nuclear, cytosolic and membrane levels. Furthermore, our results suggest that the differences in the endothelial toxicities of doxorubicin and daunorubicin are linked to differences in their nuclear accumulation and the DNA damage-triggered response of the endothelium.