Tissue Factor mRNA Levels Research Articles

Activated factor X stimulates atrial endothelial cells and tissues to promote remodelling responses through AT1R/NADPH oxidases/SGLT1/2.

Atrial fibrillation (AF), the most common cardiac arrhythmia favouring ischemic stroke and heart failure involves left atrial remodelling, fibrosis and a complex interplay between cardiovascular risk factors. This study examined whether activated factor X (FXa) induces pro-remodelling and pro-fibrotic responses in atrial endothelial cells (AECs) and human atrial tissues and determined the underlying mechanisms. AECs collected from porcine hearts and human right atrial appendages (RAA) from patients undergoing heart surgery. Protein expression levels were assessed by Western blot and immunofluorescence staining, mRNA levels by RT-qPCR, formation of reactive oxygen species (ROS) and NO using fluorescent probes, thrombin and angiotensin II generation by specific assays, fibrosis by Sirius red staining and senescence by senescence-associated beta-galactosidase (SA-β-gal) activity. In AECs, FXa increased ROS formation, senescence (SA-β-gal activity, p53, p21), angiotensin II generation and the expression of pro-inflammatory (VCAM-1, MCP-1), pro-thrombotic (tissue factor), pro-fibrotic (TGF-β and collagen-1/3a) and pro-remodelling (MMP-2/9) markers whereas eNOS levels and NO formation were reduced. These effects were prevented by inhibitors of FXa but not thrombin, protease-activated receptors antagonists (PAR-1/2) and inhibitors of NADPH oxidases, ACE, AT1R, SGLT1/SGLT2. FXa also increased expression levels of ACE1, AT1R, SGLT1/2 proteins which were prevented by SGLT1/2 inhibitors. Human RAA showed tissue factor mRNA levels that correlated with markers of endothelial activation, pro-remodelling and pro-fibrotic responses and SGLT1/2 mRNA levels. They also showed protein expression levels of ACE1, AT1R, p22phox, SGLT1/2, and immunofluorescence signals of nitrotyrosine and SGLT1/2 colocalized with those of CD31. FXa increased oxidative stress levels which were prevented by inhibitors of the AT1R/NADPH oxidases/SGLT1/2 pathway. FXa promotes oxidative stress triggering premature endothelial senescence and dysfunction associated with pro-thrombotic, pro-remodelling and pro-fibrotic responses in AECs and human RAA involving the AT1R/NADPH oxidases/SGLT1/2 pro-oxidant pathway. Targeting this pathway may be of interest to prevent atrial remodelling and the progression of atrial fibrillation substrate.

Tissue factor pathway-related biomarkers in liver cancer: activated factor VII–antithrombin complex and tissue factor mRNA levels are associated with mortality

BackgroundTissue factor (TF), the main initiator of the coagulation cascade, plays a role in cancer progression and prognosis. Activated factor VII–antithrombin complex (FVIIa-AT) is considered an indirect marker of TF exposure by reflecting TF-FVIIa interaction. ObjectivesTo assess the link between FVIIa-AT plasma levels, TF messenger RNA (mRNA) expression, and survival in cancer. MethodsTF pathway–related coagulation biomarkers were assessed in 136 patients with cancer (52 with hepatocellular carcinoma, 41 with cholangiocarcinoma, and 43 with colon cancer) undergoing surgical intervention with curative intent. TF mRNA expression analysis in neoplastic vs nonneoplastic liver tissues was evaluated in a subgroup of 91 patients with primary liver cancer. ResultsFVIIa-AT levels were higher in patients with cancer than in 136 sex- and age-matched cancer-free controls. In patients with cancer, high levels of FVIIa-AT and total TF pathway inhibitor were associated with an increased mortality risk after adjustment for confounders, but only FVIIa-AT remained a predictor of mortality by including both FVIIa-AT and total TF pathway inhibitor in Cox regression (hazard ratio, 2.80; 95% CI, 1.23-6.39; the highest vs the lowest quartile). This association remained significant even after adjustment for extracellular vesicle–associated TF-dependent procoagulant activity. In the subgroup of patients with primary liver cancer, patients with high TF mRNA levels had an increased mortality risk compared with that for those with low TF mRNA levels (hazard ratio, 1.92; 95% CI, 1.03-3.57), and there was a consistent correlation among high FVIIa-AT levels, high TF mRNA levels, and increased risk of mortality. ConclusionHigh FVIIa-AT levels may allow the identification of patients with cancer involving high TF expression and predict a higher mortality risk in liver cancer.

Comparison of the Therapeutic Effects of Adipose- and Bone Marrow-Derived Mesenchymal Stem Cells on Renal Fibrosis

Mesenchymal stem cells (MSCs) have attracted a great deal of interest as a therapeutic tool for renal fibrosis. Although both adipose-derived and bone marrow-derived MSCs (ADSCs and BMSCs, respectively) suppress renal fibrosis, which of these two has a stronger therapeutic effect remains unclear. This study aimed to compare the antifibrotic effects of ADSCs and BMSCs extracted from adipose tissue and bone marrow derived from the same rats. When cultured in serum-containing medium, ADSCs had a more potent inhibitory effect than BMSCs on renal fibrosis induced by ischemia-reperfusion injury in rats. ADSCs and BMSCs cultured in serum-free medium were equally effective in suppressing renal fibrosis. Mice infused with ADSCs (serum-containing or serum-free cultivation) had a higher death rate from pulmonary embolism than those infused with BMSCs. In vitro, mRNA levels of tissue factor, tumor necrosis factor-α-induced protein 6 and prostaglandin E synthase were higher in ADSCs than in BMSCs, while that of vascular endothelial growth factor was higher in BMSCs than in ADSCs. Although ADSCs had a stronger antifibrotic effect, these findings support the consideration of thromboembolism risk in clinical applications. Our results emphasize the importance of deciding between ADSCs and BMSCs based upon the target disease and culture method.

SOCS3 limits TNF and endotoxin-induced endothelial dysfunction by blocking a required autocrine interleukin-6 signal in human endothelial cells.

Increased circulating levels of soluble interleukin (IL)-6 receptor α (sIL-6Rα) are commonly observed during inflammatory responses, allowing for IL-6 signaling in cells that express the ubiquitous receptor subunit gp130 but not IL-6Rα, such as endothelial cells. Activation of Toll-like receptor (TLR)-4 or the tumor necrosis factor (TNF) receptor leads to NF-κB-dependent increases in endothelial IL-6 expression. Thus, we hypothesize that danger signals may induce autocrine IL-6 signaling within the endothelium via sIL-6Rα-mediated trans-signaling. In support of this hypothesis, we recently demonstrated that conditional deletion in the endothelium of the IL-6 signaling inhibitor SOCS3 leads to rapid mortality in mice challenged with the TLR-4 agonist endotoxin through increases in vascular leakage, thrombosis, leukocyte adhesion, and a type I-like interferon response. Here, we sought to directly test a role for sIL-6Rα in LPS-treated human umbilical vein and dermal blood microvascular endothelial cells. We show that cotreatment with sIL-6Rα dramatically increases the loss of barrier function and the expression of COX2 and tissue factor mRNA levels induced by LPS. This cotreatment led to strong activation of STAT1 and STAT3 while not affecting LPS-induced activation of p38 and NF-κB signaling. Similar results were obtained when sIL-6Rα was added to a TNF challenge. JAK inhibition by pretreatment with ruxolitinib or by SOCS3 overexpression blunted LPS and sIL-6R synergistic effects, whereas SOCS3 knockdown further increased the response. Together, these findings demonstrate that IL-6 signaling downstream of NF-κB activation leads to a strong endothelial activation and may explain the acute endotheliopathy observed during critical illness.

Expression and role of interleukin-1β and associated biomarkers in deep vein thrombosis.

Lower extremity deep vein thrombosis (DVT) is a common peripheral vascular disease, in which inflammation plays an important role. The aim of the present study was to investigate the expression and role of inflammatory factors in DVT. A rat model of venous thrombosis of the lower extremities was established through venous ligation surgery. The rats were examined at 2, 8, 24, 48 and 72 h after the induction of inferior venous stenosis and compared with control and sham surgery groups. The serum levels of interleukin-1β (IL-1β), tissue factor (TF) and xanthine oxidase (XOD) were measured using ELISAs. The morphology of the DVT tissue was observed by hematoxylin and eosin staining. Circulating endothelial cells (CECs) in peripheral blood were counted by flow cytometry. Reverse transcription-quantitative PCR and western blotting were used to detect mRNA and protein expression, respectively. The serum levels of IL-1β, TF and XOD exhibited no significant differences between the control and sham surgery groups. However, those in the rat model of DVT presented an upward trend from 2 to 24 h and peaked at 24 h, with a significant difference from the respective levels in the control and sham surgery groups. The histopathological analysis revealed the presence of red and mixed thrombi in the rats 2-48 h following the induction of inferior venous stenosis group with inflammatory cell infiltration in the vascular wall. Thrombus formation was evident after 72 h. While significant difference was observed in the number of CECs in the peripheral blood between the control and sham surgery groups, the number of peripheral blood CECs in the rats with inferior venous stenosis group increased from 8 to 72 h, with significant differences among these groups. The mRNA levels of IL-1β, TF, XOD and NF-κB in the tissues peaked at 24 h, with significant differences compared with those in the control and sham surgery groups. In addition, the protein expression level of NF-κB increased from 2 to 72 h. In conclusion, these results suggest that the high expression of IL-1β, TF, XOD and NF-κB may promote thrombus formation.

Prospective Evaluation of Thrombo-Hemorrhagic Events and Hypercoagulation Markers in Patients with Acute Promyelocytic Leukemia (APL) Receiving All-Trans Retinoic Acid (ATRA) Plus Chemotherapy

Introduction: Patients with APL typically present with a life-threatening thrombo-hemorrhagic syndrome (THS), due to the consumption of coagulation factors and platelets, secondary to clotting activation. Presently, all- trans retinoic acid (ATRA) has greatly improved the management of APL, but has not significantly changed the rate of early hemorrhagic deaths and may actually promote thrombosis.Characterizing the coagulopathy and identifying predictive markers of bleeding/clotting complications remain critical issues. Aim: In newly diagnosed APL patients, in the first month after diagnosis, we wanted prospectively to: 1. register thrombo/hemorrhagic events; 2. evaluate, the profiles of circulating hypercoagulation markers and the molecular expression of Tissue Factor (TF), before and during ATRA therapy; and 3. verify whether changes in the biomarker profiles correlate with the occurrence of thrombo-hemorragic events. Methods: Sixty consecutive APL patients receiving ATRA+Idarubicin for remission induction (GIMEMA protocol AIDA2000) were enrolled from January 2005 to March 2017. Blood samples from a subgroup of 30 patients (F/M= 11/19) were obtained at the onset (T0), and on days 7, 14 and 28 (T7, T14, T28) of remission induction therapy. Plasma levels of activated factor VII-antithrombin complex (FVIIa-AT), thrombin-antithrombin complex (TAT), and D-dimer were measured by ELISA; TF mRNA levels in peripheral blood mononuclear cells (PBMC) was evaluated in 16 APL patients by real time-polymerase chain reaction. Results: At enrolment (T0), before starting ATRA, 13.3% of APL patients presented with early major hemorrhages, including 3 (5%) fatal intracranial bleeding and 5 (8.3%) non-fatal major bleeding (i.e. gengivorrhagia, gastrointestinal bleeding, epistaxis, menorrhagia). At T0, the prevalence of thrombosis in the total group of 60 APL patients was 6.6%, including 1 fatal pulmonary embolism (PE), 2 non-fatal venous thrombosis (1 PE, 1 lower limb deep vein thrombosis [DVT]), and 1 non-fatal arterial thrombosis (acute myocardial infarction [AMI]). During ATRA therapy, 8.3% of APL patients developed major bleeding: including 2 fatal intracranial hemorrhage after 3 days of ATRA treatment and 3 non-fatal major bleeding (i.e. gengivorrhagia, epistaxis, menorrhagia) after 7, 10 and 17 days of ATRA. Two more patients developed non-fatal thrombosis (i.e. 1 AMI and 1 DVT) after 9 and 20 days of ATRA treatment, respectively. The laboratory sub-study of 30 subjects showed that, at T0, before starting therapy, the plasma levels of FVIIa-AT, TAT and D-dimer were significantly higher in APL patients compared to controls (p<0.05). During induction therapy with ATRA, the levels of TAT and D-dimer significantly (p<0.05) and progressively decreased at T7 and T14, reaching the lowest value at 28 days. Differently, FVIIa-AT levels were unchanged at T7 and T14, and dropped significantly only at T28 (p<0.05 vs T0). In addition, in APL PBMC from 16 patients, the levels of TF mRNA, initially elevated compared to healthy control PBMC (p<0.05), during induction therapy were significantly decreased by 68% and 90%, at T7 and T28, respectively. In these 16 APL patients, a statistically significant correlation (p<0.05) was found between decrease in TF mRNA and FVIIa-AT levels during ATRA therapy. Of the 30 patients included in the laboratory sub-study, 3 had non-fatal thrombosis at diagnosis, no major hemorrhages were recorded. The predictive value of THS of thrombotic markers could not be calculated. Conclusions: Our data show a significant rate (31%) of severe (fatal and non-fatal) thrombo/hemorrhagic events in our cohort of APL patients in the first 3 weeks of diagnosis, with 4 fatal events (6.6%) occurring early, before starting ATRA. Laboratory data show for the first time that, while TAT and D-dimer confirm to be sensitive to ATRA downregulation, differently FVIIa-AT levels persist at high level over time, showing the perseverance of TF-dependent clotting activation. Future large prospective clinical trials should include FVIIa-AT to evaluate persistent clotting activation during ATRA. DisclosuresFalanga:Advisory Board: Bayer, Janssen Speakers' bureau: Rovi, BMS: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rambaldi:Novartis, Roche/Genentech, Amgen, Italfarmaco: Consultancy; Novartis, Amgen, Celgene, Sanofi: Other: Travel, Accomodations, Expenses. Lo Coco:Lundbeck: Honoraria, Speakers Bureau; TEVA: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau.

Cardiac Tissue Factor Regulates Inflammation, Hypertrophy, and Heart Failure in Mouse Model of Type 1 Diabetes.

Patients with diabetes have an increased risk of heart failure (HF). Diabetes is highly prevalent in HF with preserved ejection fraction (HFpEF), which is on the rise worldwide. The role of diabetes in HF is less established, and available treatments for HF are not effective in patients with HFpEF. Tissue factor (TF), a transmembrane receptor, plays an important role in immune cell inflammation and atherothrombosis in diabetes. However, its role in diabetes-induced cardiac inflammation, hypertrophy, and HF has not been studied. In this study, we used wild-type (WT), heterozygous, and low-TF (with 1% human TF) mice to determine the role of TF in type 1 diabetes-induced HF. We found significant upregulation of cardiac TF mRNA and protein levels in diabetic WT hearts compared with nondiabetic controls. WT diabetic hearts also exhibited increased inflammation and cardiac hypertrophy versus controls. However, these changes in cardiac inflammation and hypertrophy were not found in low-TF mice with diabetes compared with their nondiabetic controls. TF deficiency was also associated with improved cardiac function parameters suggestive of HFpEF, which was evident in WT mice with diabetes. The TF regulation of inflammation and cardiac remodeling was further dependent on downstream ERK1/2 and STAT3 pathways. In summary, our study demonstrated an important role of TF in regulating diabetes-induced inflammation, hypertrophy, and remodeling of the heart leading to HFpEF.

Abstract 1534: Vimentin prevents a miR-dependent negative regulation of tissue factor mRNA during epithelial-mesenchymal transitions and facilitates early metastasis

Abstract Epithelial-Mesenchymal Transitions (EMTs) are high-profile in the field of circulating tumor cells (CTCs). EMT-shifted CTCs are considered to encompass pre-metastatic subpopulations though underlying molecular mechanisms remain elusive. Our previous work identified Tissue Factor (TF) as an EMT-induced gene providing tumor cells with coagulant properties and supporting metastatic colonization by CTCs. We here report that vimentin, the type III intermediate filament considered a canonical EMT marker, contributes to TF regulation and positively supports coagulant properties and early metastasis. Different evidence further pointed to a new post-transcriptional regulatory mechanism of TF mRNA by vimentin: (i) vimentin silencing accelerated TF mRNA decay after actinomycin-D treatment, reflecting TF mRNA stabilization, (ii) RNA immunoprecipitation revealed enriched levels of TF mRNA in vimentin immunoprecipitate, (iii) TF 3'-UTR-luciferase reporter vector assays implicated the 3'-UTR of TF mRNA in vimentin-dependent TF regulation, and (iv) using different TF 3'UTR luciferase reporter vectors mutated for potential miR binding sites and specific Target Site Blockers identified a key miR binding site in vimentin-dependent TF mRNA regulation. All together, these data support a novel mechanism by which vimentin interferes with a miR-dependent negative regulation of TF mRNA, thereby promoting coagulant activity and early metastasis of vimentin-expressing CTCs. Citation Format: Aline Vanwynsberghe, Marie-Emilie Francart, Christine Gilles. Vimentin prevents a miR-dependent negative regulation of tissue factor mRNA during epithelial-mesenchymal transitions and facilitates early metastasis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1534.

Evaluation of different commercial antibodies for their ability to detect human and mouse tissue factor by western blotting

BackgroundWestern blotting is used to measure protein expression in cells and tissues. Appropriate interpretation of resulting data is contingent upon antibody validation. ObjectivesWe assessed several commercial anti‐human and anti‐mouse tissue factor (TF) antibodies for their ability to detect TF by western blotting. Material and MethodsWe used human pancreatic cancer cell lines expressing different levels of TF and a mouse pancreatic cancer cell line expressing TF with a matched knockout derivative. ResultsHuman and mouse TF protein detected by western blotting correlated with levels of TF mRNA in these cell lines. The apparent molecular weight of TF is increased by N‐linked glycosylation and, as expected, deglycosylation decreased the size of TF based on western blotting. We found that four commercial anti‐human TF antibodies detected TF in a TF‐positive cell line HPAF‐II whereas no signal was observed in a TF‐negative cell line MIA PaCa‐2. More variability was observed in detecting mouse TF. Two anti‐mouse TF antibodies detected mouse TF in a TF‐positive cell line and no signal was observed in a TF knockout cell line. However, a third anti‐mouse TF antibody detected a nonspecific protein in both the mouse TF‐positive and TF‐negative cell lines. Two anti‐human TF antibodies that are claimed to cross react with mouse TF either recognized a nonspecific band or did not detect mouse TF. DiscussionOur results indicate that there is a range in quality of commercial anti‐TF antibodies. ConclusionWe recommend that all commercial antibodies should be validated to ensure that they detect TF.

Vimentin prevents a miR-dependent negative regulation of tissue factor mRNA during epithelial\u2013mesenchymal transitions and facilitates early metastasis

Epithelial–mesenchymal transitions (EMTs) are high-profile in the field of circulating tumor cells (CTCs). EMT-shifted CTCs are considered to encompass pre-metastatic subpopulations though underlying molecular mechanisms remain elusive. Our previous work identified tissue factor (TF) as an EMT-induced gene providing tumor cells with coagulant properties and supporting metastatic colonization by CTCs. We here report that vimentin, the type III intermediate filament considered a canonical EMT marker, contributes to TF regulation and positively supports coagulant properties and early metastasis. Different evidence further pointed to a new post-transcriptional regulatory mechanism of TF mRNA by vimentin: (1) vimentin silencing accelerated TF mRNA decay after actinomycin D treatment, reflecting TF mRNA stabilization, (2) RNA immunoprecipitation revealed enriched levels of TF mRNA in vimentin immunoprecipitate, (3) TF 3′-UTR-luciferase reporter vector assays implicated the 3′-UTR of TF mRNA in vimentin-dependent TF regulation, and (4) using different TF 3′UTR-luciferase reporter vectors mutated for potential miR binding sites and specific Target Site Blockers identified a key miR binding site in vimentin-dependent TF mRNA regulation. All together, these data support a novel mechanism by which vimentin interferes with a miR-dependent negative regulation of TF mRNA, thereby promoting coagulant activity and early metastasis of vimentin-expressing CTCs.

Nitric Oxide Mediates Downregulation of Tissue Factor Expression in Primary Human Pericytes through a p38 MAPK Signaling Pathway

Tissue factor (TF) is a high-affinity receptor for FVII/FVIIa that serves as a key initiator of hemostasis and is thought to also play a functional role in angiogenesis. Elevated TF expression has been linked to upregulated angiogenesis in malignant tumors, while reducing TF expression in experimental tumor models results in decreased angiogenesis. Although these data suggest that high TF expression is critical for angiogenesis, we have reported that TF expression declines significantly in pericytes that surround angiogenic vessels at sites of wound healing. This is the only known example of active TF downregulation, suggesting that pericytes regulate their expression of TF by a unique mechanism. Additionally, TF expression increases in response to many mediators, yet none that decrease TF expression have been described. The goal of this study was to characterize TF downregulation in pericytes and identify mediators of this process.We have previously shown that TF expression in primary cultures of human pericytes is not affected by treatment with various growth factors or inflammatory stimuli, but decreases significantly in response to phorbol 12-myristate 13-acetate (PMA). PMA triggers degradation of TF protein and inhibition of TF mRNA synthesis, both in a Protein Kinase C (PKC)- dependent manner. To identify other signaling molecules in this pathway we used chemical inhibitors to block the activity of signaling molecules downstream of PKC before adding PMA to pericyte cultures. Inhibition of NF-kB, ERK1/2, AKT, JNK, and p38 MAPK did not block degradation of TF protein. However, pericytes that received a p38 inhibitor (SB202190) alone demonstrated significant reduction of TF mRNA. Treatment with SB202190 followed by PMA produced an additive effect on TF mRNA reduction. Western blotting showed that prolonged PMA treatment (>4 hours) produced a sustained decrease in p38 phosphorylation. These data suggest that PMA inhibits p38 activity, and that p38 confers stability to TF mRNA.We have previously found that basic Fibroblast Growth Factor (bFGF) triggers downregulation of pericyte TF a co-culture system with human microvascular endothelial cells. However, transferring bFGF-conditioned endothelial cell media to pericytes cultured alone failed to reproduce TF loss. bFGF has been shown to stimulate nitric oxide (NO) production, and both bFGF and NO have been linked to angiogenesis. This led us to consider NO as a potential labile mediator of TF downregulation. ±6.1%, p<0.01). However, expression of TF mRNA was not reduced at this time, as it is during culture with PMA. Pericytes treated with DETA NO demonstrated sustained p38 phosphorylation for up to 8 hours. Taken together, these data suggest that DETA NO downregulates TF protein but maintains basal levels of TF mRNA, potentially in a p38-dependent manner.Based on these data, we hypothesize that the p38 signaling axis is a key component of a unique pathway of TF regulation in pericytes, and that endothelial nitric oxide contributes to downregulation of pericyte TFin vivo at sites of physiologic angiogenesis. DisclosuresHoffman:Novo Nordisk A/S: Consultancy, Honoraria, Research Funding.

Experimental hypercoagulable state induced by tissue factor expression in monocyte-derived dendritic cells and its modulation by C1 inhibitor.

The crosstalk between immune and coagulation systems plays pivotal roles in host defense, which may involve monocyte-derived dendritic cells (moDCs). Our objectives were to elucidate the role of moDCs in coagulation under inflammatory conditions and the involvement of the complement system. We assessed the effects of lipopolysaccharide (LPS)-stimulated moDCs on coagulation using whole blood thromboelastometry in the presence of complement inhibitors. The sum of clotting time and clot formation time (CT plus CFT) in whole blood thromboelastometry was significantly more reduced in the presence of moDCs than in the absence of monocytes or moDCs and in the presence of monocytes, indicating a more potent coagulability of moDCs. The mRNA expression of coagulation-related proteins in moDCs was analyzed by quantitative PCR, which showed an increase only in the mRNA levels of tissue factor (TF). TF protein expression was assessed by western blot analysis and an activity assay, revealing higher TF expression in moDCs than that in monocytes. The in vitro moDC-associated hypercoagulable state was suppressed by a TF-neutralizing antibody, whereas LPS enhanced the in vitro hypercoagulation further. C1 inhibitor suppressed the in vitro LPS-enhanced whole blood hypercoagulability in the presence of moDCs and the increased TF expression in moDCs. These results suggest a significant role of moDCs and the complement system through TF expression in a hypercoagulable state under inflammatory conditions and demonstrate the suppressive effects of C1 inhibitor on moDC-associated hypercoagulation.

Comparison of tissue factor expression and activity in foetal and adult endothelial cells

: Tissue factor (TF) is not usually expressed by endothelial cells but can be induced in these cells by inflammatory cytokines. Many studies have used human umbilical vein endothelial cells (HUVEC) as a model to examine the regulation of TF expression. However, there is a question as to whether this reflects TF expression in adult endothelial cells. This study compared TF expression and the release of TF-positive microvesicles in HUVEC and adult human dermal blood endothelial cells (HDBEC) in response to tumour necrosis factor α (TNFα) and interleukin-1 β (IL-1β). Cells were treated with the inflammatory cytokines and TF mRNA and total protein expression was examined by real-time RT-PCR and TF ELISA. Cell surface TF activity was measured in the calibrated automated thrombogram assay, as were microvesicle concentrations and microvesicle-associated TF activity. The TF antigen content of the microvesicles was determined by TF ELISA. Both HUVEC and HDBEC expressed increased levels of TF mRNA in response to TNFα and IL-1β within 2 h. TF antigen expression increased in both cell types, reaching a maximum at 6 h, with HUVEC expressing significantly higher levels compared with HDBEC in response to TNFα. However, increases in TF-specific thrombin generation were similar on both HUVEC and HDBEC and both cell types also released comparable levels of TF-positive microvesicles. HUVEC and HDBEC respond similarly to TNFα and IL-1β in terms of TF expression, and both are suitable models to examine cell surface TF activity and TF-positive microvesicle release in endothelial cells.

Endothelial-specific deletion of autophagy-related 7 (ATG7) attenuates arterial thrombosis in mice

BackgroundThrombosis persists as a leading cause of morbidity and mortality. Given that endothelial cells (ECs) play a central role in regulating thrombosis, understanding the molecular endothelial cues that regulate susceptibility or resistance to thrombosis have important translational implications. Accordingly, we evaluated the role of endothelial autophagy in the development of thrombosis. MethodsWe generated mice in which the essential autophagy-related 7 (ATG7) gene was conditionally deleted from ECs (EC-ATG7−/− mice). Three in vivo models of thrombosis were used, and mechanistic studies were conducted with cultured human umbilical vein endothelial cells (HUVECs). ResultsWe silenced ATG7 in HUVECs and observed >60% decreases in tumor necrosis factor (TNF)-α–induced tissue factor (TF) transcript levels, protein expression, and activity. TF mRNA levels in the carotid arteries of EC-ATG7−/− mice subjected to the prothrombotic stimulus FeCl3 were lower than those in the similarly treated wild-type (WT) littermate group. Compared with WT mice, EC-ATG7−/− mice exhibited prolonged time to carotid (2-fold greater) and mesenteric (1.3-fold greater) artery occlusion following FeCl3 injury. The thrombi generated in laser-injured cremasteric arterioles were smaller in EC-ATG7−/− mice compared with WT mice, and took 2.3-fold longer to appear. ConclusionsTaken together, these results provide definitive evidence that loss of endothelial ATG7 attenuates thrombosis and reduces the expression of TF. Our findings demonstrate that endothelial ATG7, and thus autophagy, is a critical and previously unrecognized target for modulating the susceptibility to thrombosis.

Therapeutic regulation of systemic inflammation in xenograft recipients.

Inflammation is known to preclude tolerance after transplantation. We have previously shown that systemic inflammation in xenograft recipients (SIXR) precedes activation of coagulation in the absence of T cell responses. Accordingly, SIXR may amplify innate and adaptive immune responses against xenografts after pig-to-primate xenotransplantation, even with efficient immunosuppressive therapy. We evaluated the impact of anti-inflammatory agents on pro-inflammatory cytokines and chemokines in pig artery patch and heart xenograft recipients. Baboons received an artery patch (Group1, n=8) or heart (Group2, n=4) from genetically engineered pigs. All baboons received lymphodepletion with thymoglobulin (ATG) and costimulation blockade-based immunosuppression (anti-CD40 and/or CTLA4Ig). In Group1, baboons received either (i) no anti-inflammatory agents (n=2), (ii) cobra venom factor (CVF, n=2), (iii) α1-antitrypsin (AAT, n=2), or (iv) interleukin (IL)-6 receptor antagonist (IL-6RA, n=2). In Group2, all baboon received corticosteroids, either without (n=2) or with (n=2) IL-6RA. Serum IFN-γ, TNF-α, IL-1β, IL-17, IL-6, IL-8, MCP-1, and sCD40L levels were measured by Luminex. Fibrinogen, D-dimers, and C-reactive protein (C-RP) were also measured. Recipient baboon T cell proliferation was evaluated by mixed lymphocyte reaction (MLR) before and after transplantation. Pig and baboon tissue factor (TF) mRNA levels in heart xenografts were measured by RT-PCR. In no recipient was a marked increase in T cell response to pig cells observed after transplantation. In Groups 1 and 2, post-transplantation levels of IFN-γ, TNF-α, IL-1β, and IL-17 remained comparable to or lower than pre-transplant levels, except in one heart recipient that succumbed to CMV infection. In Group1, when no anti-inflammatory agent was administered, post-transplant levels of IL-6, IL-8, and MCP-1 were elevated. After CVF, IL-6, IL-8, and MCP-1 remained low. After IL-6RA, IL-6 and MCP-1 were elevated. After AAT, IL-8 was elevated. sCD40L became elevated intermittently in most recipients irrespective of the administered anti-inflammatory agent. In Group2, IL-6 was transiently elevated, particularly after IL-6RA administration. MCP-1 gradually increased by 2months in Group2 recipients. sCD40L generally remained low except in one recipient. In Group1 and Group2 recipients, C-RP levels were elevated except after IL-6RA administration, while D-dimers were elevated regardless of administration of anti-inflammatory agent. In Group2, pig TF mRNA levels were increased in heart xenografts compared to naive pig hearts, irrespective of IL-6 receptor antagonist administration. Additionally, baboon TF mRNA levels were detectable in heart xenografts, but not in naive pig hearts. Some pro-inflammatory cytokines and chemokines are elevated in xenograft recipients, even with efficient T cell-directed immunosuppressive therapy. Persistent elevation of D-dimers, and individual cytokines and chemokines suggest a continuous inflammatory response, despite administration of anti-inflammatory agents. Systemic administration of combined anti-inflammatory agents as well as complement regulation may be essential to prevent SIXR after xenotransplantation.

IL-33 stimulates the release of procoagulant microvesicles from human monocytes and differentially increases tissue factor in human monocyte subsets.

Monocytes and monocyte-derived microvesicles (MVs) are the main source of circulating tissue factor (TF). Increased monocyte TF expression and increased circulating levels of procoagulant MVs contribute to the formation of a prothrombotic state in patients with cardiovascular disease. Interleukin (IL)-33 is a pro-inflammatory cytokine involved in atherosclerosis and other inflammatory diseases, but its role in regulating thrombosis is still unclear. The aim of the present study was to investigate the effects of IL-33 on the procoagulant properties of human monocytes and monocyte-derived MVs. IL-33 induced a time- and concentration-dependent increase of monocyte TF mRNA and protein levels via binding to the ST2-receptor and activation of the NF-κB-pathway. The IL-33 treated monocytes also released CD14+TF+ MVs and IL-33 was found to increase the TF activity of both the isolated monocytes and monocyte-derived MVs. The monocytes were classified into subsets according to their CD14 and CD16 expression. Intermediate monocytes (IM) showed the highest ST2 receptor expression, followed by non-classical monocytes (NCM), and classical monocytes (CM). IL-33 induced a significant increase of TF only in the IM (p<0.01), with a tendency in NCM (p=0.06), but no increase was observed in CM. Finally, plasma levels of IL-33 were positively correlated with CD14+TF+ MVs in patients undergoing carotid endarterectomy (r=0.480; p=0.032; n=20). We hereby provide novel evidence that the proinflammatory cytokine IL-33 induces differential TF expression and activity in monocyte subsets, as well as the release of procoagulant MVs. In this manner, IL-33 may contribute to the formation of a prothrombotic state characteristic for cardiovascular disease.

123 - Inhibition of the Pro-Atherogenic Action of Serum Amyloid a (SAA) by Pharmacological Blockade of NFκB Pathway

The acute phase protein serum amyloid A (SAA) is a biomarker of inflammation. Elevated circulating SAA in chronic inflammatory disorders such as diabetes mellitus is associated with endothelial dysfunction and the earliest stages of atherosclerosis. Binding of SAA to cell receptors leads to increased production of mRNA encoding tumor necrosis factor (TNF), tissue factor (TF) and cytokines such as interleukin-6 (IL-6); the proteins produced by these genes display pro-inflammatory and pro-thrombotic activities that may be involved in promoting endothelial dysfunction. Activation of the transcription factor NFκB appears to be a central canonical pathway for SAA-mediated endothelial cell dysfunction. Targeting NFκB, using the specific inhibitor BAY11-7082, may be more effective at inhibiting SAA-mediated endothelial dysfunction than a pharmaceutical cocktail that targets its receptors. Human carotid artery endothelial (HCtAE) cells were cultured to confluence under normoglycaemic (5mM glucose) or hyperglycaemic conditions (25mM glucose) conditions and pre-incubated (1.5 h; 37°C) with 10µM BAY11-7082 or vehicle (control) followed by 10μg/mL SAA (4.5 h; 37°C). Notably, TF and TNF gene expression increased markedly in HCtAE cells after SAA stimulation whereas HCtAE cells pre-treated with BAY11-7082 (with SAA) showed TF and TNF mRNA levels similar to that determined in control cells (minus SAA). In the absence of BAY11-7082, both intracellular TNF and IL-6 protein increased following incubation with SAA as determined by immunofluorescence microscopy. This SAA activity was inhibited by BAY11-7082. ELISA analysis of HCtAE cell pellets and overlying supernatant confirmed the immunofluorescence data with SAA activity inhibited by BAY11-7082; IL-6 showed a greater sensitivity to the drug than TNF. In ex-vivo leukocyte adhesion studies of mice aorta, pre-treatment with BAY11-7082 showed a significant reduction in leukocyte adhesion compared with SAA-alone treated mice. Together these data suggest that inhibition of NFκB activation may protect the endothelium from the action of SAA by inhibiting pro-inflammatory and pro-thrombotic pathways.

Histones Induce the Procoagulant Phenotype of Endothelial Cells through Tissue Factor Up-Regulation and Thrombomodulin Down-Regulation.

The high circulating levels of histones found in various thrombotic diseases may compromise the anticoagulant barrier of endothelial cells. We determined how histones affect endothelial procoagulant tissue factor (TF) and anticoagulant thrombomodulin (TM). Surface antigens, soluble forms, and mRNA levels of TF and TM were measured by flow cytometry, ELISA, and real-time RT-PCR, respectively. TF and TM activity were measured using procoagulant activity, thrombin generation, or chromogenic assays. Involvement of the toll-like receptor (TLR) was assessed using the neutralizing antibodies. Histones dose-dependently induced surface antigens, activity and mRNA levels of endothelial TF. Histone-treated endothelial cells significantly shortened the lag time and enhanced the endogenous thrombin potential of normal plasma, which was normalized by a TF neutralizing antibody. Histones induced phosphatidylserine and protein-disulfide isomerase expression in endothelial cells. Histones also reduced the surface antigen, activity, and mRNA levels of endothelial TM. Polysialic acid and heparin reversed the histone-induced TF up-regulation and TM down-regulation. Activated protein C did not affect the TF up-regulation, but interrupted TM down-regulation. TLR2, and TLR4 inhibitors partially blocked the TF up-regulation. Histones induced the endothelial procoagulant phenotype through TF up-regulation and TM down-regulation. The effects of histones were partly mediated by TLR2, TLR4. Strategies to inhibit the harmful effects of histones in endothelial cells may be required in order to prevent a thrombotic environment.

The role of tissue factor and autophagy in pulmonary vascular remodeling in a rat model for chronic thromboembolic pulmonary hypertension.

BackgroundFew reports have examined tissue factor (TF) and autophagy expression in chronic pulmonary thromboembolic hypertension (CTEPH) animal models. Objectives: To investigate the role of tissue factor (TF), autophagy and their interactions during chronic thromboembolic pulmonary hypertension (CTEPH) pathogenesis in a rat model.MethodsAutologous blood clots were repeatedly injected into the left jugular vein of rats with injecting endogenous fibrinolysis inhibitor tranexamic acid (TXA). Mean pulmonary arterial pressure (mPAP), histopathology and TF, Beclin-1 and microtubule-associated protein 1 light chain (LC3) expression levels were detected.ResultsThe mPAP and vessel wall area/total area (WA/TA) ratio in the experiment group increased significantly (P < 0.05). TF mRNA and protein expression levels in the experiment group increased significantly (P < 0.05). Beclin-1 and LC3B mRNA and protein expression levels were lower in the experiment group (P < 0.05). The mPAP had a positive correlation with WA/TA ratio (r = 0.955, P < 0.05). Beclin-1 and LC3B protein expression had a negative correlation with the WA/TA ratio (r = -0.963, P < 0.05, r = -0.965, P < 0.05, respectively). TF protein expression had a negative correlation with both Beclin-1 and LC3B protein expression (r = -0.995, P <0.05, r = -0972, P < 0.05, respectively).ConclusionsA rat model of CTEPH can be established by repeatedly introducing autologous blood clots into the pulmonary artery with injecting TXA. TF and autophagy may play a key role during CTEPH pathogenesis, especially in vascular remodeling.

Abstract 377: Phorbol 12-myristate 13-acetate Downregulates Tissue Factor Gene Expression in Human Pericytes

Tissue factor (TF) is a transmembrane receptor for factor VII/VIIa that plays a central role in hemostasis and angiogenesis. While TF is generally upregulated in pathologic conditions, we have reported that TF is downregulated in pericytes around vessels near a healing cutaneous wound. As the first demonstration of physiologic downregulation of TF, this finding suggested a potential means of modulating TF expression for therapeutic purposes. The goal of this study was to contribute to implementation of future therapies by elucidating mechanisms that regulate loss pericyte TF. To identify mediators of TF downregulation we utilized primary cultures of human placental pericytes to screen growth factors involved in wound healing including TGFβ, bFGF, VEGF, PDGF and ANG2. None significantly reduced pericyte TF expression as assessed by western blotting. We next tested agents that directly activate signaling pathways. Phorbol 12-myristate 13-acetate (PMA) triggered ~60% reduction in TF protein 4 hours after treatment. Complete loss of TF occurred by 8 hours (p&lt;0.001) and remained until the experiment was terminated 24 hours after PMA addition. These results suggested that TF loss is mediated, at least in part, by downregulation of TF gene expression. We utilized qRT-PCR to determine the effects of PMA on synthesis of TF transcripts 4, 8, 12, and 24 hours after treatment. TF mRNA levels were unchanged 4 hours after treatment. However, TF transcripts decreased 4 and 6 fold 8 hours and 12 hours after PMA, respectively (p&lt;0.01). 24 hours after treatment the amount of TF mRNA rebounded, yet remained 2 fold lower than the control (p&lt;0.05). To determine if the decrease in TF transcripts is caused by mRNA destabilization, pericytes were treated with actinomycin D prior to PMA. Degradation of TF transcripts in PMA-treated cells was similar to that of DMSO-treated control cells at all time points (p=ns), indicating that PMA-mediated downregulation of TF expression occurs primarily through inhibition of mRNA synthesis rather than through destabilization of existing transcripts. In conclusion, our results demonstrate a role for transcriptional downregulation in PMA-mediated loss of pericyte TF protein, findings that pave the way for future in vivo studies of wound healing.