Overexpression of alternatively spliced tissue factor induces the pro-angiogenic properties of murine cardiomyocytic HL-1 cells

Tissue factor (coagulation factor III): a potential double-edge molecule to be targeted and re-targeted toward cancer

Tissue factor (TF) is a protein that plays a critical role in blood clotting, but recent research has also shown its involvement in cancer development and progression. Herein, we provide an overview of the structure of TF and its involvement in signaling pathways that promote cancer cell proliferation and survival, such as the PI3K/AKT and MAPK pathways. TF overexpression is associated with increased tumor aggressiveness and poor prognosis in various cancers. The review also explores TF's role in promoting cancer cell metastasis, angiogenesis, and venous thromboembolism (VTE). Of note, various TF-targeted therapies, including monoclonal antibodies, small molecule inhibitors, and immunotherapies have been developed, and preclinical and clinical studies demonstrating the efficacy of these therapies in various cancer types are now being evaluated. The potential for re-targeting TF toward cancer cells using TF-conjugated nanoparticles, which have shown promising results in preclinical studies is another intriguing approach in the path of cancer treatment. Although there are still many challenges, TF could possibly be a potential molecule to be used for further cancer therapy as some TF-targeted therapies like Seagen and Genmab's tisotumab vedotin have gained FDA approval for treatment of cervical cancer. Overall, based on the overviewed studies, this review article provides an in-depth overview of the crucial role that TF plays in cancer development and progression, and emphasizes the potential of TF-targeted and re-targeted therapies as potential approaches for the treatment of cancer.

Tmem63c is a potential pro-survival factor in angiotensin II-treated human podocytes

AIMS

Human podocytes (hPC) play an important role in the pathogenesis of renal diseases. In this context, angiotensin II (Ang II) and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) play a crucial role in podocyte injury. Recently, transmembrane protein (Tmem) 63c, a member of the Tmem-family was found to be expressed in kidney and associated with podocyte function. In this study, we analysed the expression regulation and functional impact of Tmem63c on cell viability and apoptosis in hPC in the context of Ang II activation.

MATERIALS AND METHODS

Expression of Tmem63c in response to Ang II and the NFκB inhibitor Bay 11-7082 was analysed by Real-Time PCR and Western blotting. Cellular functions were determined by functional assays.

KEY FINDINGS

We found Ang II to induce Tmem63c expression in hPC in a concentration-dependent manner. Inhibition of NFκB by Bay 11-7082 reduced basal as well as Ang II-induced Tmem63c expression. SiRNA-mediated down-regulation of Tmem63c diminished cell viability and protein kinase B (Akt) signaling and increased cell apoptosis of resting as well as Ang II-activated hPC.

SIGNIFICANCE

These data show that Ang II induced the expression of Tmem63c in hPC, possibly via NFκB-dependent mechanisms. Moreover, down-regulation of Tmem63c was associated with reduced cell viability, indicating Tmem63c to be a potential pro-survival factor in hPC.

Expression of flTF and asTF splice variants in various cell strains and tissues

Tissue factor (TF) expressed at the protein level includes two isoforms: The membrane-bound full-length TF (flTF) and the soluble alternatively spliced TF (asTF). flTF is the major thrombogenic form of TF, whereas asTF is more closely associated with tumor growth, angiogenesis, metastasis and cell growth. In order to further investigate the different expression and functions of TF splice variants, the expression of these two splice variants were detected in numerous cell strains and tissues in the present study. Quantitative polymerase chain reaction was used to measure the transcript levels of the TF variants in 11 human cell lines, including cervical cancer, breast cancer, hepatoblastoma, colorectal cancer and umbilical vein cells, and five types of tissue specimen, including placenta, esophageal cancer, breast cancer, cervical cancer (alongside normal cervical tissues) and non-small cell lung cancer (alongside adjacent and normal tissues). Furthermore, the effects of chenodeoxycholic acid (CDCA) and apolipoprotein M (apoM) on the two variants were investigated. The results demonstrated that flTF was the major form of TF, and the mRNA expression levels of flTF were higher than those of asTF in all specimens tested. CDCA significantly upregulated the mRNA expression levels of the two variants. Furthermore, overexpression of apoM promoted the expression levels of asTF in Caco-2 cells. The mRNA expression levels of asTF in cervical cancer tissues were significantly higher than in the corresponding normal tissues. To the best of our knowledge, the present study is the first to compare the expression of flTF and asTF in various samples. The results demonstrated that CDCA and apoM may modulate TF isoforms in different cell lines, and suggested that asTF may serve a role in the pathophysiological mechanism underlying cervical cancer development. In conclusion, the TF isoforms serve important and distinct roles in pathophysiological processes.

MicroRNA-19a contributes to the epigenetic regulation of tissue factor in diabetes

Background

Diabetes mellitus is characterized by chronic vascular disorder and presents a main risk factor for cardiovascular mortality. In particular, hyperglycaemia and inflammatory cytokines induce vascular circulating tissue factor (TF) that promotes pro-thrombotic conditions in diabetes. It has recently become evident that alterations of the post-transcriptional regulation of TF via specific microRNA(miR)s, such as miR-126, contribute to the pathogenesis of diabetes and its complications. The endothelial miR-19a is involved in vascular homeostasis and atheroprotection. However, its role in diabetes-related thrombogenicity is unknown. Understanding miR-networks regulating procoagulability in diabetes may help to develop new treatment options preventing vascular complications.

Methods and results

Plasma of 44 patients with known diabetes was assessed for the expression of miR-19a, TF protein, TF activity, and markers for vascular inflammation. High miR-19a expression was associated with reduced TF protein, TF-mediated procoagulability, and vascular inflammation based on expression of vascular adhesion molecule-1 and leukocyte count. We found plasma expression of miR-19a to strongly correlate with miR-126. miR-19a reduced the TF expression on mRNA and protein level in human microvascular endothelial cells (HMEC) as well as TF activity in human monocytes (THP-1), while anti-miR-19a increased the TF expression. Interestingly, miR-19a induced VCAM expression in HMEC. However, miR-19a and miR-126 co-transfection reduced total endothelial VCAM expression and exhibited additive inhibition of a luciferase reporter construct containing the F3 3′UTR.

Conclusions

While both miRs have differential functions on endothelial VCAM expression, miR-19a and miR-126 cooperate to exhibit anti-thrombotic properties via regulating vascular TF expression. Modulating the post-transcriptional control of TF in diabetes may provide a future anti-thrombotic and anti-inflammatory therapy.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0678-z) contains supplementary material, which is available to authorized users.

Tumor-Derived Tissue Factor Aberrantly Activates Complement and Facilitates Lung Tumor Progression via Recruitment of Myeloid-Derived Suppressor Cells

The initiator of extrinsic coagulation, tissue factor (TF), and its non-coagulant isoform alternatively spliced TF (asTF) are closely associated with tumor development. In the tumor microenvironment, the role of TF-induced coagulation in tumor progression remains to be fully elucidated. Using TF-knockdown lung tumor cells, we showed that TF is the dominant component of procoagulant activity but is dispensable in the cellular biology of tumor cells. In a xenograft model, using immunohistochemical analysis and flow cytometry analysis of the tumor microenvironment, we demonstrated that TF-induced fibrin deposition, which is correlated with complement activation and myeloid-derived suppressor cell (MDSC) recruitment, is positively associated with tumor progression. C5aR antagonism blunted the effect of TF on tumor progression and decreased MDSC recruitment. In conclusion, our data suggested that in tumor microenvironment, TF-induced coagulation activated the complement system and subsequently recruited myeloid-derived suppressor cells to promote tumor growth, which brings new insights into the coagulation-induced complement activation within the tumor microenvironment during tumor progression.

Regulation of podoplanin expression by microRNA-29b associates with its antiapoptotic effect in angiotensin II-induced injury of human podocytes

BACKGROUND

Angiotensin (Ang)II is involved in induction of proteinuria, renal injury, and apoptosis and thus a major contributor to the development of chronic kidney disease. Podocytes are of major importance for the pathogenesis of several kidney diseases. Decrease of podoplanin (PDPN) in podocytes and podocyte loss has been associated with the development of proteinuria. Little is known about the regulation and biological function of PDPN in podocytes and its role in AngII-mediated kidney damage. Here, we determined the influence of AngII on the expression of PDPN, microRNA (miRNA)-29b and miRNA-497 in human podocytes. Further, we analyzed the impact of small interfering RNA-mediated downregulation of PDPN on AngII-induced apoptosis and viability. Moreover, we characterized the role of miRNA-29b and miRNA-497 in expression regulation of PDPN.

METHODS

Cell viability and apoptosis were determined by functional assays. Expression analyses were done via Real-Time PCR and western blot analyses. Dual luciferase assay was performed to characterize miRNA-mediated expression control.

RESULTS

AngII increased the expression of miRNA-29b and reduced PDPN. Small interfering RNA-mediated downregulation of PDPN increased proapoptotic caspase-3 activation and cytochrome C translocation, whereas cell viability and Akt phosphorylation were reduced in AngII-stimulated podocytes. In contrast to miRNA-497, transfection of cells with miRNA-29b mimics significantly decreased PDPN. Cotransfection of cells with miRNA-29b and a dual luciferase reporter vector decreased the luciferase activity compared with controls.

CONCLUSION

These data demonstrate the posttranscriptional control of PDPN expression by miRNA-29b and support a role of PDPN as an antiapoptotic prosurvival factor in AngII-induced injury of human podocytes.

CCN1/CYR61-mediated meticulous patrolling by Ly6Clow monocytes fuels vascular inflammation

Inflammation is characterized by the recruitment of leukocytes from the bloodstream. The rapid arrival of neutrophils is followed by a wave of inflammatory lymphocyte antigen 6 complex (Ly6C)-positive monocytes. In contrast Ly6C(low) monocytes survey the endothelium in the steady state, but their role in inflammation is still unclear. Here, using confocal intravital microscopy, we show that upon Toll-like receptor 7/8 (TLR7/8)-mediated inflammation of mesenteric veins, platelet activation drives the rapid mobilization of Ly6C(low) monocytes to the luminal side of the endothelium. After repeatedly interacting with platelets, Ly6C(low) monocytes commit to a meticulous patrolling of the endothelial wall and orchestrate the subsequent arrival and extravasation of neutrophils through the production of proinflammatory cytokines and chemokines. At a molecular level, we show that cysteine-rich protein 61 (CYR61)/CYR61 connective tissue growth factor nephroblastoma overexpressed 1 (CCN1) protein is released by activated platelets and enables the recruitment of Ly6C(low) monocytes upon vascular inflammation. In addition endothelium-bound CCN1 sustains the adequate patrolling of Ly6C(low) monocytes both in the steady state and under inflammatory conditions. Blocking CCN1 or platelets with specific antibodies impaired the early arrival of Ly6C(low) monocytes and abolished the recruitment of neutrophils. These results refine the leukocyte recruitment cascade model by introducing endothelium-bound CCN1 as an inflammation mediator and by demonstrating a role for platelets and patrolling Ly6C(low) monocytes in acute vascular inflammation.

Risk of venous and arterial thromboembolic events associated with anti-VEGF agents in advanced non-small-cell lung cancer: a meta-analysis and systematic review

Aims

To assess the incidence and risk of arterial and venous thromboembolic events (ATEs and VTEs) associated with antivascular endothelial growth factor (VEGF) agents, including VEGF receptor-tyrosine kinase inhibitors and VEGF monoclonal antibodies, in advanced non-small-cell lung cancer (NSCLC) patients.

Methods

We performed a broad search of PubMed for relevant trials. Prospective randomized trials evaluating therapy with or without anti-VEGF agents in patients with advanced NSCLC were included for analysis. Data on VTEs and ATEs were extracted. The overall incidence, Peto odds ratio (Peto OR), and 95% confidence intervals (CIs) were pooled according to the heterogeneity of included trials.

Results

A total of 13,436 patients from 23 trials were included for analysis. Our results showed that anti-VEGF agents significantly increased the risk of developing high-grade ATEs (Peto OR: 1.44, 95% CI: 1.00–2.07, P=0.048), but not for all-grade ATEs (Peto OR: 0.94, 95% CI: 0.56–1.59, P=0.82) compared with controls. Additionally, no increased risk of all-grade and high-grade VTEs (Peto OR: 0.94, 95% CI: 0.67–1.31, P=0.71 and Peto OR: 0.95, 95% CI: 0.73–1.22, P=0.67, respectively) was observed in advanced NSCLC patients receiving anti-VEGF agents.

Conclusion

The use of anti-VEGF agents in advanced NSCLC patients significantly increased the risk of high-grade ATEs, but not for VTEs. Clinicians should be aware of the risk of severe ATEs with administration of these drugs in advanced NSCLC patients.

Tissue Factor: A Conventional or Alternative Target in Cancer Therapy

BACKGROUND

Tissue factor (TF) is an evolutionary conserved glycoprotein that plays an important role in the pathogenesis of cancer. TF is expressed in 2 naturally occurring protein isoforms, membrane-bound full-length (fl)TF and soluble alternatively spliced (as)TF. Both isoforms have been shown to affect a variety of pathophysiologically relevant functions, such as tumor-associated angiogenesis, thrombogenicity, tumor growth, and metastasis. Therefore, targeting TF either by direct inhibition or indirectly, i.e., on a posttranscriptional level, offers a novel therapeutic option for cancer treatment.

CONTENT

In this review we summarize the latest findings regarding the role of TF and its isoforms in cancer biology. Moreover, we briefly depict and discuss the therapeutic potential of direct and/or indirect inhibition of TF activity and expression for the treatment of cancer.

SUMMARY

asTF and flTF play important and often distinct roles in cancer biology, i.e., in thrombogenicity and angiogenesis, which is mediated by isoform-specific signal transduction pathways. Therefore, both TF isoforms and downstream signaling are promising novel therapeutic targets in malignant diseases.

Metformin modulates apoptosis and cell signaling of human podocytes under high glucose conditions

Diabetic nephropathy, which is associated with loss of human (h) podocytes (PC), is a major complication in diabetes mellitus. High-glucose modulates AMP-activated protein kinase (AMPK) signaling and cell apoptosis. Metformin has been demonstrated to reduce apoptosis and albuminuria in type 2 diabetes. Here, we examined the effect of metformin on cell apoptosis and on pro-/anti-apoptotic signaling in hPC. Expression analyses were done by real-time polymerase chain reaction and western blotting. Moreover, a functional apoptosis assay was performed in hPC. Determination of kinase activation by phosphorylation was done via immunodetection analyses and digital quantification. We found that hPC express organic cation transporter 1 which is the major uptake transporter of metformin. High-glucose reduced AMPK phosphorylation and induced mammalian target of rapamycin (mTOR) activation in podocytes, which was abolished and reversed by pre-treatment with metformin. Furthermore, metformin reduced high-glucose-induced podocytes apoptosis in a concentration-dependent manner. In summary, metformin exhibits an anti-apoptotic impact on podocytes under high-glucose conditions via activation of AMPK and inhibition of mTOR signaling. These data support a beneficial effect of metformin in diabetic nephropathy.

Tissue factor in tumor microenvironment: a systematic review

The aberrant hemostasis is a common manifestation of cancer, and venous thromboembolism (VTE) is the second leading cause of cancer patients’ mortality. Tissue factor (TF), comprising of a 47-kDa transmembrane protein that presents in subendothelial tissues and leukocytes and a soluble isoform, have distinct roles in the initiation of extrinsic coagulation cascade and thrombosis. Laboratory and clinical evidence showed the deviant expression of TF in several cancer systems and its tumor-promoting effects. TF contributes to myeloid cell recruitment in tumor stroma, thereby remodeling of tumor microenvironment. Additionally, the number of TF-positive-microparticles (TF⁺MP) from tumor origins correlates with the VTE rates in cancer patients. In this review, we summarize our current understanding of the TF regulation and roles in tumor progression and clinical complications.

The role of tissue factor isoforms in cancer biology

Tissue Factor (TF) is an evolutionary conserved glycoprotein, which is of immense importance for a variety of biologic processes. TF is expressed in two naturally occurring protein isoforms, membrane-bound "full-length" (fl)TF and soluble alternatively spliced (as)TF. The TF isoform expression is differentially modulated on post-transcriptional level via regulatory factors, such as serine/arginine-rich (SR) proteins, SR protein kinases and micro (mi)RNAs. Both isoforms mediate a variety of physiologic- and pathophysiologic-relevant functions, such as thrombogenicity, angiogenesis, cell signaling, tumor cell proliferation and metastasis. In this review, we will depict the main mechanisms regulating the TF isoform expression in cancer and under other pathophysiologic-relevant conditions. Moreover, we will summarize and discuss the latest findings regarding the role of TF and its isoforms in cancer biology.

Regulation of vascular function on posttranscriptional level

Posttranscriptional control of gene expression is crucial for regulating plurality of proteins and functional plasticity of the proteome under (patho)physiologic conditions. Alternative splicing as well as micro (mi)RNA-mediated mechanisms play an important role for the regulation of protein expression on posttranscriptional level. Both alternative splicing and miRNAs were shown to influence cardiovascular functions, such as endothelial thrombogenicity and the vascular tone, by regulating the expression of several vascular proteins and their isoforms, such as Tissue Factor (TF) or the endothelial nitric oxide synthase (eNOS). This review will summarize and discuss the latest findings on the (patho)physiologic role of alternative splicing processes as well as of miRNAs on modulation of vascular functions, such as coagulation, thrombosis, and regulation of the vascular tone.

The impact of microRNAs on the regulation of tissue factor biology

Tissue factor (TF) and its isoforms play an important role in a variety of physiologic and pathophysiologic functions, such as initiation of blood coagulation, vessel wall hemostasis, angiogenesis, and tumorigenesis. Micro(mi)RNAs are crucial for post-transcriptional control of protein generation by regulating the expression of one-third of all human genes. In recent years, miRNAs were shown to modulate the expression and biologic function of TF in different physiologic- and pathophysiologic-relevant settings, such as in autoimmune diseases and in different types of cancer. In the present review, we will summarize and discuss the latest findings regarding the impact of miRNAs on the generation of TF and its isoforms as well as on regulation of TF biology under normal and pathophysiologic conditions.

Nonproteolytic properties of murine alternatively spliced tissue factor: implications for integrin-mediated signaling in murine models

This study was performed to determine whether murine alternatively spliced tissue factor (masTF) acts analogously to human alternatively spliced tissue factor (hasTF) in promoting neovascularization via integrin ligation. Immunohistochemical evaluation of a spontaneous murine pancreatic ductal adenocarcinoma model revealed increased levels of masTF and murine full-length tissue factor (mflTF) in tumor lesions compared with benign pancreas; furthermore, masTF colocalized with mflTF in spontaneous aortic plaques of Ldlr(-/-) mice, indicating that masTF is likely involved in atherogenesis and tumorigenesis. Recombinant masTF was used to perform in vitro and ex vivo studies examining its integrin-mediated biologic activity. Murine endothelial cells (ECs) rapidly adhered to masTF in a β3-dependent fashion. Using adult and embryonic murine ECs, masTF potentiated cell migration in transwell assays. Scratch assays were performed using murine and primary human ECs; the effects of masTF and hasTF were comparable in murine ECs, but in human ECs, the effects of hasTF were more pronounced. In aortic sprouting assays, the potency of masTF-triggered vessel growth was undistinguishable from that observed with hasTF. The proangiogenic effects of masTF were found to be Ccl2-mediated, yet independent of vascular endothelial growth factor. In murine ECs, masTF and hasTF upregulated genes involved in inflammatory responses; murine and human ECs stimulated with masTF and hasTF exhibited increased interaction with murine monocytic cells under orbital shear. We propose that masTF is a functional homolog of hasTF, exerting some of its key effects via β3 integrins. Our findings have implications for the development of murine models to examine the interplay between blood coagulation, atherosclerosis and cancer.

Urotensin II stimulates vascular endothelial growth factor secretion from adventitial fibroblasts in synergy with angiotensin II

BACKGROUND

The adventitia plays an important role in and is considered to be the initiating site for vascular remodeling. Urotensin II (UII) and angiotensin II (Ang II) are the two most important vascular peptides involved in vascular remodeling in the adventitia. Nevertheless, little is known about their effect on the expression of vascular endothelial growth factor (VEGF). It was hypothesized that both UII and Ang II could induce VEGF expression in adventitial fibroblasts and VEGF may play a role in cell proliferation and collagen I synthesis induced by UII or Ang II.

METHODS AND RESULTS

Growth-arrested adventitial fibroblasts were incubated in serum-free medium with UII and/or Ang II and inhibitors of the mitogen-activated protein kinase (MAPK) pathway or VEGF-neutralizing antibodies. The VEGF expression was evaluated using enzyme-linked immunosorbent assay (ELISA), while the proliferation and collagen I synthesis were detected using methyl thiazol tetrazolium (MTT) assay and ELISA. It was found that: (1) both UII and Ang II could stimulate VEGF expression in adventitial fibroblasts and they had a synergistic effect; (2) MAPK pathway inhibitors could inhibit VEGF secretion induced by UII and/or Ang II; and (3) VEGF-neutralizing antibodies could inhibit UII/Ang II-induced cell proliferation and collagen synthesis in adventitial fibroblasts.

CONCLUSIONS

Induction of VEGF expression may be a new mechanism involved in vascular remodeling for UII and Ang II.

Alternatively spliced tissue factor and full-length tissue factor protect cardiomyocytes against TNF-α-induced apoptosis

Tissue Factor (TF) is expressed in various cell types of the heart, such as cardiomyocytes. In addition to its role in the initiation of blood coagulation, the TF:FVIIa complex protects cells from apoptosis. There are two isoforms of Tissue Factor (TF): "full length" (fl)TF--an integral membrane protein, and alternatively spliced (as)TF--a protein that lacks a transmembrane domain and can thus be secreted in a soluble form. Whether asTF or flTF affects apoptosis of cardiomyocytes is unknown. In this study, we examined whether asTF or flTF protects murine cardiomyocytes from TNF-α-induced apoptosis. We used murine cardiomyocytic HL-1 cells and primary murine embryonic cardiomyocytes that overexpressed either murine asTF or murine flTF, and stimulated them with TNF-α to initiate cell death. Apoptosis was assessed by annexin-V assay, propidium iodide assay, as well as activation of caspase-3 and -9. In addition, signaling via integrins, Akt, NFκB and Erk1/2, and gene-expression of Bcl-2 family members were analyzed. We here report that overexpression of asTF reduced phosphatidylserine exposure upon TNF-α-stimulation. asTF overexpression led to an increased expression and phosphorylation of Akt, as well as up-regulation of the anti-apoptotic protein Bcl-x(L). The anti-apoptotic effects of asTF overexpression were mediated via α(V)β(3)/Akt/NFκB signaling and were dependent on Bcl-x(L) expression in HL-1 cells. The anti-apoptotic activity of asTF was also observed using primary cardiomyocytes. Analogous yet less pronounced anti-apoptotic sequelae were observed due to overexpression of flTF. Importantly, cardiomyocytes deficient in TF exhibited increased apoptosis compared to wild type cells. We propose that asTF and flTF protect cardiomyocytes against TNF-α-induced apoptosis via activation of specific signaling pathways, and up-regulation of anti-apoptotic members of the Bcl-2 protein family.

Bivalirudin inhibits periprocedural platelet function and tissue factor expression of human smooth muscle cells

AIM

A major concern of stent implantation after percutaneous coronary intervention (PCI) is acute stent thrombosis. Effective inhibition of periprocedural platelet function in patients with coronary artery disease (CAD) leads to an improved outcome. In this study, we examined the periprocedural platelet reactivity after administrating bivalirudin during PCI compared to unfractionated heparin (UFH) administration. Further, the effect of bivalirudin on induced tissue factor (TF) expression in smooth muscle cells (SMC) was determined.

METHODS

Patients with CAD (n = 58) and double antithrombotic medication were treated intraprocedural with UFH (n = 30) or bivalirudin (n = 28). Platelet activation markers were flow cytometrically measured before and after stenting. The expression of TF in SMC was determined by real-time PCR and Western blotting. The thrombogenicity of platelet-derived microparticles and SMC was assessed via a TF activity assay.

RESULTS

Bivalirudin significantly diminished the agonist-induced platelet reactivity post-PCI. Compared to UFH treatment, the adenosine diphosphate (ADP) and thrombin receptor-activating peptide (TRAP)-induced thrombospondin expression post-PCI was reduced when bivalirudin was administrated during intervention. In contrast to UFH, bivalirudin reduced the P-selectin expression of unstimulated and ADP-induced platelets post-PCI. Moreover, bivalirudin inhibited the thrombin-, but not FVIIa- or FVIIa/FX-induced TF expression and pro-coagulant TF activity of SMC. Moreover, bivalirudin reduced the TF activity of platelet-derived microparticles postinduction with TRAP or ADP.

CONCLUSIONS

Bivalirudin is better than UFH in reducing periprocedural platelet activation. Moreover, thrombin-induced TF expression is inhibited by bivalirudin. Thus, bivalirudin seems to be a better anticoagulant during PCI than UFH.

Tissue Factor Regulates Microvessel Formation and Stabilization by Induction of Chemokine (C-C motif) Ligand 2 Expression

Objective—

Tissue factor (TF) triggers arterial thrombosis. TF is also able to initiate cellular signaling mechanisms leading to angiogenesis. Because high cardiovascular risk atherosclerotic plaques show significant angiogenesis, our objective was to investigate whether TF is able to trigger and stabilize atherosclerotic plaque neovessel formation.

Methods and Results—

In this study, we showed, by real-time confocal microscopy in 3-dimensional basement membrane cocultures, that TF in human microvascular endothelial cells (HMEC-1) and in human vascular smooth muscle cells (HVSMCs) plays an important role in the formation of capillary-like networks. TF silencing in endothelial cells and smooth muscle cells inhibits the formation of tube-like structures with stable phenotype. Using an in vivo model, we observed that TF inhibition in either HMEC-1 or HVSMCs reduced their shared ability to form new capillaries. The phenotypic changes induced by TF silencing were linked to reduced chemokine (C-C motif) ligand 2 (CCL2) expression in endothelial cells. Wound healing and chemotactic assays demonstrated that TF-induced release of CCL2 stimulated HVSMC migration to HMEC-1.

Conclusion—

Endogenous TF regulates CCL2 production in endothelial cells. Secreted CCL2 mediates the angiogenic effect of TF by recruiting smooth muscle cells toward endothelial cells and facilitates the maturation of newly formed microvessels.