Tissue factor mediates inflammation

Carbon tetrachloride-induced liver injury in mice is tissue factor dependent

Tissue factor (TF) is a membranous glycoprotein that activates the coagulation system when blood vessels or tissues are damaged. TF was up-regulated in monocrotaline (MCT)/lipopolysaccharide (LPS) hepatotoxicity model. The present study aimed to test the hypothesis that TF-dependent fibrin deposition occurs in liver toxicity induced by CCl4 in mice. Pericentral deposition of TF and fibrin is induced after CCl4-induced liver toxicity. The toxicity was evaluated by determination of serum activities of ALT, AST and ALP as well as GSH content and histopathological changes. The results showed that injection of mice with TF-antisense deoxyoligonucleotide (TF-AS) prevented the accumulation of TF and fibrin in the hepatic tissues. Furthermore, it significantly restored blood biochemical parameters, GSH content and distorted histopathological features caused by CCl4. The current study demonstrates that TF activation is associated with CCl4-induced liver injury. Furthermore, administration of TF-AS successfully prevented this type of liver injury.

Systemic inflammation in xenograft recipients precedes activation of coagulation

BACKGROUND

Dysregulation of coagulation is considered a major barrier against successful pig organ xenotransplantation in non-human primates. Inflammation is known to promote activation of coagulation. The role of pro-inflammatory factors as well as the relationship between inflammation and activation of coagulation in xenograft recipients is poorly understood.

METHODS

Baboons received kidney (n=3), heart (n=4), or artery patch (n=8) xenografts from α1,3-galactosyltransferase gene-knockout (GTKO) pigs or GTKO pigs additionally transgenic for human complement-regulatory protein CD46 (GTKO/CD46). Immunosuppression (IS) was based on either CTLA4Ig or anti-CD154 costimulation blockade. Three artery patch recipients did not receive IS. Pro-inflammatory cytokines, chemokines, and coagulation parameters were evaluated in the circulation after transplantation. In artery patch recipients, monocytes and dendritic cells (DC) were monitored in peripheral blood. Expression of tissue factor (TF) and CD40 on monocytes and DC were assessed by flow cytometry. C-reactive protein (C-RP) levels in the blood and C-RP deposition in xenografts as well as native organs were evaluated. Baboon and pig C-RP mRNA in heart and kidney xenografts were evaluated.

RESULTS

In heart and kidney xenograft recipients, the levels of INFγ, TNF-α, IL-12, and IL-8 were not significantly higher after transplantation. However, MCP-1 and IL-6 levels were significantly higher after transplantation, particularly in kidney recipients. Elevated C-RP levels preceded activation of coagulation in heart and kidney recipients, where high levels of C-RP were maintained until the time of euthanasia in both heart and kidney recipients. In artery patch recipients, INFγ, TNF-α, IL-12, IL-8, and MCP-1 were elevated with no IS, while IL-6 was not. With IS, INFγ, TNF-α, IL-12, IL-8, and MCP-1 were reduced, but IL-6 was elevated. Elevated IL-6 levels were observed as early as 2 weeks in artery patch recipients. While IS was associated with reduced thrombin activation, fibrinogen and C-RP levels were increased when IS was given. There was a significant positive correlation between C-RP, IL-6, and fibrinogen levels. Additionally, absolute numbers of monocytes were significantly increased when IS was given, but not without IS. This was associated with increased CD40 and TF expression on CD14+ monocytes and lineage(neg) CD11c+ DC, with increased differentiation of the pro-inflammatory CD14+ CD11c+ monocyte population. At the time of euthanasia, C-RP deposition in kidney and heart xenografts, C-RP positive cells in artery patch xenograft and native lungs were detected. Finally, high levels of both pig and baboon C-RP mRNA were detected in heart and kidney xenografts.

CONCLUSIONS

Inflammatory responses precede activation of coagulation after organ xenotransplantation. Early upregulation of C-RP and IL-6 levels may amplify activation of coagulation through upregulation of TF on innate immune cells. Prevention of systemic inflammation in xenograft recipients (SIXR) may be required to prevent dysregulation of coagulation and avoid excessive IS after xenotransplantation.

Chronic urticaria and coagulation: pathophysiological and clinical aspects

Chronic urticaria (CU) is a widespread skin disease, characterized by the recurrence of transient wheals and itch for more than 6 weeks. Besides autoimmune mechanisms, coagulation factors, in particular tissue factor and thrombin, might also participate in the disease pathophysiology. Tissue factor expressed by eosinophils can induce activation of blood coagulation generating thrombin which in turn can increase vascular permeability both directly, acting on endothelial cells, and indirectly, inducing degranulation of mast cells with release of histamine, as demonstrated in experimental models. D-dimer, a fibrin degradation product, generated following activation of the coagulation cascade and fibrinolysis, has been found to be increased during urticaria exacerbations; moreover, it has been proposed as a biomarker of severity and resistance to H1-antihistamines in CU patients. The possible role of coagulation in CU is also supported by case reports, case series and a small controlled study showing the efficacy of anticoagulant therapy in this disease. The purpose of this review was to summarize the available data on the possible contribution of coagulation to the pathophysiology of CU focusing on clinical aspects and possible future therapeutic developments.

Air pollution upregulates endothelial cell procoagulant activity via ultrafine particle-induced oxidant signaling and tissue factor expression

Air pollution exposure is associated with cardiovascular events triggered by clot formation. Endothelial activation and initiation of coagulation are pathophysiological mechanisms that could link inhaled air pollutants to vascular events. Here we investigated the underlying mechanisms of increased endothelial cell procoagulant activity following exposure to soluble components of ultrafine particles (soluble UF). Human coronary artery endothelial cells (HCAEC) were exposed to soluble UF and assessed for their ability to trigger procoagulant activity in platelet-free plasma. Exposed HCAEC triggered earlier thrombin generation and faster fibrin clot formation, which was abolished by an anti-tissue factor (TF) antibody, indicating TF-dependent effects. Soluble UF exposure increased TF mRNA expression without compensatory increases in key anticoagulant proteins. To identify early events that regulate TF expression, we measured endothelial H2O2 production following soluble UF exposure and identified the enzymatic source. Soluble UF exposure increased endothelial H2O2 production, and antioxidants attenuated UF-induced upregulation of TF, linking the procoagulant responses to reactive oxygen species (ROS) formation. Chemical inhibitors and RNA silencing showed that NOX-4, an important endothelial source of H2O2, was involved in UF-induced upregulation of TF mRNA. These data indicate that soluble UF exposure induces endothelial cell procoagulant activity, which involves de novo TF synthesis, ROS production, and the NOX-4 enzyme. These findings provide mechanistic insight into the adverse cardiovascular effects associated with air pollution exposure.

The coagulation system and its function in early immune defense

Blood coagulation has a Janus-faced role in infectious diseases. When systemically activated, it can cause serious complications associated with high morbidity and mortality. However, coagulation is also part of the innate immune system and its local activation has been found to play an important role in the early host response to infection. Though the latter aspect has been less investigated, phylogenetic studies have shown that many factors involved in coagulation have ancestral origins which are often combined with anti-microbial features. This review gives a general overview about the most recent advances in this area of research also referred to as immunothrombosis.

Air pollution and gene-specific methylation in the Normative Aging Study: association, effect modification, and mediation analysis

The mechanisms by which air pollution has multiple systemic effects in humans are not fully elucidated, but appear to include inflammation and thrombosis. This study examines whether concentrations of ozone and components of fine particle mass are associated with changes in methylation on tissue factor (F3), interferon gamma (IFN-γ), interleukin 6 (IL-6), toll-like receptor 2 (TLR-2), and intercellular adhesion molecule 1 (ICAM-1). We investigated associations between air pollution exposure and gene-specific methylation in 777 elderly men participating in the Normative Aging Study (1999-2009). We repeatedly measured methylation at multiple CpG sites within each gene's promoter region and calculated the mean of the position-specific measurements. We examined intermediate-term associations between primary and secondary air pollutants and mean methylation and methylation at each position with distributed-lag models. Increase in air pollutants concentrations was significantly associated with F3, ICAM-1, and TLR-2 hypomethylation, and IFN-γ and IL-6 hypermethylation. An interquartile range increase in black carbon concentration averaged over the four weeks prior to assessment was associated with a 12% reduction in F3 methylation (95% CI: -17% to -6%). For some genes, the change in methylation was observed only at specific locations within the promoter region. DNA methylation may reflect biological impact of air pollution. We found some significant mediated effects of black carbon on fibrinogen through a decrease in F3 methylation, and of sulfate and ozone on ICAM-1 protein through a decrease in ICAM-1 methylation.

Haemostasis in chronic kidney disease

The coagulation system has gained much interest again as new anticoagulatory substances have been introduced into clinical practice. Especially patients with renal failure are likely candidates for such a therapy as they often experience significant comorbidity including cardiovascular diseases that require anticoagulation. Patients with renal failure on new anticoagulants have experienced excessive bleeding which can be related to a changed pharmacokinetic profile of the compounds. However, the coagulation system itself, even without any interference with coagulation modifying drugs, is already profoundly changed during renal failure. Coagulation disorders with either episodes of severe bleeding or thrombosis represent an important cause for the morbidity and mortality of such patients. The underlying reasons for these coagulation disorders involve the changed interaction of different components of the coagulation system such as the coagulation cascade, the platelets and the vessel wall in the metabolic conditions of renal failure. Recent work provides evidence that new factors such as microparticles (MPs) can influence the coagulation system in patients with renal insufficiency through their potent procoagulatory effects. Interestingly, MPs may also contain microRNAs thus inhibiting the function of platelets, resulting in bleeding episodes. This review comprises the findings on the complex pathophysiology of coagulation disorders including new factors such as MPs and microRNAs in patients with renal insufficiency.

Chemokines and Their Receptors Are Key Players in the Orchestra That Regulates Wound Healing

SIGNIFICANCE

Normal wound healing progresses through a series of overlapping phases, all of which are coordinated and regulated by a variety of molecules, including chemokines. Because these regulatory molecules play roles during the various stages of healing, alterations in their presence or function can lead to dysregulation of the wound-healing process, potentially leading to the development of chronic, nonhealing wounds.

RECENT ADVANCES

A discovery that chemokines participate in a variety of disease conditions has propelled the study of these proteins to a level that potentially could lead to new avenues to treat disease. Their small size, exposed termini, and the fact that their only modifications are two disulfide bonds make them excellent targets for manipulation. In addition, because they bind to G-protein-coupled receptors (GPCRs), they are highly amenable to pharmacological modulation.

CRITICAL ISSUES

Chemokines are multifunctional, and in many situations, their functions are highly dependent on the microenvironment. Moreover, each specific chemokine can bind to several GPCRs to stimulate the function, and both can function as monomers, homodimers, heterodimers, and even oligomers. Activation of one receptor by any single chemokine can lead to desensitization of other chemokine receptors, or even other GPCRs in the same cell, with implications for how these proteins or their receptors could be used to manipulate function.

FUTURE DIRECTIONS

Investment in better understanding of the functions of chemokines and their receptors in a local context can reveal new ways for therapeutic intervention. Understanding how different chemokines can activate the same receptor and vice versa could identify new possibilities for drug development based on their heterotypic interactions.

Direct inhibition of factor VIIa by TFPI and TFPI constructs

BACKGROUND

Tissue factor pathway inhibitor (TFPI) is a multi-Kunitz domain protease inhibitor that down-regulates the extrinsic coagulation pathway by inhibiting FXa and FVIIa.

OBJECTIVES

To investigate the role of the three Kunitz domains (KDs) of TFPI in FVIIa inhibition using full-length TFPI (TFPIfl ) and truncated TFPI constructs.

METHODS

Inhibition of FVIIa with/without relipidated tissue factor (TF) or soluble TF (sTF) by TFPIfl /TFPI constructs was quantified with a FVIIa-specific chromogenic substrate.

RESULTS AND CONCLUSIONS

TFPIfl inhibited TF-FVIIa via a monophasic reaction, which is rather slow at low TFPIfl concentrations (t½  ≈ 5 min at 2 nm TFPI) and has a Ki of 4.6 nm. In the presence of sTF and without TF, TFPIfl was a poor FVIIa inhibitor, with Ki values of 122 nm and 1118 nm, respectively. This indicates that phospholipids and TF significantly contribute to FVIIa inhibition by TFPIfl . TFPI constructs without the KD3-c-terminus (TFPI1-150 and KD1-KD2) were 7-10-fold less effective than TFPIfl in inhibiting TF-FVIIa and sTF-FVIIa, indicating that the KD3-C-terminus significantly contributes to direct inhibition of FVIIa by TFPI. Compared with KD1-KD2, KD1 was a poor TF-FVIIa inhibitor (Ki =434 nm), which shows that the KD2 domain of TFPI also contributes to FVIIa inhibition. Protein S stimulated TF-FVIIa inhibition by TFPIfl (Ki =0.7 nm). In the presence of FXa, a tight quaternary TF-FVIIa-TFPI-FXa complex is formed with TFPIfl , TFPI1-150 and KD1-KD2, with Ki values of < 0.15 nm, 0.5 nm and 0.8 nm, respectively, indicating the KD3-C-terminus is not a prerequisite for quaternary complex formation. Phospholipids and the Gla-domain of FXa are required for quaternary complex formation.

Chemical and microbial semi-synthesis of tetrahydroprotoberberines as inhibitors on tissue factor procoagulant activity

To discover new inhibitors on tissue factor procoagulant activity, 21 tetrahydroprotoberberines were screened on the model of human THP-1 cells stimulated by lipopolysaccharide. Among these tetrahydroprotoberberines, several unique compounds were synthesized through microbial transformation: compound 6 (l-corydalmine) was obtained through regio-selective demethylation by Streptomyces griseus ATCC 13273, whereas compounds 4a, 4b, 5h, and 5i were microbial glycosylation products by Gliocladium deliquescens NRRL1086. The bioassay results showed that compounds 3 (tetrahydroberberine), 10 (tetrahydroberberrubine), and 5f (cinnamyl ester of 5) and 5i (glycosidic product of 5), exhibited the most potential effects, with IC(50) values of 8.35, 6.75, 3.75, and 8.79 nM, respectively. The preliminary structure and activity relationship analysis revealed that the 2,3-methylenedioxy group of the A ring was essential for the strong inhibitory effects, and the R configuration of the chiral center C-14 showed higher activity than S-form products. The formation of fatty acid or aromatic acid esters of compound 5, except the cinnamyl esters, would weaken its effects. It is also interesting to note that the glycosylation of tetrahydroprotoberberines will maintain and even enhance the inhibitory effects. Because of the importance of glycochemistry in new drug discovery and development, this deserves further exploration and may provide some guide on the semi-synthesis of tetrahydroprotoberberines as tissue factor pathway inhibitors. Our findings also provide some potential leading compounds for tissue factor-related diseases, such as cancer and cardiovascular diseases.

Mycobacterium tuberculosis infection and tissue factor expression in macrophages

A number of earlier studies reported the occurrence of thrombotic complications, particularly disseminated intravascular coagulation and deep vein thrombosis, in tuberculosis (TB) patients. The aberrant expression of tissue factor (TF), the primary activator of coagulation cascade, is known to be responsible for thrombotic disorders in many diseases including bacterial infections. Further, expression of TF by cells of the monocyte/macrophage lineage is also shown to contribute to the development and progression of local and systemic inflammatory reactions. In the present study, we have investigated whether Mycobacterium tuberculosis (Mtb) infection induces TF expression in macrophages, and various host and pathogenic factors responsible for TF expression. We have tested the effect of live virulent Mtb H37Rv, gamma-irradiated Mtb H37Rv (γ-Mtb) and various components derived from Mtb H37Rv on TF expression in macrophages. The data presented in the manuscript show that both live virulent Mtb and γ-Mtb treatments markedly increased TF activity in macrophages, predominantly in the CD14⁺ macrophages. Detailed studies using γ-Mtb showed that the increased TF activity in macrophages following Mtb treatment is the result of TF transcriptional activation. The signaling pathways of TF induction by Mtb appears to be distinct from that of LPS-induced TF expression. Mtb-mediated TF expression is dependent on cooperation of CD14/TLR2/TLR4 and probably yet another unknown receptor/cofactor. Mtb cell wall core components, mycolyl arabinogalactan peptidoglycan (mAGP), phosphatidylinositol mannoside-6 (PIM6) and lipomannan (LM) were identified as factors responsible for induction of TF in the order of mAGP>PIM6>LM. A direct contact between bacteria and macrophage and not Mtb-released soluble factors is critical for TF induction by Mtb. In summary, our data show that Mtb induces TF expression in macrophages and Mtb signaling pathways that elicit TF induction require cooperation of multiple receptors, co-receptors/co-factors including Toll-like receptors. The importance of TF in granuloma formation and containment of Mtb is discussed.

Gene promoter methylation is associated with lung function in the elderly: the Normative Aging Study

Lung function is a strong predictor of mortality. While inflammatory markers have been associated with lung function decrease, pathways are still poorly understood and epigenetic changes may participate in lung function decline mechanisms. We studied the cross-sectional association between DNA methylation in nine inflammatory genes and lung function in a cohort of 756 elderly men living in the metropolitan area of Boston. Participants donated a blood sample for DNA methylation analysis and underwent spirometry at each visit every 3 to 5 y from 1999-2006. We used separate multivariate mixed effects regression models to study the association between each lung function measurement and DNA methylation within each gene. Decreased CRAT, F3 and TLR2 methylation was significantly associated with lower lung function. One interquartile range (IQR) decrease in DNA methylation was associated with lower forced vital capacity (FVC) and forced expiratory volume in one second (FEV 1), respectively by 2.94% (p < 10 (-4)) and 2.47% (p < 10 (-3)) for F3, and by 2.10% (p < 10 (-2)) and 2.42% (p < 10 (-3)) for TLR2. Decreased IFNγ and IL6 methylation was significantly associated with better lung function. One IQR decrease in DNA methylation was associated with higher FEV 1 by 1.75% (p = 0.02) and 1.67% (p = 0.05) for IFNγ and IL6, respectively. These data demonstrate that DNA methylation may be part of the biological processes underlying the lung function decline and that IFNγ and IL6 may have ambivalent roles through activation of negative feedback.

Markers of autoreactivity, coagulation and angiogenesis in patients with nonallergic asthma

BACKGROUND

Patients with nonallergic asthma frequently show autoreactivity as do subjects with chronic urticaria (CU). Activation of the coagulation cascade and hyper-expression of vascular endothelial growth factor (VEGF) were recently found in CU, and there is sparse evidence that the same may occur in asthma.

OBJECTIVE

To investigate autoreactivity, activation of the coagulation cascade, and expression of VEGF in patients with nonallergic asthma.

METHODS

Twenty-one adults with nonallergic asthma underwent autologous plasma skin test (APST) and the measurement of plasma levels of the prothrombin fragment F1+2, D-dimer, VEGF, and the inflammatory marker C-reactive protein (CRP). Twenty-one healthy sex- and age-matched subjects served as normal controls.

RESULTS

The APST scored positive in 19 of 21 (90%) patients vs 0 controls. Mean fragment F1+2 plasma levels were significantly higher in patients with asthma (267 ± 243 pM) than in controls (150 ± 51 pM; P = 0.0001). Similarly, plasma levels of both D-dimer and VEGF were significantly higher in patients than in controls (D-dimer: 2364 ± 1467 vs 1301 ± 525 pM; P = 0.0001; VEGF: 1721 ± 2566 vs 76 ± 375 fM; P = 0.0001). A trend toward increased levels of F1+2, D-dimer, VEGF, and CRP was found in patients with a more severe disease according to GINA classification.

CONCLUSION

Nonallergic asthma is characterized by autoreactivity as well as increased coagulation and angiogenesis markers, which are known to enhance vascular permeability. The presence of circulating vasoactive factors may be relevant to understand the disease pathophysiology and to detect novel therapeutic strategies in nonallergic asthma.

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.

The missing link between atherosclerosis, inflammation and thrombosis: is it tissue factor?

Acute thrombus formation on disrupted atherosclerotic plaques plays a key role during the onset of acute coronary syndromes. Lesion disruption facilitates the interaction between circulating blood and prothrombotic substances, such as tissue factor (TF) present within the atherosclerotic lesion. For a long period of time, vessel-wall TF has been considered the major determinant of thrombosis. However, this old dogma has been recently changed owing to the discovery of a different pool of TF that circulates in flowing blood (blood-borne TF). Several studies have shown that blood-borne TF circulates in different pools that are associated with selected blood cells, such as monocytes, granulocytes and platelets in cell-derived microparticles, and as a soluble protein generated by alternative splicing of its full-length mRNA. Recent studies have identified a hypercoagulable state associated with an increased circulating TF activity, leading to the concept of 'vulnerable blood'. Part of the blood-borne TF circulates in an 'inactive' form and it is required to be 'activated' to exert its thrombogenic potential. Certain pathological conditions, such as smoking, hyperlipidemia and diabetes, show a higher incidence of thrombotic complications. These conditions are also characterized by the presence of high levels of circulating TF activity. Recent evidence may also suggest that an increased circulating TF activity may potentiate the initial thrombogenic stimulus represented by vessel wall-associated TF, leading to the formation of larger and/or more stable thrombus, and thus more severe acute coronary syndromes. It has been reported that inflammation increases TF expression and activity by different cell types. On the other hand, TF upregulation may facilitate inflammation by enhancing intravascular fibrin deposition, formation of proinflammatory fragments of fibrin, and by generating coagulation proteases, including FVIIa, FXa and thrombin, that activate protease-activated receptors. Furthermore, the biology of TF is know known to be more complex than previously thought by the demonstration that this protein, apart from its known effects on blood coagulation, can also function as a signaling receptor.

Expression of coagulation-related protein genes during LPS-induced preterm delivery in the pregnant mouse

Preterm delivery (PTD) has been associated with inflammation along with activation of the coagulation pathway. These studies sought to characterize the expression of several coagulation pathway genes including plasminogen activator inhibitor 1 (PAI-1), tissue factor (TF), protease-activated receptor 1 (Par1), protease-activated receptor 2 (Par2), fibrinogen-like protein 2 (Fgl2), and thrombomodulin (TM) during lipopolysaccharide (LPS)-induced PTD in day 15 pregnant CD-1 mice. Western blot studies confirmed protein expression for PAI-1, Par1, Par2, Fgl2, and TM in the mouse uterus. Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) confirmed increased PAI-1 messenger RNA (mRNA) in the uteri, lung, kidney, and liver tissues at 2 to 6 hours after LPS injection. In contrast, TF expression significantly decreased by 12 hours in uterine tissue; whereas, its expression was unchanged in the other maternal tissues. The uterine mRNA for Par1, Par2, Fgl2, and TM remained stable. In summary, these studies have confirmed expression of coagulation pathway genes within the pregnant uterus; some of which are modulated during LPS-induced PTD.

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.

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

BACKGROUND

Tissue factor (TF) is expressed in 2 isoforms: membrane-bound "full length" (fl)TF and soluble alternatively spliced (as)TF. flTF is the major thrombogenic form of TF. Although the function of asTF is poorly understood, it was suggested that asTF contributes to tumor-associated growth and angiogenesis. In the heart of a developing embryo, asTF is expressed much later compared to flTF, but in adult heart, asTF exhibits a distribution pattern similar to that of flTF. Thus, it is possible that asTF may play a role in heart development via pro-angiogenic signaling. The purpose of the present study was to examine the effects of murine asTF overexpression in murine cardiomyocyte-like HL-1 cells on their pro-angiogenic potential, the chemotaxis of monocytic cells, and the expression of fibroblast growth factor-2 (FGF2), cysteine-rich 61 (Cyr61), and vascular endothelial growth factor (VEGF).

METHODS AND RESULTS

Expression of FGF2, Cyr61 and VEGF was assessed on reverse transcription-polymerase chain reaction and western blot. Cell migration, proliferation, and endothelial tube formation assays were carried out. It was found that overexpression of murine asTF in HL-1 cells increases their proliferation and pro-angiogenic properties. The supernatant of murine asTF-overexpressing HL-1 cells induces the chemotaxis of monocytic cells.

CONCLUSIONS

Overexpression of murine asTF in murine cardiomyocytic cells increases their proliferation, monocyte migration, and pro-angiogenic properties -possibly- mediated by the induction of the pro-migratory and pro-angiogenic factors FGF2, Cyr61 and VEGF. Thus, we propose that murine asTF may serve as a migration- and angiogenesis-promoting factor.

Activation of blood coagulation in autoimmune skin disorders

The immune system and blood coagulation are simultaneously activated in several inflammatory systemic disorders, such as lupus erythematosus, rheumatoid arthritis and inflammatory bowel diseases. Proinflammatory cytokines, such as IL-6 and TNF-alpha, induce the expression of tissue factor, the main initiator of blood coagulation. Activated proteases of coagulation in turn act on protease-activated receptors, inducing the expression of various proinflammatory cytokines. This cross-talk between inflammation and coagulation amplifies and maintains the activation of both systems. This review focuses on three skin disorders: chronic urticaria (CU), which is considered autoimmune in approximately 50% of cases, bullous pemphigoid (BP), which is the prototype of autoimmune blistering disease, and psoriasis, which is an immune-mediated dermatitis. In CU, the activation of coagulation, which is due to the involvement of eosinophils and tissue factor pathways with the generation of thrombin, has local implications by increasing dermal vascular permeability. Preliminary data indicate that anticoagulant treatment with heparin and warfarin may be effective in reducing the symptoms of this disorder. In BP, the activation of coagulation seems to have both local and systemic implications. Locally, eosinophils and thrombin participate in bulla formation and tissue damage; systemically, the activation of coagulation may explain the increased thrombotic risk observed in these patients. In psoriasis, the activation of coagulation seems to be mainly systemic, potentially contributing to the increased cardiovascular risk associated with this disease.

Skin autoimmunity and blood coagulation

Evidence exists that the immune and coagulation systems are simultaneously activated in some systemic autoimmune disorders. Although proinflammatory mediators induce tissue factor (TF) expression, the main initiator of blood coagulation, activated proteases of coagulation may act on protease-activated receptors (PAR) triggering inflammation. Such a cross-talk amplifies and maintains the activation of both systems. This review focuses on the involvement of immune and coagulation system in two skin disorders as chronic urticaria (CU), autoimmune in about 45% of cases, and bullous pemphigoid (BP), the prototype of autoimmune blistering diseases. Several investigators demonstrated the activation of coagulation in CU through the involvement of eosinophils, of TF pathway with thrombin generation and increased vascular permeability. Preliminary data indicate that anticoagulant treatment with heparin and warfarin may be effective in reducing the symptoms of this disorder. The activation of coagulation seems to display local and systemic implications in BP. Eosinophils' recruitment and thrombin generation locally contribute to the bulla formation and tissue damage. The systemic activation of coagulation may explain the increased thrombotic risk observed in these patients. Taken together, these data provide the rationale for proposing clinical trials on the anticoagulant treatment in both CU and BP patients.

Stachydrine, a major constituent of the Chinese herb leonurus heterophyllus sweet, ameliorates human umbilical vein endothelial cells injury induced by anoxia-reoxygenation

Stachydrine is a major constituent of Chinese herb leonurus heterophyllus sweet, which is used in clinics to promote blood circulation and dispel blood stasis. Our study aimed to investigate the role of stachydrine in human umbilical vein endothelial cells (HUVECs) injury induced by anoxia-reoxygenation. Cultured HUVECs were divided randomly into control group, anoxia-reoxygenation (A/R) group and 4 A/R+stachydrine groups. HUVECs in the control group were exposed to normoxia for 5 hours, while in all A/R groups, HUVECs underwent 3 hours anoxia followed by 2 hours reoxygenation, and HUVECs in the 4 A/R+stachydrine groups were treated with 10(-8) M, 10(-7) M, 10(-6) M and 10(-5) M (final concentration) of stachydrine respectively. After anoxia-reoxygenation, tissue factor (TF) was over-expressed, cell viability and the concentrations of SOD, GSH-PX and NO were declined, while LDH, MDA and ET-1 were over-produced (p < 0.05 to 0.001 vs. the control group). However, in stachydrine treated groups, TF expression was inhibited at both mRNA and protein levels, while the declined cell viability and SOD, GSH-PX, NO as well as the enhanced LDH, MDA and ET-1 levels occurred during anoxia-reoxygenation were ameliorated and reversed effectively (p < 0.05 to 0.01 versus A/R group). Consequently, our findings indicate that TF plays an important role in the development of anoxia-reoxygenation injury of HUVECs, stachydrine ameliorates HUVECs injury induced by anoxia-reoxygenation and its putative mechanisms are related to inhibition of TF expression.

Differential expression of protease-activated receptors in monocytes from patients with primary antiphospholipid syndrome

OBJECTIVE

To investigate the expression of protease-activated receptors (PARs), their potential regulation by anticardiolipin antibodies (aCL), and their association with the expression of other molecules relevant to thrombosis in monocytes obtained from 62 patients with primary antiphospholipid syndrome (APS).

METHODS

Monocytes were isolated from peripheral blood mononuclear cells by magnetic depletion of nonmonocytes. Expression of tissue factor (TF) and PARs 1-4 genes was measured by quantitative real-time reverse transcription-polymerase chain reaction. Cell surface TF and PARs 1-4 expression was analyzed by flow cytometry. For in vitro studies, purified normal monocytes were incubated with purified APS patient IgG, normal human serum IgG, or lipopolysaccharide, in the presence or absence of specific monoclonal antibodies anti-PAR-1 (ATAP2) or anti-PAR-2 (SAM11) to test the effect of blocking the active site of PAR-1 or PAR-2.

RESULTS

Analysis of both mRNA and protein for the 4 PARs revealed significantly increased expression of PAR-2 as compared with the control groups. PAR-1 was significantly overexpressed in APS patients with thrombosis and in the control patients with thrombosis but without APS. PAR-3 expression was not significantly altered. PAR-4 expression was absent in all groups analyzed. In addition, we demonstrated a correlation between the levels of PAR-2 and the titers of IgG aCL, as well as parallel behavior of TF and PAR-2 expression. In vitro, IgG from APS patients significantly increased monocyte expression of PAR-1 and PAR-2. Inhibition studies suggested that there was direct cross-talk between TF and PAR-2, such that inhibition of PAR-2 prevented the aCL-induced expression of TF.

CONCLUSION

These results provide the first demonstration of increased expression of PARs in monocytes from patients with APS. Thus, PAR antagonists might have therapeutic potential as antithrombotic agents in APS.

Time-response relationship of nano and micro particle induced lung inflammation. Quartz as reference compound

An increasing number of engineered particles, including nanoparticles, are being manufactured, increasing the need for simple low-dose toxicological screening methods. This study aimed to investigate the kinetics of biomarkers related to acute and sub-chronic particle-induced lung inflammation of quartz. Mice were intratracheal instilled with 50 µg of microsized or nanosized quartz. Acute inflammation was assessed 1, 2, 4, 8, 16 or 48 hours post exposure, whereas sub-chronic inflammation was investigated 3 months after exposure. Markers of acute inflammation in the bronchoalveolar lavage fluid (BALF) were neutrophils (PMN), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, macrophage inflammatory protein-2 (MIP-2), keratinocyte derived chemokine (KC) and total protein, which were all close to maximum 16 hours post instillation. No major differences were seen in the time-response profiles of nano- and micro-sized particles. The potency of the two samples cannot be compared; during the milling process, a substantial part of the quartz was converted to amorphous silica and contaminated with corundum. For screening, BALF PMN, either TNF-α or IL-1β at 16 hours post instillation may be useful. At 3 months post instillation, KC, PMN and macrophages were elevated. Histology showed no interstitial inflammation three months post instillation. For screening of sub-chronic effects, KC, PMN, macrophages and histopathology is considered sufficient.

A functional polymorphism (-603A --> G) in the tissue factor gene promoter is associated with adult-onset asthma

Tissue factor (TF) is important for initiation of coagulation and for the increased thrombin activity observed at sites of inflammation. Thrombin activity is induced by allergen challenge in asthmatic airways and is involved in the pathogenesis of asthma. A -603A --> G polymorphism (rs1361600) in the promoter region of the TF gene has been associated with serum TF levels and with the development of cardiovascular diseases. The aim of this study was to determine whether the functional -603A --> G polymorphism has genetic influences on the development of asthma. Case-control analysis was performed of the association between six common single-nucleotide polymorphisms (SNPs), including the -603A --> G polymorphism, at the TF gene, and the development of asthma, using two unrelated Japanese populations. In the primary population (n=826), the GG genotype at the -603A --> G polymorphism was associated with adult-onset asthma (onset at >or=21 years of age) (odds ratio (OR) 2.886, P=0.0231). A second population showed a similar tendency (n=1654, OR 1.602, P=0.064). Transcriptional activity of promoters with -603A --> G genotypes were examined using luciferase promoter assays. The -603G allele was associated with higher promoter activity (P<0.05). The association between the functional polymorphism (-603A --> G) in the TF gene promoter and adult-onset asthma indicates that TF is a candidate gene contributing to asthma susceptibility.

Potential mechanisms underlying the acute lung dysfunction and bacterial extrapulmonary dissemination during Burkholderia cenocepacia respiratory infection

Background

Burkholderia cenocepacia, an opportunistic pathogen that causes lung infections in cystic fibrosis (CF) patients, is associated with rapid and usually fatal lung deterioration due to necrotizing pneumonia and sepsis, a condition known as cepacia syndrome. The key bacterial determinants associated with this poor clinical outcome in CF patients are not clear. In this study, the cytotoxicity and procoagulant activity of B. cenocepacia from the ET-12 lineage, that has been linked to the cepacia syndrome, and four clinical isolates recovered from CF patients with mild clinical courses were analysed in both in vitro and in vivo assays.

Methods

B. cenocepacia-infected BEAS-2B epithelial respiratory cells were used to investigate the bacterial cytotoxicity assessed by the flow cytometric detection of cell staining with propidium iodide. Bacteria-induced procoagulant activity in cell cultures was assessed by a colorimetric assay and by the flow cytometric detection of tissue factor (TF)-bearing microparticles in cell culture supernatants. Bronchoalveolar lavage fluids (BALF) from intratracheally infected mice were assessed for bacterial proinflammatory and procoagulant activities as well as for bacterial cytotoxicity, by the detection of released lactate dehydrogenase.

Results

ET-12 was significantly more cytotoxic to cell cultures but clinical isolates Cl-2, Cl-3 and Cl-4 exhibited also a cytotoxic profile. ET-12 and CI-2 were similarly able to generate a TF-dependent procoagulant environment in cell culture supernatant and to enhance the release of TF-bearing microparticles from infected cells. In the in vivo assay, all bacterial isolates disseminated from the mice lungs, but Cl-2 and Cl-4 exhibited the highest rates of recovery from mice livers. Interestingly, Cl-2 and Cl-4, together with ET-12, exhibited the highest cytotoxicity. All bacteria were similarly capable of generating a procoagulant and inflammatory environment in animal lungs.

Conclusion

B. cenocepacia were shown to exhibit cytotoxic and procoagulant activities potentially implicated in bacterial dissemination into the circulation and acute pulmonary decline detected in susceptible CF patients. Improved understanding of the mechanisms accounting for B. cenocepacia-induced clinical decline has the potential to indicate novel therapeutic strategies to be included in the care B. cenocepacia-infected patients.

Coagulation activation in autoimmune bullous diseases

The main autoimmune blistering skin disorders are pemphigus vulgaris (PV) and bullous pemphigoid (BP). They differ in the inflammatory infiltrate, which is more intense in BP. Inflammation is known to activate coagulation in several disorders. Local and systemic activation of coagulation was evaluated in BP and PV. We studied 20 BP patients (10 active and 10 remittent), 23 PV patients (13 active and 10 remittent) and 10 healthy subjects. The coagulation markers prothrombin fragment F1+2 and D-dimer were measured by enzyme-immunoassays in plasma. The presence of tissue factor (TF), the main initiator of blood coagulation, was evaluated immunohistochemically in skin specimens from 10 patients with active PV, 10 patients with active BP and 10 controls. Plasma F1+2 and D-dimer levels were significantly high in active BP (P = 0.001), whereas in active PV the levels were normal. During remission, F1+2 and D-dimer plasma levels were normal in both BP and PV. TF immunoreactivity was found in active BP but neither in active PV nor in normal skin. TF reactivity scores were higher in active BP than in controls or active PV (P = 0.0001). No difference in TF scores was found between active PV and controls. BP is associated with coagulation activation, which is lacking in PV. This suggests that BP but not PV patients have an increased thrombotic risk. The observation that thrombotic complications occur more frequently in BP than in PV further supports this view.

Tissue factor pathway inhibitor and P-selectin as markers of sepsis-induced non-overt disseminated intravascular coagulopathy

Inflammation and coagulation occur concomitantly in sepsis. Thrombin activates platelet that leads to P-selectin translocation, which upregulate tissue factor (TF) generation. Tissue factor pathway inhibitor (TFPI) is an anticoagulant that modulates coagulation induced by TF. The term non-overt disseminated intravascular coagulation (DIC) refers to a state of affairs prevalent before the occurrence of overt DIC. It was suggested that an initiation of treatment in non-overt DIC has better outcome than overt DIC. This study investigated the role of TFPI level, P-selectin, and thrombin activation markers in non-overt and overt DIC induced by sepsis and its relationship to outcome and organ dysfunction as measured by the Sequential Organ Failure Assessment (SOFA) score. It included 176 patients with sepsis. They were admitted to the pediatric intensive care unit (ICU).They included 144 cases of non-overt DIC and 32 cases of overt DIC. There was a significant difference in hemostatic markers, platelet count, partial thromboplastin time (PTT), P-selectin, thrombin activation markers, TFPI, and DIC score between overt and non-overt DIC in both groups. It was noticed that P-selectin was positively correlated with DIC score, fibrinogen consumption, fibrinolysis (D-dimer), thrombin activation markers, and TFPI. Tissue factor pathway inhibitor was significantly correlated with fibrinolysis, DIC score, and prothrombin fragment 1+2. Sequential Organ Failure Assessment score was correlated with DIC score and other hemostatic markers in patients with overt DIC. To improve the outcome of patients with DIC, there is a need to establish more diagnostic criteria for non-overt-DIC. Plasma levels of TFPI and P-selectin may be helpful in this respect.

The effect of anticoagulants and the role of thrombin on neutrophil-endothelial cell interactions in septic shock

To examine the effects of anticoagulants and the role of thrombin on neutrophil-platelet-endothelial cell interactions in septic shock. Controlled experiments using phase-contrast microscopy to study neutrophil, platelet, and endothelial cell interactions in flowing cell suspensions under simulated physiologic conditions. University research laboratory. Adult patients with septic shock and normal volunteers. Microslides were coated with human umbilical vein endothelial cells. Neutrophils and platelets removed from control subjects were stimulated with plasma from patients in septic shock and perfused over endothelial cells. Heparin (H), argatroban (A), antithrombin III (ATIII), and recombinant human activated protein C (rhAPC) with and without thrombin were added to cells suspended in septic plasma and normal plasma. The number of neutrophils adherent to endothelial cells, neutrophil rolling velocity, and the number of neutrophils in aggregates were determined. Flow cytometric analysis of cells was used to identify cell activation and the formation of platelet-neutrophil aggregates. Heparin, A, ATIII, rhAPC all significantly decreased neutrophil adhesion and aggregation, and increased rolling velocity of neutrophils suspended in septic plasma. These results are similar to those observed with normal plasma but present greater absolute changes. Platelet-neutrophil aggregation, platelet activation, and neutrophil activation were significantly decreased by each of the anticoagulants. The addition of thrombin to cell suspensions containing anticoagulants reversed the effects of H, A, ATIII, rhAPC on neutrophil adhesion, adherence, and rolling velocity. In addition, thrombin attenuated the effects of each of these agents on platelet-neutrophil aggregation, platelet activation, and neutrophil activation. These data suggest that H, A, ATIII, and rhAPC decrease sepsis-induced neutrophil-endothelial cell interactions. The reversal of this effect by thrombin suggests that these agents alter neutrophil-endothelial interactions through their anticoagulant effects and the resulting decrease in thrombin activity.

Tissue factor/FVIIa activates Bcl-2 and prevents doxorubicin-induced apoptosis in neuroblastoma cells

Background

Tissue factor (TF) is a transmembrane protein that acts as a receptor for activated coagulation factor VII (FVIIa), initiating the coagulation cascade. Recent studies demonstrate that expression of tumor-derived TF also mediates intracellular signaling relevant to tumor growth and apoptosis. Our present study investigates the possible mechanism by which the interaction between TF and FVIIa regulates chemotherapy resistance in neuroblastoma cell lines.

Methods

Gene and siRNA transfection was used to enforce TF expression in a TF-negative neuroblastoma cell line and to silence endogenous TF expression in a TF-overexpressing neuroblastoma line, respectively. The expression of TF, Bcl-2, STAT5, and Akt as well as the phosphorylation of STAT5 and Akt in gene transfected cells or cells treated with JAK inhibitor and LY294002 were determined by Western blot assay. Tumor cell growth was determined by a clonogenic assay. Cytotoxic and apoptotic effect of doxorubicin on neuroblastoma cell lines was analyzed by WST assay and annexin-V staining (by flow cytometry) respectively.

Results

Enforced expression of TF in a TF-negative neuroblastoma cell line in the presence of FVIIa induced upregulation of Bcl-2, leading to resistance to doxorubicin. Conversely, inhibition of endogenous TF expression in a TF-overexpressing neuroblastoma cell line using siRNA resulted in down-regulation of Bcl-2 and sensitization to doxorubicin-induced apoptosis. Additionally, neuroblastoma cells expressing high levels of either endogenous or transfected TF treated with FVIIa readily phosphorylated STAT5 and Akt. Using selective pharmacologic inhibitors, we demonstrated that JAK inhibitor I, but not the PI3K inhibitor LY294002, blocked the TF/FVIIa-induced upregulation of Bcl-2.

Conclusion

This study shows that in neuroblastoma cell lines overexpressed TF ligated with FVIIa produced upregulation of Bcl-2 expression through the JAK/STAT5 signaling pathway, resulting in resistance to apoptosis. We surmise that this TF-FVIIa pathway may contribute, at least in part, to chemotherapy resistance in neuroblastoma.

Profiling of differentially expressed genes in porcine epithelial cells derived from periodontal ligament and gingiva by DNA microarray

OBJECTIVE

It is unknown which genes are differentially expressed in cultured epithelial cells derived from the epithelial rests of Malassez (ERM) in periodontal ligament and oral gingival epithelium (OGE). This study analysed the different gene expression of OGE and ERM cells using a DNA microarray technique.

DESIGN

Epithelial cells from ERM and OGE were isolated from porcine periodontal ligament and oral gingival epithelium. Each RNA sample extracted from the cells was reverse transcribed into cDNA and labelled with either cytidine 5-dUTP (Cy5) or cytidine 3-dUTP (Cy3). These labelled cDNA probes were then mixed and simultaneously hybridised to the Pig 13K microarray plate bearing 13,295 different genes (Operon, AL). Cellular enzyme-linked immunosorbent assay (CELISA) was performed to confirm the expression at protein level.

RESULTS

There were nine genes common to the triplicate microarrays in ERM cells and one in OGE cells. Four of the nine genes including tissue factor (TF), FAT cadherin (FAT) and two unknown genes were expressed at levels more than threefold higher in ERM cells than in OGE cells. The protein levels of both TF and FAT in ERM cells were significantly higher than those in OGE.

CONCLUSION

TF and FAT may act as markers to distinguish ERM cells from OGE cells in vitro.

Haemostatic imbalance following carrageenan-induced rat paw oedema

Carrageenan-induced rat paw oedema is a widely used model to investigate the physiopathology of an acute local inflammation. Recently, much attention has been focused on the link between haemostasis and inflammation, and on the impact that inflammation might have on thrombotic events. It is known that the systemic response to inflammation is the "acute phase reaction" that represents a highly complex reaction of the organism to a variety of injuries, aimed to restore homeostasis; one important feature of the acute phase reaction is the hepatic synthesis of proteins involved in the coagulation cascade. Much attention has been focused on the role that systemic inflammation might have on thrombotic events, while there is not much information on the role played by an acute local inflammation on haemostasis, that can lead toward a pro-thrombotic state. The present study was conducted to evaluate the haemostatic balance in the early and the late phase of carrageenan-induced rat paw oedema; i.e. at 3 h, when paw inflammation is maximally expressed, and 24 h following carrageenan injection, when there is an almost complete absence of local inflammatory symptoms. We found that in inflamed animals, 24 h following oedema induction, there was an increase in plasma fibrinogen levels, antithrombin III activity and serum interleukin-6 levels, concomitant to a shortened prothrombin time and to an increased platelet responsiveness to ADP. Furthermore, in inflamed tissues at 3 h there was an increase in antithrombin III proteic expression. Our results demonstrate that a haemostatic imbalance occurs following carrageenan-induced rat paw oedema.

Epistatic effect of plasminogen activator inhibitor 1 and beta-fibrinogen genes on risk of glomerular microthrombosis in lupus nephritis: interaction with environmental/clinical factors

OBJECTIVE

Glomerular microthrombosis (GMT) is not uncommon in lupus nephritis and has been associated with active renal injury and progressive kidney destruction. We undertook this study to determine whether genetic variations of hemostasis factors, such as plasminogen activator inhibitor 1 (PAI-1) and fibrinogen, affect the risk of GMT.

METHODS

A cross-sectional cohort of 101 lupus nephritis patients with or without GMT was genotyped for PAI-1 -675 4G/5G and beta-fibrinogen (FGB) -455 G/A gene polymorphisms and analyzed.

RESULTS

PAI-1 4G/4G homozygotes and FGB A allele carriers were both at increased risk for GMT. When the data were stratified for both gene polymorphisms, an epistatic effect was detected. The PAI-1 4G/4G genotype was found to predispose to GMT not equally in all lupus nephritis patients, but only in FGB A allele carriers. Likewise, the association between the FGB A allele and GMT was restricted to lupus nephritis patients homozygous for the PAI-1 4G allele. This epistatic effect was revalidated by the multifactor dimensionality reduction (MDR) analysis and further assessed by incorporating a variety of environmental and clinical factors into the MDR analysis. The most parsimonious model that had a cross-validation consistency of 100% included joint effects of PAI-1 and FGB gene polymorphisms and anticardiolipin antibody (aCL) status and yielded the best prediction of GMT, with 66.6% accuracy.

CONCLUSION

Our findings suggest that risk of GMT in lupus nephritis is attributable, at least in part, to an epistatic effect of PAI-1 and FGB genes, likely via an interaction with environmental/clinical factors, such as aCL.

Immune regulation by microvascular endothelial cells: directing innate and adaptive immunity, coagulation, and inflammation

An effective immune response depends not only on the proper activation, regulation, and function of immune cells, but also on their distribution and retention in diverse tissue microenvironments where they encounter a number of stimuli and other cell types. These activities are mediated by endothelial cells, which form specialized microcirculatory networks used by immune cells under both physiological and pathological circumstances. Endothelial cells represent a highly heterogeneous population of cells with the ability to interact with and modulate the function of immune cells. This review is focused on the role of microvascular endothelial cells in innate and adaptive immunity, inflammation, coagulation, angiogenesis, and the therapeutic implications of targeting endothelial cells in selected autoimmune and chronic inflammatory disorders.

PECAM-1 modulates thrombin-induced tissue factor expression on endothelial cells

Platelet endothelial cell adhesion molecule-1 (PECAM-1) (CD31) is known to inhibit platelet function and thrombus formation. The mechanisms involved in PECAM-1's roles as a modulator of hemostasis are still not completely understood. We examined the role of PECAM-1 as a regulator of tissue factor (TF) expression, a known important inducer of thrombosis. Wildtype and CD31KO mice underwent transient (30 min) renal ischemia followed by 24 h re-perfusion and their kidneys assessed for apoptosis, fibrin formation, and tissue factor expression. CD31KO mice exhibited increased tubular epithelial and endothelial apoptosis, increased fibrin deposition, and tissue factor expression. Human umbilical vein endothelial cells (HUVEC) transfected with antisense (AS) PECAM-1 oligonucleotides to downregulate PECAM-1 expression, exhibited greater induction of TF mRNA and protein expression as well as increased expression and nuclear localization of the transcription factor Egr-1 compared to scrambled AS PECAM-1 (Scr)-treated HUVEC following thrombin stimulation. TF induction was found to be mediated through thrombin receptor PAR-1 and the Galphai/o subunit of G-protein, confirmed by PAR-1 antagonist and pertussis toxin inhibition respectively. Thrombin-mediated TF induction was dependent on Rho Kinase activity, phosphorylation of p38(MAPK) and p85 & Akt dephosphorylation. The inverse correlation of PI3K-Akt phosphorylation with p38 (MAPK) phosphorylation was confirmed by pharmacological inhibition. These studies suggest that PECAM-1 is involved in regulating a signaling pathway, affecting PI3K and Akt activation, p38 (MAPK) phosphorylation, which in turn, affects Egr-1 expression and nuclear translocation, ultimately affecting TF expression. These findings provide new insights into the action of PECAM-1 as a modulator of thrombosis.

Basal cells of the human adult airway surface epithelium retain transit-amplifying cell properties

In numerous airway diseases, such as cystic fibrosis, the epithelium is severely damaged and must regenerate to restore its defense functions. Although the human airway epithelial stem cells have not been identified yet, we have suggested recently that epithelial stem/progenitor cells exist among both human fetal basal and suprabasal cell subsets in the tracheal epithelium. In this study, we analyzed the capacity of human adult basal cells isolated from human adult airway tissues to restore a well-differentiated and functional airway epithelium. To this end, we used the human-specific basal cell markers tetraspanin CD151 and tissue factor (TF) to separate positive basal cells from negative columnar cells with a FACSAria cell sorter. Sorted epithelial cells were seeded into epithelium-denuded rat tracheae that were grafted subcutaneously in nude mice and on collagen-coated porous membranes, where they were grown at the air-liquid interface. Sorted basal and columnar populations were also analyzed for their telomerase activity, a specific transit-amplifying cell marker, by the telomeric repeat amplification protocol assay. After cell sorting, the pure and viable CD151/TF-positive basal cell population proliferated on plastic and adhered on epithelium-denuded rat tracheae, as well as on collagen-coated porous membranes, where it was able to restore a fully differentiated mucociliary and functional airway epithelium, whereas viable columnar negative cells did not. Telomerase activity was detected in the CD151/TF-positive basal cell population, but not in CD151/TF-negative columnar cells. These results demonstrate that human adult basal cells are at least airway surface transit-amplifying epithelial cells.

Linking stress to inflammation

There is ample evidence for the influence of central nervous system modulation through inflammatory cellular reactions under psychosocial stress. These inflammatory reflexes might be of major influence not only for metabolic and vascular disease but also for many autoimmune diseases for which stress has been reported as a risk factor. In prospective trials on the influence of risk factors for the occurrence of cardiovascular events, both psychosocial stress and autonomic nervous control of the cardiovascular system were shown to have a major impact on event rates. The underlying cause of these findings seems to be explained in part by the direct influences of autonomic reflexes, potentially induced by psychosocial tasks, on the progression of atherosclerosis. Hence, future prospective studies that aim at deciphering the influence of chronic psychosocial stress and autonomic function on the pathogenesis of inflammatory and metabolic disease will need to include neurophysiologic, molecular, and clinical parameters. Because the neuroimmunologic axis can be seen as a system connecting mental states with inflammatory reactions, pro-inflammatory mediators and anti-inflammatory strategies should be studied as such in experimental settings.