Tissue Factor and Factor VIIa Receptor/Ligand Interactions Induce Proinflammatory Effects in Macrophages

Macrophage fate: to kill or not to kill?

Macrophages are dynamic innate immune cells that either reside in tissue, serving as sentinels, or recruited as monocytes from bone marrow into inflamed and infected tissue. In response to cues in the tissue microenvironment (TME), macrophages polarize on a continuum toward M1 or M2 with diverse roles in progression and resolution of disease. M1-like macrophages exhibit proinflammatory functions with antimicrobial and anti-tumorigenic activities, while M2-like macrophages have anti-inflammatory functions that generally resolve inflammatory responses and orchestrate a tissue healing process. Given these opposite phenotypes, proper spatiotemporal coordination of macrophage polarization in response to cues within the TME is critical to effectively resolve infectious disease and regulate wound healing. However, if this spatiotemporal coordination becomes disrupted due to persistent infection or dysregulated coagulation, macrophages' inappropriate response to these cues will result in the development of diseases with clinically unfavorable outcomes. Since plasticity and heterogeneity are hallmarks of macrophages, they are attractive targets for therapies to reprogram toward specific phenotypes that could resolve disease and favor clinical prognosis. In this review, we discuss how basic science studies have elucidated macrophage polarization mechanisms in TMEs during infections and inflammation, particularly coagulation. Therefore, understanding the dynamics of macrophage polarization within TMEs in diseases is important in further development of targeted therapies.

African Swine Fever Virus I267L Is a Hemorrhage-Related Gene Based on Transcriptome Analysis

African swine fever (ASF) is an acute and severe disease transmitted among domestic pigs and wild boars. This disease is notorious for its high mortality rate and has caused great losses to the world's pig industry in the past few years. After infection, pigs can develop symptoms such as high fever, inflammation, and acute hemorrhage, finally leading to death. African swine fever virus (ASFV) is the causal agent of ASF; it is a large DNA virus with 150-200 genes. Elucidating the functions of each gene could provide insightful information for developing prevention and control methods. Herein, to investigate the function of I267L, porcine alveolar macrophages (PAMs) infected with an I267L-deleted ASFV strain (named ∆I267L) and wild-type ASFV for 18 h and 36 h were taken for transcriptome sequencing (RNA-seq). The most distinct different gene that appeared at both 18 hpi (hours post-infection) and 36 hpi was F3; it is the key link between inflammation and coagulation cascades. KEGG analysis (Kyoto encyclopedia of genes and genomes analysis) revealed the complement and coagulation cascades were also significantly affected at 18 hpi. Genes associated with the immune response were also highly enriched with the deletion of I267L. RNA-seq results were validated through RT-qPCR. Further experiments confirmed that ASFV infection could suppress the induction of F3 through TNF-α, while I267L deletion partially impaired this suppression. These results suggest that I267L is a pathogenicity-associated gene that modulates the hemorrhages of ASF by suppressing F3 expression. This study provides new insights into the molecular mechanisms of ASFV pathogenicity and potential targets for ASFV prevention and control.

NAFLD: An Emerging Causal Factor for Cardiovascular Disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease worldwide that poses a significant threat to human health. Cardiovascular disease (CVD) is the leading cause of mortality in NAFLD patients. NAFLD and CVD share risk factors such as obesity, insulin resistance, and type 2 diabetes. However, whether NAFLD is a causal risk factor for CVD remains a matter of debate. This review summarizes the evidence from prospective clinical and Mendelian randomization studies that underscore the potential causal relationship between NAFLD and CVD. The mechanisms of NAFLD contributing to the development of CVD and the necessity of addressing CVD risk while managing NAFLD in clinical practice are also discussed.

Pretreatment with Eupatilin Attenuates Inflammation and Coagulation in Sepsis by Suppressing JAK2/STAT3 Signaling Pathway

Purpose

Sepsis is an aggressive and life-threatening organ dysfunction induced by infection. Excessive inflammation and coagulation contribute to the negative outcomes for sepsis, resulting in high morbidity and mortality. In this study, we explored whether Eupatilin could alleviate lung injury, reduce inflammation and coagulation during sepsis.

Methods

We constructed an in vitro sepsis model by stimulating RAW264.7 cells with 1 μg/mL lipopolysaccharide (LPS) for 6 hours. The cells were divided into control group, LPS group, LPS+ Eupatilin (Eup) group, and Eup group to detect their cell activity and inflammatory cytokines and coagulation factor levels. Cells in LPS+Eup and Eup group were pretreated with Eupatilin (10μM) for 2 hours. In vivo, mice were divided into sham operation group, cecal ligation and puncture (CLP) group and Eup group. Mice in the CLP and Eup groups were pretreated with Eupatilin (10mg/kg) for 2 hours by gavage. Lung tissue and plasma were collected and inflammatory cytokines, coagulation factors and signaling were measured.

Results

In vitro, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and tissue factor (TF) expression in LPS-stimulated RAW264.7 cells was downregulated by Eupatilin (10μM). Furthermore, Eupatilin inhibited phosphorylation of the JAK2/STAT3 signaling pathway and suppressed p-STAT3 nuclear translocation. In vivo, Eupatilin increased the survival rate of the mice. In septic mice, plasma concentrations of TNF-α, IL-1β and IL-6, as well as TF, plasminogen activator inhibitor 1 (PAI-1), D-dimer, thrombin-antithrombin complex (TAT) and fibrinogen were improved by Eupatilin. Moreover, Eupatilin alleviated lung injury by improving the expression of inflammatory cytokines and TF, fibrin deposition and macrophage infiltration in lung tissue.

Conclusion

Our results revealed that Eupatilin may modulate inflammation and coagulation indicators as well as improve lung injury in sepsis via the JAK2/STAT3 signaling pathway.

Reactive Oxygen Species Scavenging Nanomedicine for the Treatment of Ischemic Heart Disease

Ischemic heart disease (IHD) is the leading cause of disability and mortality worldwide. Reactive oxygen species (ROS) have been shown to play key roles in the progression of diabetes, hypertension, and hypercholesterolemia, which are independent risk factors that lead to atherosclerosis and the development of IHD. Engineered biomaterial-based nanomedicines are under extensive investigation and exploration, serving as smart and multifunctional nanocarriers for synergistic therapeutic effect. Capitalizing on cell/molecule-targeting drug delivery, nanomedicines present enhanced specificity and safety with favorable pharmacokinetics and pharmacodynamics. Herein, the roles of ROS in both IHD and its risk factors are discussed, highlighting cardiovascular medications that have antioxidant properties, and summarizing the advantages, properties, and recent achievements of nanomedicines that have ROS scavenging capacity for the treatment of diabetes, hypertension, hypercholesterolemia, atherosclerosis, ischemia/reperfusion, and myocardial infarction. Finally, the current challenges of nanomedicines for ROS-scavenging treatment of IHD and possible future directions are discussed from a clinical perspective.

Recent advance in treatment of atherosclerosis: Key targets and plaque-positioned delivery strategies

Atherosclerosis, a chronic inflammatory disease of vascular wall, is a progressive pathophysiological process with lipids oxidation/depositing initiation and innate/adaptive immune responses. The coordination of multi systems covering oxidative stress, dysfunctional endothelium, diseased lipid uptake, cell apoptosis, thrombotic and pro-inflammatory responding as well as switched SMCs contributes to plaque growth. In this circumstance, inevitably, targeting these processes is considered to be effective for treating atherosclerosis. Arriving, retention and working of payload candidates mediated by targets in lesion direct ultimate therapeutic outcomes. Accumulating a series of scientific studies and clinical practice in the past decades, lesion homing delivery strategies including stent/balloon/nanoparticle-based transportation worked as the potent promotor to ensure a therapeutic effect. The objective of this review is to achieve a very brief summary about the effective therapeutic methods cooperating specifical targets and positioning-delivery strategies in atherosclerosis for better outcomes.

Role of lungs in the hemostasis system (review of literature)

The lung tissue contains various hemostatic system elements, which can be released from the lungs, both under physiological and pathological conditions. The COVID-19 pandemic has led to an increase in the number of patients with acute respiratory distress syndrome (ARDS) in intensive care units worldwide. When the lungs are damaged, coagulation disorders are mediated by tissue factor (TF) - factor VIIa (F VIIa), and inhibition of this pathway completely eliminates intrapulmonary fibrin deposition. A tissue factor pathway inhibitor TFPI also contributes to pulmonary coagulationdisturbance in ARDS. Pulmonary coagulationdisturbance caused by pneumonia can worsen the damage to the lungs and thus contribute to the progression of the disease. Cytokines are the main linking factors between inflammation and changes in blood clotting and fibrinolysis. The sources of proinflammatory cytokines in the lungs are probably alveolar macrophages. The activation of alveolar macrophages occurs through the nuclear factor kappa-bi (NF-κB), which controls thetranscription of the expression of immune response genes, cell apoptosis, which leads to the development of inflammation and autoimmune diseases as a result of direct stimulation of TF activation. Conversely,coagulation itself can affect bronchoalveolar inflammation. Coagulation leads to the formation of proteases that interact with specific cellular receptors, activating intracellular signaling pathways. The use of anticoagulant therapy, which also has an anti-inflammatory effect, perhaps one of the therapeutic targets for coronavirus infection.The difficulty here is that it seems appropriate to study anticoagulant interventions' influence on clinically significant cardio-respiratory parameters.

Acquired Coagulopathy With Immune Checkpoint Inhibitors: An Underrecognized Association Between Inflammation and Coagulation

Introduction

Immune-related adverse events affecting virtually every organ system have been described in individuals receiving immune checkpoint inhibitors. The spectrum of hematologic adverse effects is diverse and includes autoimmune cytopenias, hemolysis, or inhibition of coagulation factors. The interplay of inflammation and the coagulation cascade is complex, and immune checkpoint inhibitors can induce coagulopathy by disrupting the intricate link between these pathways.

Methods

We report acquired coagulopathy in two patients treated with the programmed death-ligand 1 antibodies, atezolizumab and avelumab, respectively. Clinical findings and results of extensive laboratory workup are reported. We hypothesize that cytokine release is a potential pathologic mechanism responsible for acquired coagulopathy.

Results

Symptoms included fever, fatigue, and disorientation in one patient and fever, myalgias, and skin rash in the other. Laboratory features included an abnormal coagulation profile; low fibrinogen levels; and elevated D-dimer, ferritin, and triglycerides. Treatment consisted of intravenous glucocorticoids in both cases and the use of fresh frozen plasma, cryoprecipitate, and clotting factor support in one patient.

Conclusions

Recognition of acquired coagulopathy as a complication of immunotherapy and its aggressive management are crucial to reduce morbidity and mortality associated with this condition.

Breaking the vicious loop between inflammation, oxidative stress and coagulation, a novel anti-thrombus insight of nattokinase by inhibiting LPS-induced inflammation and oxidative stress

Thrombosis is a principle cause of cardiovascular disease, the leading cause of morbidity and mortality worldwide; however, the conventional anti-thrombotic approach often leads to bleeding complications despite extensive clinical management and monitoring. In view of the intense crosstalk between inflammation and coagulation, plus the contributing role of ROS to both inflammation and coagulation, it is highly desirable to develop safer anti-thrombotic agent with preserved anti-inflammatory and anti-oxidative stress activities. Nattokinase (NK) possesses many beneficial effects on cardiovascular system due to its strong thrombolytic and anticoagulant activities. Herein, we demonstrated that NK not only effectively prevented xylene-induced ear oedema in mice, but also remarkably protected against LPS-induced acute kidney injury in mice through restraining inflammation and oxidative stress, a central player in the initiation and progression of inflammation. Fascinatingly, in line with our in vivo data, NK elicited prominent anti-inflammatory activity in RAW264.7 macrophages via suppressing the LPS-induced TLR4 and NOX2 activation, thereby repressing the corresponding ROS production, MAPKs activation, and NF-κB translocation from the cytoplasm to the nucleus, where it mediates the expression of pro-inflammatory mediators, such as TNF-α, IL-6, NO, and PAI-1 in activated macrophage cells. In particular, consistent with the macrophage studies, NK markedly inhibited serum PAI-1 levels induced by LPS, thereby blocking the deposition of fibrin in the glomeruli of endotoxin-treated animals. In summary, we extended the anti-thrombus mechanism of NK by demonstrating the anti-inflammatory and anti-oxidative stress effects of NK in ameliorating LPS-activated macrophage signaling and protecting against LPS-stimulated AKI as well as glomeruler thrombus in mice, opening a comprehensive anti-thrombus strategy by breaking the vicious cycle between inflammation, oxidative stress and thrombosis.

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NK protects against LPS-induced AKI via inhibiting inflammation and oxidative stress.

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NK inhibits LPS-induced TRL4 and NOX2 activation in macrophages.

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NK inhibits inflammation and oxidative stress both in vitro and in vivo.

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NK inhibits LPS-induced PAI-I levels, thereby blocking glomerular thrombus in mice.

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NK may break the vicious loop between inflammation, oxidative stress and coagulation.

Tissue factor pathway inhibitor primes monocytes for antiphospholipid antibody-induced thrombosis

Antiphospholipid antibodies (aPLs) with complex lipid and/or protein reactivities cause complement-dependent thrombosis and pregnancy complications. Although cross-reactivities with coagulation regulatory proteins contribute to the risk for developing thrombosis in patients with antiphospholipid syndrome, the majority of pathogenic aPLs retain reactivity with membrane lipid components and rapidly induce reactive oxygen species-dependent proinflammatory signaling and tissue factor (TF) procoagulant activation. Here, we show that lipid-reactive aPLs activate a common species-conserved TF signaling pathway. aPLs dissociate an inhibited TF coagulation initiation complex on the cell surface of monocytes, thereby liberating factor Xa for thrombin generation and protease activated receptor 1/2 heterodimer signaling. In addition to proteolytic signaling, aPLs promote complement- and protein disulfide isomerase-dependent TF-integrin β1 trafficking that translocates aPLs and NADPH oxidase to the endosome. Cell surface TF pathway inhibitor (TFPI) synthesized by monocytes is required for TF inhibition, and disabling TFPI prevents aPL signaling, indicating a paradoxical prothrombotic role for TFPI. Myeloid cell-specific TFPI inactivation has no effect on models of arterial or venous thrombus development, but remarkably prevents experimental aPL-induced thrombosis in mice. Thus, the physiological control of TF primes monocytes for rapid aPL pathogenic signaling and thrombosis amplification in an unexpected crosstalk between complement activation and coagulation signaling.

Biological profile of monocyte-derived macrophages in coronary heart disease patients: implications for plaque morphology

The prevalence of a macrophage phenotype in atherosclerotic plaque may drive its progression and/or instability. Macrophages from coronary plaques are not available, and monocyte-derived macrophages (MDMs) are usually considered as a surrogate. We compared the MDM profile obtained from coronary artery disease (CAD) patients and healthy subjects, and we evaluated the association between CAD MDM profile and in vivo coronary plaque characteristics assessed by optical coherence tomography (OCT). At morphological analysis, MDMs of CAD patients had a higher prevalence of round than spindle cells, whereas in healthy subjects the prevalence of the two morphotypes was similar. Compared to healthy subjects, MDMs of CAD patients had reduced efferocytosis, lower transglutaminase-2, CD206 and CD163 receptor levels, and higher tissue factor (TF) levels. At OCT, patients with a higher prevalence of round MDMs showed more frequently a lipid-rich plaque, a thin-cap fibroatheroma, a greater intra-plaque macrophage accumulation, and a ruptured plaque. The MDM efferocytosis correlated with minimal lumen area, and TF levels in MDMs correlated with the presence of ruptured plaque. MDMs obtained from CAD patients are characterized by a morpho-phenotypic heterogeneity with a prevalence of round cells, showing pro-inflammatory and pro-thrombotic properties. The MDM profile allows identifying CAD patients at high risk.

The Bidirectional Interactions Between Inflammation and Coagulation in Fracture Hematoma

IMPACT STATEMENT

The review leads to better understanding of the interrelation between inflammation mediators and coagulation factors in the early fracture hematoma, and their influences on hematoma formation in the beginning of fracture healing. Furthermore, development of therapies aimed at simultaneous modulation of both coagulation factors and inflammation factors that affect hematoma structure, rather than specific factors, may be most promising.

Molecular characterization of a tissue factor gene from ayu: A pro-inflammatory mediator via regulating monocytes/macrophages

Tissue factor (TF) plays an important role in the host's immune system as the principal initiator of coagulation. However, the precise function of TF in teleosts remains unclear. We determined the cDNA sequence of TF from ayu Plecoglossus altivelis (PaTF). The PaTF transcript was expressed in all tested tissues, and changes in expression were observed in tissues and monocytes/macrophages (MO/MФ) upon infection with Vibrio anguillarum. PaTF was prokaryotically expressed and purified to prepare anti-PaTF antibodies. Western blot analysis revealed that native PaTF was glycosylated in thrombocytes, but not in ayu MO/MФ. Microparticles could transfer PaTF to thrombocytes. PaTF neutralization or knockdown led to anti-inflammatory status in ayu MO/MФ upon V. anguillarum infection. PaTF neutralization reduced the apoptosis of ayu MO/MФ and improve survival rate in V. anguillarum-infected ayu. Our results indicate that PaTF plays a role in ayu immune response against bacterial infection as a pro-inflammatory mediator.

Extracellular haemoglobin upregulates and binds to tissue factor on macrophages: Implications for coagulation and oxidative stress

The mechanisms of crosstalk between haemolysis, coagulation and innate immunity are evolutionarily conserved from the invertebrate haemocyanin to the vertebrate haemoglobin (Hb). In vertebrates, extracellular Hb resulting from haemolytic infections binds bacterial lipopolysaccharide (LPS) to unleash the antimicrobial redox activity of Hb. Because bacterial invasion also upregulates tissue factor (TF), the vertebrate coagulation initiator, we asked whether there may be functional interplay between the redox activity of Hb and the procoagulant activity of TF. Using real-time PCR, TF-specific ELISA, flow cytometry and TF activity assay, we found that Hb upregulated the expression of functional TF in macrophages. ELISA, flow cytometry and immunofluorescence microscopy showed binding between Hb and TF, in isolation and in situ. Bioinformatic analysis of Hb and TF protein sequences showed co-evolution across species, suggesting that Hbβ binds TF. Empirically, TF suppressed the LPS-induced activation of Hb redox activity. Furthermore, Hb desensitised TF to the effects of antioxidants like glutathione or serum. This bi-directional regulation between Hb and TF constitutes a novel link between coagulation and innate immunity. In addition, induction of TF by Hb is a potentially central mechanism for haemolysis to trigger coagulation.

Modeling aging in HIV infection in nonhuman primates to address an emerging challenge of the post-ART era

The advent of antiretroviral therapy (ART) has dramatically improved both quality and length of life for subjects infected with human immunodeficiency virus (HIV), delaying or preventing progression to acquired immunodeficiency syndrome (AIDS). However, the virus induces aging-related changes to the immune system which confound treatment. Additionally, the normal physiologic events that occur during aging lead to deficiencies in immunity which not only exacerbate HIV pathogenesis but also trigger a variety of comorbidities. Here, the synergistic linkage between aging and HIV infection is examined in regard to the immunological and pathological mechanisms that drive both senescence and disease progression. The use of NHPs to investigate potential therapeutic strategies to control the deleterious consequences of aging with HIV infection is also reviewed.

The Interplay between Inflammation, Coagulation and Endothelial Injury in the Early Phase of Acute Pancreatitis: Clinical Implications

Acute pancreatitis (AP) is an inflammatory disease with varied severity, ranging from mild local inflammation to severe systemic involvement resulting in substantial mortality. Early pathologic events in AP, both local and systemic, are associated with vascular derangements, including endothelial activation and injury, dysregulation of vasomotor tone, increased vascular permeability, increased leukocyte migration to tissues, and activation of coagulation. The purpose of the review was to summarize current evidence regarding the interplay between inflammation, coagulation and endothelial dysfunction in the early phase of AP. Practical aspects were emphasized: (1) we summarized available data on diagnostic usefulness of the markers of endothelial dysfunction and activated coagulation in early prediction of severe AP; (2) we reviewed in detail the results of experimental studies and clinical trials targeting coagulation-inflammation interactions in severe AP. Among laboratory tests, d-dimer and angiopoietin-2 measurements seem the most useful in early prediction of severe AP. Although most clinical trials evaluating anticoagulants in treatment of severe AP did not show benefits, they also did not show significantly increased bleeding risk. Promising results of human trials were published for low molecular weight heparin treatment. Several anticoagulants that proved beneficial in animal experiments are thus worth testing in patients.

Tissue factor expression by myeloid cells contributes to protective immune response against Mycobacterium tuberculosis infection

Tissue factor (TF) is a transmembrane glycoprotein that plays an essential role in hemostasis by activating coagulation. TF is also expressed by monocytes/macrophages as part of the innate immune response to infections. In the current study, we determined the role of TF expressed by myeloid cells during Mycobacterium tuberculosis (M. tb) infection by using mice lacking the TF gene in myeloid cells (TF(Δ) ) and human monocyte derived macrophages (MDMs). We found that during M. tb infection, a deficiency of TF in myeloid cells was associated with reduced inducible nitric oxide synthase (iNOS) expression, enhanced arginase 1 (Arg1) expression, enhanced IL-10 production and reduced apoptosis in infected macrophages, which augmented M. tb growth. Our results demonstrate that a deficiency of TF in myeloid cells promotes M2-like phenotype in M .tb infected macrophages. A deficiency in TF expression by myeloid cells was also associated with reduced fibrin deposition and increased matrix metalloproteases (MMP)-2 and MMP-9 mediated inflammation in M. tb infected lungs. Our studies demonstrate that TF expressed by myeloid cells has newly recognized abilities to polarize macrophages and to regulate M. tb growth.

Tissue Factor in Dermatitis Herpetiformis and Bullous Pemphigoid: Link between Immune and Coagulation System in Subepidermal Autoimmune Bullous Diseases

Dermatitis herpetiformis (DH) and bullous pemphigoid (BP) are skin diseases associated with eosinophilic and neutrophilic infiltrations. Although chemokines are critical for the selective accumulation and activation of various leukocyte subsets in the inflammatory process, there are few findings concerning inflammatory cells and production of coagulation factors in blistering diseases. Skin biopsies were taken from 14 patients with DH, 27 with BP, and 20 control subjects. The localization and expression of tissue factor (TF) in skin lesions and perilesional skin were studied by immunohistochemistry and confirmed by Western Blot. Moreover the plasma concentrations of TF were measured by immunoassays. D dimers, fibrinogen, and selected coagulation parameters were measured by routine methods. Expression of TF in the epidermis and in inflammatory influxed cells in dermis was detected in skin biopsies from BP patients. Examined TF expression was detected in perilesional skin of all BP patients too. The expression of TF was not observed in biopsies from healthy people and DH patients. The findings of the study show an increased expression of tissue factor in the lesional and perilesional skin of patients with bullous pemphigoid. The difference in chemokine pattern expression and variations in the cellular infiltration in BP and DH cause variable expression of TF.

Corn Silk Induced Cyclooxygenase-2 in Murine Macrophages

Stimulation of murine macrophages with corn silk induced cyclooxygenase (COX)-2 with secretion of PGE2. Expression of COX-2 was inhibited by pyrolidine dithiocarbamate (PDTC), and increased DNA binding by nuclear factor kappa B (NF-kappaB), indicating that COX-2 induction proceeds also via the NF-kappaB signaling pathway. A specific inhibitor of COX-2 decreased the expression level of inducible nitric oxide synthase (iNOS) stimulated by corn silk. PGE2 elevated the expression level of iNOS, probably via EP2 and EP4 receptors on the surface of the macrophages.

Recombinant human factor VIIa for alveolar hemorrhage following allogeneic stem cell transplantation

The mortality rate of alveolar hemorrhage (AH) after allogeneic hematopoietic stem cell transplantation is greater than 60% with supportive care and high-dose steroid therapy. We performed a retrospective cohort analysis to assess the benefits and risks of recombinant human factor VIIa (rFVIIa) as a therapeutic adjunct for AH. Between 2005 and 2012, 57 episodes of AH occurred in 37 patients. Fourteen episodes (in 14 patients) were treated with steroids alone, and 43 episodes (in 23 patients) were treated with steroids and rFVIIa. The median steroid dose was 1.9 mg/kg/d (interquartile range [IQR], 0.8 to 3.5 mg/kg/d; methylprednisolone equivalents) and did not differ statistically between the 2 groups. The median rFVIIa dose was 41 μg/kg (IQR, 39 to 62 μg/kg), and a median of 3 doses (IQR, 2 to 17) was administered per episode. Concurrent infection was diagnosed in 65% of the episodes. Patients had moderately severe hypoxia (median PaO2/FiO2, 193 [IQR, 141 to 262]); 72% required mechanical ventilation, and 42% survived to extubation. The addition of rFVIIa did not alter time to resolution of AH (P = .50), duration of mechanical ventilation (P = .89), duration of oxygen supplementation (P = .55), or hospital mortality (P = .27). Four possible thrombotic events (9% of 43 episodes) occurred with rFVIIa. rFVIIa in combination with corticosteroids did not confer clear clinical advantages compared with corticosteroids alone. In patients with AH following hematopoietic stem cell transplantation, clinical factors (ie, worsening infection, multiple organ failure, or recrudescence of primary disease) may be more important than the benefit of enhanced hemostasis from rFVIIa.

Increased mortality in systemic inflammatory response syndrome patients with high levels of coagulation factor VIIa

BACKGROUND

The tissue factor (TF)- Factor VIIa (FVIIa) complex has a pivotal role in inflammatory and coagulation responses in patients with systemic inflammatory response syndrome (SIRS) and sepsis. Because zymogen FVII (FVII) and FVIIa compete for binding to TF, their plasma levels determine if a catalytically active TF-FVIIa complex will be formed.

OBJECTIVE

To study mortality in SIRS patients as a function of FVIIa and FVII levels in plasma.

METHODS

This was a cohort study of 275 patients presenting with SIRS, aged 18 years or older and with an anticipated Intensive Care Unit (ICU) stay of at least 24 h. FVIIa was measured using a novel, quantitative assay that recognizes FVIIa, but not FVII. All-cause hospital mortality was followed over a period of 60 days.

RESULTS

The percentage of FVII measured as FVIIa was higher in non-survivors than survivors (2.8%, IQR = 1-5.5% vs. 1.5%, IQR = 0.6-3.3%; P = 0.034). High levels of FVIIa were associated with decreased 60-day cumulative survival (62% vs. 81%, P = 0.030); the opposite was observed for FVII (84% vs. 76%, P = 0.039). Patients with high-FVIIa and low-FVII levels had a three-fold increased hazard ratio (HR) compared with the patients that had low-FVIIa and high-FVII levels (HR = 3.24, 95% confidence interval [CI] = 1.41-7.36). This association persisted after adjusting for the APACHE IV score (adjusted HR = 2.75, 95% CI = 1.2-6.27).

CONCLUSIONS

SIRS patients with high-FVIIa and low-FVII on admission have an increased mortality risk, an association that is independent from the parameters included in the APACHE IV score.

Regulation of wound healing and organ fibrosis by toll-like receptors

Chronic injury often triggers maladaptive wound healing responses leading to the development of tissue fibrosis and subsequent organ malfunction. Inflammation is a key component of the wound healing process and promotes the development of organ fibrosis. Here, we review the contribution of Toll-like receptors (TLRs) to wound healing with a particular focus on their role in liver, lung, kidney, skin and myocardial fibrosis. We discuss the role of TLRs on distinct cell populations that participate in the repair process following tissue injury, and the contribution of exogenous and endogenous TLR ligands to the wound healing response. Systemic review of the literature shows that TLRs promote tissue repair and fibrosis in many settings, albeit with profound differences between organs. In particular, TLRs exert a pronounced effect on fibrosis in organs with higher exposure to bacterial TLR ligands, such as the liver. Targeting TLR signaling at the ligand or receptor level may represent a novel strategy for the prevention of maladaptive wound healing and fibrosis in chronically injured organs. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Bronchoalveolar hemostasis in lung injury and acute respiratory distress syndrome

Enhanced intrapulmonary fibrin deposition as a result of abnormal broncho-alveolar fibrin turnover is a hallmark of acute respiratory distress syndrome (ARDS), pneumonia and ventilator-induced lung injury (VILI), and is important to the pathogenesis of these conditions. The mechanisms that contribute to alveolar coagulopathy are localized tissue factor-mediated thrombin generation, impaired activity of natural coagulation inhibitors and depression of bronchoalveolar urokinase plasminogen activator-mediated fibrinolysis, caused by the increase of plasminogen activator inhibitors. There is an intense and bidirectional interaction between coagulation and inflammatory pathways in the bronchoalveolar compartment. Systemic or local administration of anticoagulant agents (including activated protein C, antithrombin and heparin) and profibrinolytic agents (such as plasminogen activators) attenuate pulmonary coagulopathy. Several preclinical studies show additional anti-inflammatory effects of these therapies in ARDS and pneumonia.

Tissue factor antisense deoxyoligonucleotide prevents monocrotaline/LPS hepatotoxicity in mice

Tissue factor (TF) is a membranous glycoprotein that functions as a receptor for coagulation factor VII/VIIa and activates the coagulation system when blood vessels or tissues are damaged. TF was upregulated in our monocrotaline (MCT)/lipopolysaccharide (LPS) hepatotoxicity model. We tested the hypothesis that TF-dependent fibrin deposition and lipid peroxidation in the form of oxidized low-density-lipoprotein (ox-LDL) accumulation contribute to liver inflammation induced by MCT/LPS in mice. In the present study, we blocked TF using antisense oligodeoxynucleotides against mouse TF (TF-ASO). TF-ASO (5.6 mg kg(-1) ) was given i.v. to ND4 male mice 30 min after administration of MCT (200 mg kg(-1) ) p.o. followed after 3.5 h by LPS i.p. (6 mg kg(-1) ). Blood alanine aminotransferase (ALT), TF, ox-LDL, platelets, hematocrit and keratinocyte-derived chemokine (KC) levels were evaluated in different treatment groups. Fibrin deposition and ox-LDL accumulation were also analyzed in the liver sections using immunofluorescent staining. The results showed that TF-ASO significantly restored blood ALT, hematocrit and KC levels, distorted after MCT/LPS co-treatment, as well as preventing the accumulation of ox-LDL and the deposition of fibrin in the liver tissues, and thereby inhibited liver injury caused by MCT/LPS. In a separate experiment, TF-ASO administration significantly prolonged animal survival. The current study demonstrates that TF is associated with MCT/LPS-induced liver injury. Administration of TF-ASO successfully prevented this type of liver injury.

Tissue factor-driven thrombin generation and inflammation in atherosclerosis

The transmembrane receptor tissue factor is a prominent protein expressed at macrophages and smooth muscle cells within human atherosclerotic lesions. While many coagulation proteins are detectable in atherosclerosis, a locally active thrombin and fibrin generating molecular machinery may be instrumental in manipulating cellular functions involved in atherogenesis. These include inflammation, angiogenesis and cell proliferation. Indeed, many experimental studies in mice show a correlation between hypercoagulability and increased atherosclerosis. In mice, the amount of atherosclerosis and/or the plaque phenotype, appear to be modifiable by specific anticoagulant interventions. While attempts to vary tissue factor level in the vasculature does not directly reduce plaque burden, the overexpression of tissue factor pathway inhibitor attenuates thrombogenicity and neo intima formation in mice. Moreover, inhibition of factor Xa or thrombin with novel selective agents, including rivaroxaban and dabigatran, inhibits inflammation associated with atherosclerosis in apoE(-/-) mice. The potential to modify a complex chronic disease like atherosclerosis with novel selective anticoagulants merits further clinical study.

Protease-activated receptor 2 signaling in inflammation

Protease-activated receptors (PARs) are G protein-coupled receptors that are activated by proteolytical cleavage of the amino-terminus and thereby act as sensors for extracellular proteases. While coagulation proteases activate PARs to regulate hemostasis, thrombosis, and cardiovascular function, PAR2 is also activated in extravascular locations by a broad array of serine proteases, including trypsin, tissue kallikreins, coagulation factors VIIa and Xa, mast cell tryptase, and transmembrane serine proteases. Administration of PAR2-specific agonistic and antagonistic peptides, as well as studies in PAR2 knockout mice, identified critical functions of PAR2 in development, inflammation, immunity, and angiogenesis. Here, we review these roles of PAR2 with an emphasis on the role of coagulation and other extracellular protease pathways that cleave PAR2 in epithelial, immune, and neuronal cells to regulate physiological and pathophysiological processes.

Tissue factor, blood coagulation, and beyond: an overview

Emerging evidence shows a broad spectrum of biological functions of tissue factor (TF). TF classical role in initiating the extrinsic blood coagulation and its direct thrombotic action in close relation to cardiovascular risks have long been established. TF overexpression/hypercoagulability often observed in many clinical conditions certainly expands its role in proinflammation, diabetes, obesity, cardiovascular diseases, angiogenesis, tumor metastasis, wound repairs, embryonic development, cell adhesion/migration, innate immunity, infection, pregnancy loss, and many others. This paper broadly covers seminal observations to discuss TF pathogenic roles in relation to diverse disease development or manifestation. Biochemically, extracellular TF signaling interfaced through protease-activated receptors (PARs) elicits cellular activation and inflammatory responses. TF diverse biological roles are associated with either coagulation-dependent or noncoagulation-mediated actions. Apparently, TF hypercoagulability refuels a coagulation-inflammation-thrombosis circuit in “autocrine” or “paracrine” fashions, which triggers a wide spectrum of pathophysiology. Accordingly, TF suppression, anticoagulation, PAR blockade, or general anti-inflammation offers an array of therapeutical benefits for easing diverse pathological conditions.

Venous thromboembolism in patients with cancer and its relationship to the coagulation cascade and vascular endothelial growth factor

Venous thromboembolism (VTE) is a well-recognized problem in malignancy. Patients with cancer who have VTE have a worse prognosis than other patients with cancer. Hypercoagulability in patients with cancer is related to malignancy itself and its treatment. These patients have multiple risk factors for thromboembolism, such as being immobilized, having central venous catheters, and receiving chemoradiation therapy. Cancer procoagulant, tissue factor, factor VIII, and thrombin have important roles in causing cancer-associated thromboembolism. Tumors require neovascularization for delivering oxygen and other nutrients. Therefore, angiogenesis facilitates tumor growth, invasion, and metastasis. New blood vessels formed by angiogenesis are thrombogenic. Hypercoagulability and tumor growth are closely related. Vascular endothelial growth factor (VEGF) is a proangiogenic factor that may also cause VTE in patients with cancer. The relationship between cancer, angiogenesis, VEGF, and thrombosis is reviewed herein. Studies are ongoing to enhance our understanding of this complex interaction.

Evidence for enhanced tissue factor expression in age-related macular degeneration

Tissue factor (TF) is the primary initiator of blood coagulation. In addition to hemostasis, TF can initiate intracellular signaling and promote inflammation and angiogenesis, the key processes underlying the pathogenesis of age-related macular degeneration (AMD). AMD, the leading cause of irreversible blindness among the elderly, involves many genetic and environmental risk factors, including oxidative stress and inflammation. In this study, TF expression was examined in human AMD tissue and in the eyes of a model of AMD, the Ccl2(-/-)/Cx3cr1(-/-) (DKO) mouse, as well as in the ARPE-19 cell line after lipopolysaccharide (LPS) and H(2)O(2) stimulation. Total RNA was extracted from tissue samples and further analyzed by real-time RT-PCR. Immunohistochemistry was performed to evaluate TF protein expression. In the human retina, a 32-fold increase of TF mRNA expression was detected in AMD macular lesions compared with normal maculae. TF protein expression was also enhanced in human AMD maculae. Similarly, TF transcript and protein expression were moderately increased in retinal lesions, neuroretinal tissue, and cultured RPE cells of DKO mice compared with age-matched wild-type mice. TF expression level correlated with age in both wild-type and DKO mice. In order to better understand how AMD might lead to enhanced TF expression, 1, 5, and 10 μg/ml LPS as well as 100 and 200 μM H(2)O(2) were used to stimulate ARPE-19 cells for 24 and 2 h, respectively. LPS treatment consistently increased TF transcript and protein expression. H(2)O(2) alone or in combination with LPS also moderately enhanced TF expression. These results indicate that upregulated TF expression may be associated with AMD, and inflammatory and oxidative stress may contribute to TF expression in AMD eyes.

Silencing of tissue factor by antisense deoxyoligonucleotide prevents monocrotaline/LPS renal injury in mice

Tissue factor (TF) is involved in monocrotaline (MCT)/lipopolysaccharide (LPS) hepatotoxicity. It is not known whether MCT/LPS can cause renal toxicity and whether TF is involved in this toxicity. Thus, the present study was undertaken to investigate the potential renal toxicity after MCT/LPS co-treatment and the involvement of TF in this toxicity. MCT was delivered to ND4 male mice (200 mg/kg) per os followed 4 h later by treatment with LPS ip (6 mg/kg) to investigate its effect on kidney. We injected TF antisense oligonucleotide (TF-AS) intravenously (i.v) in mice prior to LPS treatment, to block TF, and measured their blood urea nitrogen (BUN), creatinine (CRE), alkaline phosphatase (ALP), and potassium. In MCT/LPS co-treated group, fibrin was detected on the glomerular capillary lumina, distal tubules of renal cortex, and the necrotic tubules of renal medulla. An elevation of BUN, creatinine, and the BUN/creatinine ratio was seen in mice with MCT/LPS co-treatment, compared to animals receiving LPS or MCT alone. Simultaneously, an aggressive tubular necrosis was seen in the medullary tubules in the same group which may account for the oliguria observed in these animals. Fourfold inductions in the plasma TF level was detected at 10 h after MCT/LPS co-treatment which increased to 18-fold at 24 h. Increased blood level of leptin, interleukin-6 (IL-6) and downregulation of tubular chemokine (C-X-C motif) ligand 16 (CXCL16) are characteristic features in MCT/LPS co-treated animal. On the other hand, mice injected with TF-AS in the presence of MCT/LPS co-treatment showed no elevation of the blood BUN, creatinine, potassium, and normal levels of the proinflammatory molecules. TF-AS injection significantly prevented glomerular and tubular fibrin deposition, tubular necrosis, and improvement of the animal survivability. Renal toxicity involving TF can be prevented successfully by the use of TF-AS.

Tissue factor as a novel marker for detection of circulating cancer cells

Tissue factor (TF) is a molecular marker that is up-regulated in cancer cells and aids tumoral dissemination. Our purpose was to develop a nested RT-PCR strategy against TF for detecting blood-borne tumour cells. Our method detected TF expression in a minimum of 1.5 pg total RNA from MCF7 cells. A preliminary study in blood samples from 16 advanced breast carcinoma patients showed that 80% of patients with high TF load progressed and died, while only 18% with low TF load showed the same behaviour. Kaplan-Meier analysis confirmed worse overall survival in patients with high TF load.

Arachnoid cell involvement in the mechanism of coagulation-initiated inflammation in the subarachnoid space after subarachnoid hemorrhage

OBJECTIVE

To assess if arachnoid cells have the capability to present antigen and activate T-lymphocytes after stimulation by bloody cerebrospinal fluid (CSF), and to illuminate the mechanism of coagulation-initiated inflammation in the subarachnoid space after subarachnoid hemorrhage (SAH).

METHODS

Arachnoid cells were cultured, characterized, and examined by immunofluorescence for the basal expression of human leukocyte antigen-DR (HLA-DR). Expression of HLA-DR, after co-culturing arachnoid cells in vitro with bloody CSF, was investigated by immunofluorescence and flow cytometry (FCM). The variation of arachnoid cells' ultrastructure was observed by transmission electron microscope (TEM). Arachnoid cells were co-cultured with peripheral blood mononuclear cells (PBMCs). The content of soluble interleukin-2 receptor (sIL-2r) in culture medium was detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

(1) Arachnoid cells were successfully cultured for many passages. The immunofluorescent staining was positive for HLA-DR in over 95% of the human arachnoid cells. The punctate HLA-DR was distributed in cytoplasm and not in the karyon. (2) After co-culturing arachnoid cells in vitro with bloody CSF, numerous particles with strong fluorescence appeared in the cytoplasm on Day 6. On Day 8, the quantity of particles and fluorescent intensity were maximal. FCM showed that the percentage of HLA-DR expressing cells was (2.5+/-0.4)% at the first 5 d, increasing to (60.8+/-3.6)% on Day 7. (3) After co-culturing arachnoid cells in vitro with bloody CSF, many lysosome and secondary lysosome particles were present in the cytoplasm. Hyperplasia of rough endoplasmic reticulum and enlarged cysts were observed, with numerous phagocytizing vesicles also observed at the edge of the arachnoid cells. (4) Arachnoid cells stimulated by bloody CSF were co-cultured in vitro with PBMCs. The content of sIL-2r in the culture medium, having been maintained at around 1.30 ng/ml during the first 3 d, had increased by Day 4. The content of sIL-2r peaked 7.53 ng/ml on Day 7 and then reduced gradually.

CONCLUSIONS

(1) Basic HLA-DR expression is present in arachnoid cells. (2) After stimulation by bloody CSF, arachnoid cells have the potential to serve as antigen presenting cells (APCs) and the ability to activate T-lymphocytes, indicating that arachnoid cells are involved in the mechanism of coagulation-initiated inflammation in the subarachnoid space after SAH.

Cooperation of tissue factor cytoplasmic domain and PAR2 signaling in breast cancer development

Constitutive expression of tissue factor (TF) by cancer cells triggers local activation of the coagulation cascade and promotes breast cancer progression through cell signaling involving protease activated receptor (PAR)2. In human breast cancer, TF and PAR2 are up-regulated and TF cytoplasmic domain phosphorylation is correlated with relapse. Here we show that cancer cell PAR2 signaling promotes angiogenesis independent of PAR2 phosphorylation at the recognized β-arrestin recruitment site. Similar to PAR2(-/-) mice, TF cytoplasmic domain-deleted (TF(ΔCT)) mice have delayed spontaneous breast cancer development in the polyoma middle T model. Simultaneous deletion of PAR2 in TF(ΔCT) mice did not further delay tumor appearance, consistent with overlapping roles of TF and PAR2 in promoting the angiogenic switch in early stages of breast cancer. In advanced carcinomas, tumor-associated macrophages were reduced in TF(ΔCT) and TF(ΔCT)/PAR2(-/-) mice, and increased tumor vessel diameters of TF(ΔCT) mice were partially reversed by PAR2-deficiency, indicating that the TF cytoplasmic domain has additional roles that are interdependent with PAR2 signaling in regulating host angiogenic responses. These experiments demonstrate a crosstalk of tumor cell TF cytoplasmic domain and PAR2 signaling and provide a possible mechanism for the close correlation between TF phosphorylation and cancer recurrence of TF and PAR2-positive clinical breast cancer.

Coagulation/fibrinolysis and inflammation markers are associated with disease activity in patients with chronic urticaria

BACKGROUND

The evaluation of disease severity and activity of chronic urticaria (CU) is essential for the adequate treatment of patients. However, there is no reliable biomarker for such evaluations. Recently, markers of blood coagulation and fibrinolysis have been revealed to be elevated in severe cases of CU. In this article, we studied the coagulation/fibrinolysis and inflammation markers and their relationship to disease activity in patients with CU.

METHODS

Plasma fibrin degradation products (FDP), d-dimer and serum C-reactive protein (CRP) were measured with the assessment of disease severity and skin reaction to autologous serum in 82 patients with CU and 37 patients with acute urticaria, idiopathic angioedema (AE) or inducible types of urticaria (IU).

RESULTS

The levels of FDP in patients with CU were significantly higher than those in patients with IU, but no other differences in FDP, d-dimer and CRP were observed among patients with different types of urticaria. These markers of patients with CU were well correlated with each other and significantly associated with disease severity of CU, but not with skin reactions to autologous serum. In 37 patients with CU, levels of all these parameters reduced as their disease condition improved, while they increased when the disease became aggravated. Regarding FDP, this relationship was observed even if FDP concentrations were within normal range throughout the study.

CONCLUSIONS

The measurement of plasma FDP, d-dimer and serum CRP may be useful for the assessment of disease activity of CU.

Activated protein C action in inflammation

Activated protein C (APC) is a natural anticoagulant that plays an important role in coagulation homeostasis by inactivating the procoagulation factor Va and VIIIa. In addition to its anticoagulation functions, APC also has cytoprotective effects such as anti-inflammatory, anti-apoptotic, and endothelial barrier protection. Recently, a recombinant form of human APC (rhAPC or drotrecogin alfa activated; known commercially as 'Xigris') was approved by the US Federal Drug Administration for treatment of severe sepsis associated with a high risk of mortality. Sepsis, also known as systemic inflammatory response syndrome (SIRS) resulting from infection, is a serious medical condition in critical care patients. In sepsis, hyperactive and dysregulated inflammatory responses lead to secretion of pro- and anti-inflammatory cytokines, activation and migration of leucocytes, activation of coagulation, inhibition of fibrinolysis, and increased apoptosis. Although initial hypotheses focused on antithrombotic and profibrinolytic functions of APC in sepsis, other agents with more potent anticoagulation functions were not effective in treating severe sepsis. Furthermore, APC therapy is also associated with the risk of severe bleeding in treated patients. Therefore, the cytoprotective effects, rather than the anticoagulant effect of APC are postulated to be responsible for the therapeutic benefit of APC in the treatment of severe sepsis.

Innate immunity, coagulation and placenta-related adverse pregnancy outcomes

Maternal immunity undergoes subtle adjustment in order to tolerate the semi-allogeneic embryo and maintain the host defense against potential pathogens. Concomitantly, coagulation systems change from an anti-coagulant state to a pro-coagulant state to meet the hemostatic challenge of placentation and delivery. Innate immunity and blood coagulation systems are the first line of defense to protect a host against exogenous challenges, including alloantigens and mechanical insults, and preserve the integrity of an organism. The interactions between coagulation and immune systems have been extensively studied. Immune cells play a pivotal role in the initiation of the coagulation cascade, whereas coagulation proteases display substantial immuno-modulatory effects. Upon exogenous challenges, the immune and coagulation systems are capable of potentiating each other leading to a vicious cycle. Natural killer (NK) cells, macrophages (Mphis) and dendritic cells (DCs) are three major innate immune cells that have been demonstrated to play essential roles in early pregnancy. However, immune maladaptation and hemostatic imbalance have been suggested to be responsible for adverse pregnant outcomes, such as preeclampsia (PE), miscarriage, recurrent spontaneous abortion (RSA) and intrauterine growth restriction (IUGR). In this review, we will summarize the mutual regulation between blood coagulation and innate immune systems as well as their roles in the maintenance of normal pregnancy and in the pathogenesis of adverse pregnancy outcomes.

A review of pulmonary coagulopathy in acute lung injury, acute respiratory distress syndrome and pneumonia

Enhanced bronchoalveolar coagulation is a hallmark of many acute inflammatory lung diseases such as acute lung injury, acute respiratory distress syndrome and pneumonia. Intervention with natural anticoagulants in these diseases has therefore become a topic of interest. Recently, new data on the role of pulmonary coagulation and inflammation has become available. The aim of this review is to summarize these findings. Furthermore, the results of anticoagulant therapeutic interventions in these disorders are discussed.

Pyelonephritis during pregnancy: a cause for an acquired deficiency of protein Z

OBJECTIVE

Pyelonephritis has a more severe course during pregnancy than in the non-pregnant state. This has been attributed to the increased susceptibility of pregnant women to microbial products. An acquired protein Z deficiency has been reported when there is excessive thrombin activity. The aim of this study was to determine whether pyelonephritis during pregnancy is associated with changes in maternal plasma protein Z concentrations.

STUDY DESIGN

A cross-sectional study was conducted to compare plasma protein Z concentrations between normal pregnant women (N = 71) and pregnant women with pyelonephritis (N = 42). Protein Z concentrations were measured by enzyme-linked immunosorbent assay. Parametric and non-parametric statistics were used for analysis.

RESULTS

Patients with pyelonephritis had a significantly lower median plasma concentration of protein Z than did patients with normal pregnancies (median 2.14 microg/mL (0.4-3.4) vs. median 2.36 microg/mL (1.09-3.36); p = 0.03). There was no difference in the median plasma concentration of anti-protein Z antibodies between patients with pyelonephritis and those with normal pregnancies.

CONCLUSION

The median maternal plasma protein Z concentration was significantly lower in patients with pyelonephritis during pregnancy than in patients with normal pregnancies.

TF/FVIIa Transactivate PDGFRβ to Regulate PDGF-BB–Induced Chemotaxis in Different Cell Types

Background— We have previously reported the potentiation of PDGF-BB–induced chemotaxis of fibroblasts, vascular smooth muscle cells, and endothelial cells by FVIIa. Here we studied the role of TF/FVIIa and the induced signaling pathways in regulation of chemotaxis of human monocytes, fibroblasts, and porcine aorta endothelial cells.

Methods and Results— Human monocytes were obtained by using Ficoll-Paque gradient and the MACS system (for highly purified population), fibroblasts and PAE cells have been characterized previously. Inhibitors of selected signaling intermediates were used, and the effect of TF/FVIIa on the migratory response of all cells to chemotactic agents was analyzed. The induced signaling was studied by immunoprecipitation and Western blotting. TF/FVIIa complex selectively enhanced PDGF-BB–induced chemotaxis in a Src-family, PLC, and PAR-2–dependent manner. Using PAE cells we identified c-Src and c-Yes as the Src-family members activated by TF/FVIIa. We report for the first time the PAR-2 and Src family-dependent transactivation of PDGFRβ by TF/FVIIa involving phosphorylation of a subset of PDGFRβ tyrosines.

Conclusions— The described transactivation is a likely mechanism of TF/FVIIa-mediated regulation of PDGF-BB–induced chemotaxis. Similar behavior of 3 principally different cell types in our experimental setup may reflect a general function of TF in regulation of cell migration.