Effects of TNF-α and curcumin on the expression of thrombomodulin and endothelial protein C receptor in human endothelial cells

Exploring the association between circulating endothelial protein C receptor and disease activity of rheumatoid arthritis in a pilot study

Objectives

To investigate whether circulating endothelial protein C receptor (EPCR) is associated with disease activity and inflammatory markers in rheumatoid arthritis.

Methods

Thirty-eight RA patients and 21 healthy controls (HC) were recruited via the A3BC biobank. Peripheral blood mononuclear cells and plasma were isolated from the blood of these participants. Plasma soluble (s)EPCR, IL-6, IL-17 and sCD14 were measured by enzyme-linked immunosorbent assay, cell membrane-associated (m)EPCR by flow cytometry; EPCR gene H3 single nucleotide polymorphism (SNP), which contributes to high plasma sEPCR levels, by PCR and DNA sequencing. Data were analysed using FlowJo10 and GraphPad Prism 10.

Results

RA patients had higher levels of mEPCR on T cells and plasma sEPCR compared with HC. No difference in the EPCR gene H3 SNP G genotype frequency was found between RA and HC. This SNP was significantly correlated with higher sEPCR levels in HC but not in RA patients. In RA, plasma sEPCR levels were positively correlated with IL-6, IL-17, sCD14, anti-CCP and rheumatoid factor. In contrast, mEPCR levels on T cells and natural killer cells (NK) were inversely associated with disease activity measures including 28/66 swollen joint count, 28/68 tender joint count and/or DAS28-CRP/ESR scores, and positively correlated with EPCR gene H3 SNP, which was also correlated with lower disease activity measures in RA.

Conclusion

Our findings suggest that EPCR may play an important role in RA, with plasma sEPCR being potentially associated with inflammatory markers and mEPCR and the EPCR gene H3 SNP possibly related to disease activity measures.

Ponatinib Induces a Procoagulant Phenotype in Human Coronary Endothelial Cells via Inducing Apoptosis

BCR-ABL tyrosine kinase inhibitors (TKIs) are effective drugs in the treatment of patients with chronic myeloid leukemia. However, based on clinical studies, ponatinib was associated with the development of thrombotic complications. Since endothelial cells (ECs) regulate blood coagulation, their abnormal phenotype may play a role in the development of thrombotic events. We here aimed to investigate the effect of ponatinib on the procoagulant activity of cultured endothelial cells in vitro. Human coronary artery endothelial cells (HCAECs) were incubated with 50, 150, and 1000 nM of ponatinib. Subsequently, phosphatidylserine (PS) exposure and endothelial microvesicles (EMVs) were measured by flow cytometry. In addition, EC- and EMV-dependent thrombin generation was analyzed. To investigate pro-apoptotic effects of ponatinib, the level of Bax and Bcl-xL proteins were studied using Western blot and F3, THBD, and VCAM1 mRNAs were quantified by qPCR. Therapeutic concentrations of ponatinib significantly increased PS expression on ECs and the amount of EMVs which significantly shortened the time parameters of thrombin generation. In addition, these changes were associated with an increased ratio of Bax and Bcl-xL proteins in the presence of the decreased THBD mRNA level. Overall, ponatinib enhances the procoagulant activity of ECs via inducing apoptosis, which may contribute to thrombotic events.

Acute myocardial infarction in an untreated patient with acute myeloid leukemia

Key Clinical Message

Acute leukemia, particularly AML, is closely associated with thrombotic events, driven by complex factors like coagulation system changes, endothelial dysfunction, and leukemic cell interactions with the vascular system. Certain chemotherapy drugs can exacerbate the prothrombotic state. Understanding these dynamics is crucial for effective thromboprophylaxis in carefully selected patients with leukemia.

Abstract

Thrombosis is a significant complication of acute leukemia. Thrombotic events mostly occur at diagnosis or during induction therapy. Here we report the occurrence of myocardial infarction (MI) before initiation of therapy, in a patient with acute myeloid leukemia not otherwise specified (AML NOS) who had no other significant risk factors for coronary artery disease. The occurrence of MI in this patient limited the choice of induction therapy and resulted in mortality. We discuss the pathogenesis and risk factors associated with increased thrombosis in AML and advocate for risk-adapted thromboprophylaxis in this patient population.

Targeting endothelial cells with golden spice curcumin: A promising therapy for cardiometabolic multimorbidity

Cardiometabolic multimorbidity (CMM) is an increasingly significant global public health concern. It encompasses the coexistence of multiple cardiometabolic diseases, including hypertension, stroke, heart disease, atherosclerosis, and T2DM. A crucial component to the development of CMM is the disruption of endothelial homeostasis. Therefore, therapies targeting endothelial cells through multi-targeted and multi-pathway approaches hold promise for preventing and treatment of CMM. Curcumin, a widely used dietary supplement derived from the golden spice Carcuma longa, has demonstrated remarkable potential in treatment of CMM through its interaction with endothelial cells. Numerous studies have identified various molecular targets of curcumin (such as NF-κB/PI3K/AKT, MAPK/NF-κB/IL-1β, HO-1, NOs, VEGF, ICAM-1 and ROS). These findings highlight the efficacy of curcumin as a therapeutic agent against CMM through the regulation of endothelial function. It is worth noting that there is a close relationship between the progression of CMM and endothelial damage, characterized by oxidative stress, inflammation, abnormal NO bioavailability and cell adhesion. This paper provides a comprehensive review of curcumin, including its availability, pharmacokinetics, pharmaceutics, and therapeutic application in treatment of CMM, as well as the challenges and future prospects for its clinical translation. In summary, curcumin shows promise as a potential treatment option for CMM, particularly due to its ability to target endothelial cells. It represents a novel and natural lead compound that may offer significant therapeutic benefits in the management of CMM.

Initial Tumor Necrosis Factor-Alpha and Endothelial Activation Are Associated with Hemorrhagic Complications during Extracorporeal Membrane Oxygenation

Studies on inflammatory markers, endothelial activation, and bleeding during extracorporeal membrane oxygenation (ECMO) are lacking. Blood samples were prospectively collected after ECMO initiation from 150 adult patients who underwent ECMO for respiratory failure between 2018 and 2021. After excluding patients who died early (within 48 h), 132 patients were finally included. Their tumor necrosis factor-alpha (TNF-α), tissue factor (TF), soluble thrombomodulin (sTM), and E-selectin levels were measured. A Cox proportional hazards regression model was used to estimate the hazard ratio for hemorrhagic complications during ECMO. The 132 patients were divided into hemorrhagic (n = 23, H group) and non-complication (n = 109, N group) groups. The sequential organ failure assessment score, hemoglobin level, and ECMO type were included as covariates in all Cox models to exclude the effects of clinical factors. After adjusting for these factors, initial TNF-α, TF, sTM, E-selectin, and activated protein C levels were significantly associated with hemorrhagic complications (all p < 0.001). TNF-α, TF, and E-selectin better predicted hemorrhagic complications than the model that included only the aforementioned clinical factors (clinical factors only (area under the curve [AUC]: 0.804), reference; TNF-α (AUC: 0.914); TF (AUC: 0.915); E-selectin (AUC: 0.869)). Conclusions: TNF-α levels were significantly predictive of hemorrhagic complications during ECMO.

The interplay between inflammation and thrombosis in COVID-19: Mechanisms, therapeutic strategies, and challenges

Coronavirus disease 2019 (COVID-19), caused by a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can cause life-threatening pathology characterized by a dysregulated immune response and coagulopathy. While respiratory failure induced by inflammation is the most common cause of death, micro-and macrovascular thrombosis leading to multiple organ failure are also causes of mortality. Dysregulation of systemic inflammation observed in severe COVID-19 patients is manifested by cytokine release syndrome (CRS) - the aberrant release of high levels of proinflammatory cytokines, such as IL-6, IL-1, TNFα, MP-1, as well as complement. CRS is often accompanied by activation of endothelial cells and platelets, coupled with perturbation of the balance between the pro-and antithrombotic mechanisms, resulting in thrombosis. Inflammation and thrombosis form a vicious circle, contributing to morbidity and mortality. Treatment of hyperinflammation has been shown to decrease thrombosis, while anti-thrombotic treatment also downregulates cytokine release. This review highlights the relationship between COVID-19-mediated systemic inflammation and thrombosis, the molecular pathways involved, the therapies targeting these processes, and the challenges currently encountered.

Influence of nanoparticles on the haemostatic balance: between thrombosis and haemorrhage

Maintenance of a delicate haemostatic balance or a balance between clotting and bleeding is critical to human health. Irrespective of administration route, nanoparticles can reach the bloodstream and might interrupt the haemostatic balance by interfering with one or more components of the coagulation, anticoagulation, and fibrinolytic systems, which potentially lead to thrombosis or haemorrhage. However, inadequate understanding of their effects on the haemostatic balance, along with the fact that most studies mainly focus on the functionality of nanoparticles while forgetting or leaving behind their risk to the body's haemostatic balance, is a major concern. Hence, our review aims to provide a comprehensive depiction of nanoparticle-haemostatic balance interactions, which has not yet been covered. The synergistic roles of cells and plasma factors participating in haemostatic balance are presented. Possible interactions and interference of each type of nanoparticle with the haemostatic balance are comprehensively discussed, particularly focusing on the underlying mechanisms. Interactions of nanoparticles with innate immunity potentially linked to haemostasis are mentioned. Various physicochemical characteristics that influence the nanoparticle-haemostatic balance are detailed. Challenges and future directions are also proposed. This insight would be valuable for the establishment of nanoparticles that can either avoid unintended interference with the haemostatic balance or purposely downregulate/upregulate its key components in a controlled manner.

Coagulopathy in Acute Promyelocytic Leukemia: Can We Go Beyond Supportive Care?

Acute promyelocytic leukemia (APL) is characterized by frequent complications due to a distinct coagulopathy. While advances in treatments have improved long-term survival, hemorrhagic and thrombotic complications remain the most common causes of death and morbidity. Improved understanding of the mechanisms of the coagulopathy associated with APL may lead to therapeutic interventions to mitigate the risk of hemorrhage and thrombosis.

Gene expression of thrombomodulin, TNF-α and NF-KB in coronary artery disease patients of Pakistan

Thrombomodulin (THBD) is an endothelial surface glycoprotein receptor, having a pivotal role in maintaining laminar blood flow. It functions to protect endothelial integrity by exhibiting anti-coagulation and anti-inflammatory properties thereby playing a key role in cardiovascular disease (CVD) pathology. Cholesterol lowering drugs have shown to alter the anti-inflammatory effects of cytokines. Understanding the molecular aspects of THBD gene and its relation to inflammatory cytokines is important to identify new prognostic and therapeutic targets for the CVD treatments. The present study was conducted to measure the expression of THBD, TNF-α and NF-kB genes in coronary artery disease patients (CAD) in Pakistani population. Lipid profile and BMI was compared both on fifty CAD patients and fifty healthy individuals. Expression analysis for THBD, TNF-α and NF-kB was carried out using real time PCR. The effect of lipid lowering drugs on cardiometabolic risk variables especially gene expression was analyzed. Our results indicated that the difference in BMI was marginal; however LDL-cholesterol and triglycerides levels in CAD patients were significantly higher than healthy individuals. THBD gene was significantly up-regulated whereas TNF-α and NF-kB were significantly down regulated in CAD individuals. Further exploration revealed that these variations were accounted to the use of statins by the patients. The use of statins by CAD patients up-regulated the mRNA expression of THBD by down-regulation of inflammatory mediators. The enhanced expression of endothelial THBD in response to cholesterol lowering drugs establishes a novel pleiotropic target that can be of clinical significance in thromboembolic and inflammatory disorders.

COVID-19-Associated Coagulopathy: An Exacerbated Immunothrombosis Response

Since the onset of the global pandemic in early 2020, coronavirus disease 2019 (COVID-19) has posed a multitude of challenges to health care systems worldwide. In order to combat these challenges and devise appropriate therapeutic strategies, it becomes of paramount importance to elucidate the pathophysiology of this illness. Coronavirus disease 2019, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), is characterized by a dysregulated immune system and hypercoagulability. COVID-associated coagulopathy (CAC) was recognized based on profound d-dimer elevations and evidence of microthrombi and macrothrombi, both in venous and arterial systems. The underlying mechanisms associated with CAC have been suggested, but not clearly defined. The model of immunothrombosis illustrates the elaborate crosstalk between the innate immune system and coagulation. The rendering of a procoagulant state in COVID-19 involves the interplay of many innate immune pathways. The SARS-CoV2 virus can directly infect immune and endothelial cells, leading to endothelial injury and dysregulation of the immune system. Activated leukocytes potentiate a procoagulant state via release of intravascular tissue factor, platelet activation, NETosis, and inhibition of anticoagulant mechanisms. Additional pathways of specific relevance in CAC include cytokine release and complement activation. All these mechanisms have recently been reported in COVID-19. Immunothrombosis provides a comprehensive perspective of the several synergistic pathways pertinent to the pathogenesis of CAC.

Continuous Formation of Ultrathin, Strong Collagen Sheets with Tunable Anisotropy and Compaction

The multiscale organization of protein-based fibrillar materials is a hallmark of many organs, but the recapitulation of hierarchal structures down to fibrillar scales, which is a requirement for withstanding physiological loading forces, has been challenging. We present a microfluidic strategy for the continuous, large-scale formation of strong, handleable, free-standing, multicentimeter-wide collagen sheets of unprecedented thinness through the application of hydrodynamic focusing with the simultaneous imposition of strain. Sheets as thin as 1.9 μm displayed tensile strengths of 0.5-2.7 MPa, Young's moduli of 3-36 MPa, and modulated the diffusion of molecules as a function of collagen nanoscale structure. Smooth muscle cells cultured on engineered sheets oriented in the direction of aligned collagen fibrils and generated coordinated vasomotor responses. The described biofabrication approach enables rapid formation of ultrathin collagen sheets that withstand physiologically relevant loads for applications in tissue engineering and regenerative medicine, as well as in organ-on-chip and biohybrid devices.

Ginkgo biloba Induces Thrombomodulin Expression and Tissue-Type Plasminogen Activator Secretion via the Activation of Krüppel-Like Factor 2 within Endothelial Cells

The effects of thrombo-prevention, such as antiplatelet and anticoagulant activity, have been reported with the usage of Ginkgo biloba extract (GbE); however, the detailed mechanism has not yet been fully investigated, especially the role of Krüppel-like factor 2 (KLF2). This study aimed to investigate whether GbE can activate KLF2 and then induce thrombomodulin (TM) and tissue-type plasminogen activator (t-PA) secretion to enhance the effects of thrombo-prevention. Different concentrations of GbE were incubated with human umbilical vein endothelial cells (HUVECs) to evaluate its effect on endothelial cells. We found that KLF2 expression is correlated to the risk of atherosclerosis and venous thromboembolism in clinical practice. In the HUVEC cell model, GbE stimulated the expression of KLF2 in a dose-dependent manner. Moreover, TM and t-PA secretion increased when the cells were cultured with GbE. Both the expressions and activities of TM and t-PA in the GbE-treated cells declined after KLF2 was blocked by shKLF2. In sum, with GbE treatment, KLF2 expression in human endothelial cells was significantly activated, which in turn induced an increase in the protein expression and activity of TM and t-PA. After shRNA inhibited the KLF2 expression, GbE stopped inducing the expression and activity of TM and t-PA. These findings suggest that GbE exerts an antithrombotic effect on endothelial cells by increasing the TM expression and t-PA secretion; further, KLF2 is a key factor in this mechanism.

Production and control of coagulation proteins for factor X activation in human endothelial cells and fibroblasts

Human endothelial cells (ECs) synthesize, store, and secrete von Willebrand factor multimeric strings and coagulation factor (F) VIII. It is not currently known if ECs produce other coagulation factors for active participation in coagulation. We found that 3 different types of human ECs in primary culture produce clotting factors necessary for FX activation via the intrinsic (FVIII-FIX) and extrinsic (tissue factor [TF]-FVII) coagulation pathways, as well as prothrombin. Human dermal fibroblasts were used as comparator cells. TF, FVII, FIX, FX, and prothrombin were detected in ECs, and TF, FVII, FIX, and FX were detected in fibroblasts. In addition, FVII, FIX, FX, and prothrombin were detected by fluorescent microscopy in EC cytoplasm (associated with endoplasmic reticulum and Golgi proteins). FX activation occurred on human umbilical vein EC surfaces without the addition of external coagulation proteins, proteolytic enzymes, or phospholipids. Tumour necrosis factor, which suppresses the generation of activated protein C and increases TF, augmented FX activation. Fibroblasts also produced TF, but (in contrast to ECs) were incapable of activating FX without the exogenous addition of FX and had a marked increase in FX activation following the addition of both FX and FVII. We conclude that human ECs produce their own coagulation factors that can activate cell surface FX without the addition of exogenous proteins or phospholipids.

Interplay of Plasmodium falciparum and thrombin in brain endothelial barrier disruption

Recent concepts suggest that both Plasmodium falciparum factors and coagulation contribute to endothelial activation and dysfunction in pediatric cerebral malaria (CM) pathology. However, there is still limited understanding of how these complex inflammatory stimuli are integrated by brain endothelial cells. In this study, we examined how mature-stage P. falciparum infected erythrocytes (IE) interact with tumor necrosis factor α (TNFα) and thrombin in the activation and permeability of primary human brain microvascular endothelial cell (HBMEC) monolayers. Whereas trophozoite-stage P. falciparum-IE have limited effect on the viability of HBMEC or the secretion of pro-inflammatory cytokines or chemokines, except at super physiological parasite-host cell ratios, schizont-stage P. falciparum-IE induced low levels of cell death. Additionally, schizont-stage parasites were more barrier disruptive than trophozoite-stage P. falciparum-IE and prolonged thrombin-induced barrier disruption in both resting and TNFα-activated HBMEC monolayers. These results provide evidence that parasite products and thrombin may interact to increase brain endothelial permeability.

Endothelial cell surface limits coagulation without modulating the antithrombin potency

Antithrombin (AT) binds in vitro and in vivo to endothelial cells through various receptors, including heparan sulphate glycosaminoglycan (HSPG) that could modulate the AT activity. A thrombin generation assay (TGA) was set up at the surface of HUVEC and HMVEC evaluating their participation in the coagulation-anticoagulation processes. TGA induced by 0.5 pM Tissue Factor was performed in normal or AT-deficient plasma spiked with various amounts of recombinant or plasma-derived AT (0, 0.1, 0.5 and 1.0 U/ml). To evaluate the role of HSPG or cellular anticoagulant receptors, cells were treated or not with heparin, a mix of heparanase I, II and III, a neutralizing anti-Endothelial Protein C Receptor (EPCR) or with an anti-Tissue Factor Pathway Inhibitor (TFPI) antibody. The presence of the cells diminished the TG in normal plasma and maintained anticoagulation in AT-deficient plasma. Spiking the AT-deficient plasma with different doses of AT demonstrated that the cells did not amplify the anticoagulant activity of AT. The recombinant AT binds the cells with a higher avidity than the plasma-derived one but this did not affect its anticoagulant potency. Moreover both bindings are independent of the HSPG. The antithrombotic activity kept in absence of AT was not inhibited by blocking antibodies directed against EPCR or TFPI. Our data did not reveal a major co-factor activity for AT from endothelial cells that could have been mediated by HSPG. In contrast, it reveals the presence of alternative anti-coagulant system(s) in two venous cell types that maintain an antithrombotic activity.

Effect of cigarette smoke extract and nicotine on the expression of thrombomodulin and endothelial protein C receptor in cultured human umbilical vein endothelial cells

The present study investigated the influence of cigarette smoke extract (CSE) and nicotine on the expression of thrombomodulin (TM) and endothelial protein C receptor (EPCR) in human umbilical vein endothelial cells (HUVECs). Smoking is associated with intravascular thrombosis. As a vital anticoagulation cofactor, TM is located on the endothelial cell surface and regulates intravascular coagulation by binding to thrombin, hence activating protein C. Activated protein C is a natural anticoagulant that interacts with EPCR to enhance the function of anticoagulation system. The effects of CSE (0.5–5%) and nicotine (10-3-10-9 mol/l) on the expression of TM and EPCR in HUVECs were observed. Reverse transcription-quantitative polymerase chain reaction and flow cytometric analysis techniques were used for detecting TM and EPCR mRNA and protein expression levels, respectively. After 6-h exposure, TM protein and mRNA expression levels decreased in a dose-dependent manner. Stimulation with 5% CSE for 0, 6, 10, 12 and 24 h led to a decrease in the levels of TM mRNA and protein over time, which reached a peak at 12 h. The levels were significantly reduced compared with the control group (P<0.001). However, CSE had no effect on EPCR. Furthermore, nicotine had no influence on TM and EPCR. In conclusion, the present study supports a novel molecular mechanism of cigarette smoking-associated thrombosis by the decreased expression of TM. Further studies are required to identify specific components in CSE responsible for decreasing TM expression and its associated consequences.

The Endothelial Protein C Receptor Is a Potential Stem Cell Marker for Epidermal Keratinocytes

Endothelial protein C receptor (EPCR) is a specific receptor for anticoagulant protein C and expressed by human epidermis and cultured keratinocytes. Here we investigated whether: (a) the level of EPCR in keratinocytes is associated with their growth potential; and (b) EPCR is a potential marker for human epidermal stem cells. Human keratinocytes isolated from foreskins or adult skin tissues were transfected with EPCR siRNA or EPCR overexpressing plasmids. Cell proliferation, long term proliferation potential, colony forming efficiency (CFE), and in vitro epidermal regeneration ability of EPCR^high and EPCR^l °^w cells were assessed. The expression and colocalization of EPCR with stem cell markers p63, integrin β1, and activation of MAP kinases were detected by flow cytometry, immunofluorescence staining, or Western blot. Results showed that EPCR was highly expressed by the basal layer of skin epidermis. EPCR^high cells were associated with the highest levels of p63 and integrin β1. Most EPCR^high cells were smaller in size, formed larger colonies and had a greater long term growth potential, CFE, holoclone formation, and in vitro epidermal regeneration ability when compared to EPCR^l °^w cells. Blocking EPCR resulted in keratinocyte apoptosis, particularly in nondifferentiated conditions. Cell proliferation and p63 expression were reduced by blocking EPCR and enhanced by overexpressing this receptor. These data indicate that EPCR can regulate p63, is associated with highly proliferative keratinocytes, and is a potential human epidermal stem cell marker. Stem Cells 2017;35:1786-1798.

The role of leukocytes in thrombosis

In recent years, the traditional view of the hemostatic system as being regulated by a coagulation factor cascade coupled with platelet activation has been increasingly challenged by new evidence that activation of the immune system strongly influences blood coagulation and pathological thrombus formation. Leukocytes can be induced to express tissue factor and release proinflammatory and procoagulant molecules such as granular enzymes, cytokines, and damage-associated molecular patterns. These mediators can influence all aspects of thrombus formation, including platelet activation and adhesion, and activation of the intrinsic and extrinsic coagulation pathways. Leukocyte-released procoagulant mediators increase systemic thrombogenicity, and leukocytes are actively recruited to the site of thrombus formation through interactions with platelets and endothelial cell adhesion molecules. Additionally, phagocytic leukocytes are involved in fibrinolysis and thrombus resolution, and can regulate clearance of platelets and coagulation factors. Dysregulated activation of leukocyte innate immune functions thus plays a role in pathological thrombus formation. Modulation of the interactions between leukocytes or leukocyte-derived procoagulant materials and the traditional hemostatic system is an attractive target for the development of novel antithrombotic strategies.

Anti-inflammatory effects of activated protein C on human dendritic cells

Activated protein C (APC) has an anticoagulant action and plays an important role in blood coagulation homeostasis. In addition to its anticoagulant action, APC is known to have cytoprotective effects, such as anti-apoptotic action and endothelial barrier protection, on vascular endothelial cells and monocytes. However, the effects of APC on DCs have not been clarified. To investigate the effects of APC on human DCs, monocytes were isolated from peripheral blood and DC differentiation induced with LPS. APC significantly inhibited the production of inflammatory cytokines TNF-α and IL-6 during differentiation of immature DCs to mature DCs, but did not inhibit the production of IL-12 and anti-inflammatory cytokine IL-10. Interestingly, treatment with 5 μg/mL, but not 25 μg/mL, of APC significantly enhanced production of IL-10. In addition, protein C, which is the zymogen of APC, did not affect production of these cytokines. On the other hand, flow cytometric analysis of DC's surface molecules indicated that APC does not significantly affect expression of CD83, a marker of mDC differentiation, and the co-stimulatory molecules CD40, CD80 and CD86. These results suggest that APC has anti-inflammatory effects on human DCs and may be effective against some inflammatory diseases in which the pathogenesis involves TNF-α and/or IL-6 production.

Anti-inflammatory effects of bamboo salt and sodium fluoride in human gingival fibroblasts--An in vitro study

Dental caries preventive agents, such as sodium fluoride (NaF) and bamboo salt (BS), are known to cause cellular growth that is characterized by morphological and gene expression changes. This study was designed to investigate the dual effect of NaF and BS on interleukin (IL)-1β-induced gingival inflammation. Under in vitro experimental conditions, exposure to a subcytotoxic dose of IL-1β enhanced human gingival fibroblast inflammation, as characterized by increased levels of inflammation-associated proteins. A combination of NaF and BS significantly protected fibroblasts from IL-1β-induced cellular deterioration. Exposure to NaF and BS induced the cell growth and no changes in viability were found with the Lactate Dehydrogenase Assay (LDH) assay at the NaF and BS concentration analyzed. Molecular analysis demonstrated that NaF and BS increased resistance to inflammation by reduction of IL-1β, IL-8, and tumor necrosis factor (TNF)-α production. In addition, NaF and BS decreased the expression of IL-1β, IL-8, and TNF-α mRNA in IL-1β-induced human gingival fibroblast cells. The study identifies a new role for NaF and BS in the IL-1β-induced inflammation of gingival fibroblasts and provides a potential target for gingival protection.

Thrombomodulin promotes diabetic wound healing by regulating toll-like receptor 4 expression

Keratinocyte-expressed thrombomodulin (TM) and the released soluble TM (sTM) have been demonstrated to promote wound healing. However, the effects of high glucose on TM expression in keratinocytes and the role of TM in diabetic ulcer remain unclear. In this study, we demonstrated that expressions of TM and Toll-like receptor 4 (TLR4) were both downregulated in high-glucose cultured human keratinocytes and in skin keratinocytes of diabetic patients. In addition, the wound-triggered upregulation of TM and sTM production was abolished in both high-glucose cultured human keratinocytes and streptozotocin-induced diabetic mouse skin. Furthermore, supplementation of recombinant sTM could increase TLR4 expression and promote cutaneous wound healing in both high-glucose cultured human keratinocytes and diabetic mice. However, in Tlr4-deleted mice, which exhibited delayed wound healing, the therapeutic benefit of recombinant sTM was abrogated. Moreover, our results showed that tumor necrosis factor-α (TNF-α) expression in keratinocytes was dose-dependently upregulated by glucose, and TNF-α treatment downregulated the expression of TM and TLR4. Taken together, high-glucose environment reduces the expression of TM and TLR4 in keratinocytes possibly through the action of TNF-α, and recombinant sTM can increase the TLR4 expression and promote wound healing under diabetic condition.

Regulation of thrombomodulin expression and release in human aortic endothelial cells by cyclic strain

Background and Objectives

Thrombomodulin (TM), an integral membrane glycoprotein expressed on the lumenal surface of vascular endothelial cells, promotes anti-coagulant and anti-inflammatory properties. Release of functional TM from the endothelium surface into plasma has also been reported. Much is still unknown however about how endothelial TM is regulated by physiologic hemodynamic forces (and particularly cyclic strain) intrinsic to endothelial-mediated vascular homeostasis.

Methods

This study employed human aortic endothelial cells (HAECs) to investigate the effects of equibiaxial cyclic strain (7.5%, 60 cycles/min, 24 hrs), and to a lesser extent, laminar shear stress (10 dynes/cm², 24 hrs), on TM expression and release. Time-, dose- and frequency-dependency studies were performed.

Results

Our initial studies demonstrated that cyclic strain strongly downregulated TM expression in a p38- and receptor tyrosine kinase-dependent manner. This was in contrast to the upregulatory effect of shear stress. Moreover, both forces significantly upregulated TM release over a 48 hr period. With continuing focus on the cyclic strain-induced TM release, we noted both dose (0–7.5%) and frequency (0.5–2.0 Hz) dependency, with no attenuation of strain-induced TM release observed following inhibition of MAP kinases (p38, ERK-1/2), receptor tyrosine kinase, or eNOS. The concerted impact of cyclic strain and inflammatory mediators on TM release from HAECs was also investigated. In this respect, both TNFα (100 ng/ml) and ox-LDL (10–50 µg/ml) appeared to potentiate strain-induced TM release. Finally, inhibition of neither MMPs (GM6001) nor rhomboids (3,4-dichloroisocoumarin) had any effect on strain-induced TM release. However, significantly elevated levels (2.1 fold) of TM were observed in isolated microparticle fractions following 7.5% strain for 24 hrs.

Conclusions

A preliminary in vitro investigation into the effects of cyclic strain on TM in HAECs is presented. Physiologic cyclic strain was observed to downregulate TM expression, whilst upregulating in a time-, dose- and frequency-dependent manner the release of TM.

IKKβ regulates endothelial thrombomodulin in a Klf2-dependent manner

BACKGROUND

Endothelial thrombomodulin (TM) is critically involved in anticoagulation, anti-inflammation, cytoprotection and normal fetal development. Tumor necrosis factor alpha (TNFα) suppresses TM expression.

OBJECTIVE

TNFα has been shown to down-regulate TM partly via activation of nuclear factor kappa B (NF-κB). However, because the TM promoter lacks an NF-κB binding site, the direct involvement of NF-κB has been controversial. We investigated the role of the upstream regulatory serine kinase, inhibitory kappa-B kinase-β (IKKβ), in TM expression and function with or without TNFα treatment.

METHODS

Inhibition of IKKβ was achieved by specific chemical inhibitors, siRNA or shRNA. TM expression was assessed by qRT-PCR, Western blot, flow cytometry, luciferase reporter assay and chromatin immune-precipitation (ChIP) assay. TM function was estimated by generation of activated protein C (APC). NF-κB activation was determined by immunocytochemistry.

RESULTS AND CONCLUSIONS

IKKβ inhibition increased TM expression and function, and attenuated TNFα-mediated TM down-regulation. In contrast, inhibition of downstream canonical NF-κB protein family members p50 and p65 (RelA) failed to up-regulate TM expression and did not affect IKKβ inhibition-mediated TM over-expression. However, knockdown of cRel and RelB, family members of the canonical and non-canonical NF-κB pathway, respectively, resulted in TM over-expression. IKKβ inhibition caused over-expression, increased promoter activity and enhanced binding of Krüppel-like factor 2 (Klf2) to the TM promoter, which positively regulates TM expression. Finally, knockdown of Klf2 completely attenuated IKKβ inhibition-mediated TM up-regulation. We conclude that IKKβ regulates TM in a Klf2-dependent manner.

Endothelial outgrowth cells regulate coagulation, platelet accumulation, and respond to tumor necrosis factor similar to carotid endothelial cells

Endothelial cells (ECs) are central regulators of hemostasis, inflammation, and other vascular processes. ECs have been used to cover vascular graft materials in an attempt to improve the biological integration of the grafts with the surrounding tissue. Although EC seeded grafts demonstrated improved patency, the invasive nature of EC harvest has limited the clinical translation of this technique. Endothelial outgrowth cells (EOCs) can be derived from circulating endothelial progenitor cells, which are noninvasively isolated from a peripheral blood draw. Although EOCs have been presumed to regulate hemostasis and inflammation similarly to arterial ECs, there has been limited research that directly compares EOCs to arterial ECs, particularly using pairs of donor-matched cells. This study provides a multifaceted characterization of hemostasis regulation by baboon EOCs and carotid ECs, both in the presence and absence of an inflammatory stimulus, tumor necrosis factor α (TNFα). The expression of genes involved in thrombosis and inflammation was highly similar between ECs and EOCs at a basal state and following TNFα stimulation. ECs and EOCs activated similar levels of protein C and Factor X (FX) at a basal state. Following TNFα treatment, EOCs had less of an increase in tissue factor activity than ECs. Cell-seeded expanded polytetrafluoroethylene vascular grafts demonstrated no significant differences between ECs and EOCs in platelet accumulation or fibrinogen incorporation in a baboon femoral arteriovenous shunt loop. This work demonstrates that EOCs regulate thrombus formation and respond to an inflammatory stimulus similar to ECs, and supports utilizing EOCs as a source for an autologous endothelium in tissue engineering applications.

Bamboo salt attenuates CCl4-induced hepatic damage in Sprague-Dawley rats

Bamboo salt, a Korean folk medicine, is prepared with solar salt (sea salt) and baked several times at high temperatures in a bamboo case. In this study, we compared the preventive effects of bamboo salt and purified and solar salts on hepatic damage induced by carbon tetrachloride in Sprague-Dawley rats. Compared with purified and solar salts, bamboo salts prevented hepatic damage in rats, as evidenced by significantly reduced serum levels of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase (P < 0.05). Bamboo salt (baked 9×) triggered the greatest reduction in these enzyme levels. In addition, it also reduced the levels of the proinflammatory cytokines interleukin (IL)-6, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α. Histopathological sections of liver tissue demonstrated the protective effect of bamboo salt, whereas sections from animals treated with the other salt groups showed a greater degree of necrosis. We also performed reverse transcription-polymerase chain reaction and western blot analyses of the inflammation-related genes iNOS, COX-2, TNF-α, and IL-1β in rat liver tissues. Bamboo salt induced a significant decrease (~80%) in mRNA and protein expression levels of COX-2, iNOS, TNF-α, and IL-1β, compared with the other salts. Thus, we found that baked bamboo salt preparations could prevent CCl₄-induced hepatic damage in vivo.

Curcumin: an orally bioavailable blocker of TNF and other pro-inflammatory biomarkers

TNFs are major mediators of inflammation and inflammation-related diseases, hence, the United States Food and Drug Administration (FDA) has approved the use of blockers of the cytokine, TNF-α, for the treatment of osteoarthritis, inflammatory bowel disease, psoriasis and ankylosis. These drugs include the chimeric TNF antibody (infliximab), humanized TNF-α antibody (Humira) and soluble TNF receptor-II (Enbrel) and are associated with a total cumulative market value of more than $20 billion a year. As well as being expensive ($15 000-20 000 per person per year), these drugs have to be injected and have enough adverse effects to be given a black label warning by the FDA. In the current report, we describe an alternative, curcumin (diferuloylmethane), a component of turmeric (Curcuma longa) that is very inexpensive, orally bioavailable and highly safe in humans, yet can block TNF-α action and production in in vitro models, in animal models and in humans. In addition, we provide evidence for curcumin's activities against all of the diseases for which TNF blockers are currently being used. Mechanisms by which curcumin inhibits the production and the cell signalling pathways activated by this cytokine are also discussed. With health-care costs and safety being major issues today, this golden spice may help provide the solution.

LINKED ARTICLES

This article is part of a themed section on Emerging Therapeutic Aspects in Oncology. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-8.

Tumour necrosis factor in infectious disease

TNF signals through two distinct receptors, designated TNFR1 and TNFR2, which initiate diverse cellular effects that include cell survival, activation, differentiation, and proliferation and cell death. These cellular responses can promote immunological and inflammatory responses that eradicate infectious agents, but can also lead to local tissue injury at sites of infection and harmful systemic effects. Defining the molecular mechanisms involved in TNF responses, the effects of natural and experimental genetic diversity in TNF signalling and the effects of therapeutic blockade of TNF has increased our understanding of the key role that TNF plays in infectious disease.

Mycobacterial trehalose dimycolate reprograms macrophage global gene expression and activates matrix metalloproteinases

Trehalose 6,6'-dimycolate (TDM) is a cell wall glycolipid and an important virulence factor of mycobacteria. In order to study the role of TDM in the innate immune response to Mycobacterium tuberculosis, microarray analysis was used to examine gene regulation in murine bone marrow-derived macrophages in response to 90-μm-diameter polystyrene microspheres coated with TDM. A large number of genes, particularly those involved in the immune response and macrophage function, were up- or downregulated in response to these TDM-coated beads compared to control beads. Genes involved in the immune response were specifically upregulated in a myeloid differentiation primary response gene 88 (MyD88)-dependent manner. The complexity of the transcriptional response also increased greatly between 2 and 24 h. Matrix metalloproteinases (MMPs) were significantly upregulated at both time points, and this was confirmed by quantitative real-time reverse transcription-PCR (RT-PCR). Using an in vivo Matrigel granuloma model, the presence and activity of MMP-9 were examined by immunohistochemistry and in situ zymography (ISZ), respectively. We found that TDM-coated beads induced MMP-9 expression and activity in Matrigel granulomas. Macrophages were primarily responsible for MMP-9 expression, as granulomas from neutrophil-depleted mice showed staining patterns similar to that for wild-type mice. The relevance of these observations to human disease is supported by the similar induction of MMP-9 in human caseous tuberculosis (TB) granulomas. Given that MMPs likely play an important role in both the construction and breakdown of tuberculous granulomas, our results suggest that TDM may drive MMP expression during TB pathogenesis.

Dengue virus enhances thrombomodulin and ICAM-1 expression through the macrophage migration inhibitory factor induction of the MAPK and PI3K signaling pathways

Dengue virus (DV) infections cause mild dengue fever (DF) or severe life-threatening dengue hemorrhagic fever (DHF). The mechanisms that cause hemorrhage in DV infections remain poorly understood. Thrombomodulin (TM) is a glycoprotein expressed on the surface of vascular endothelial cells that plays an important role in the thrombin-mediated activation of protein C. Prior studies have shown that the serum levels of soluble TM (sTM) and macrophage migration inhibitory factor (MIF) are significantly increased in DHF patients compared to levels in DF patients or normal controls. In this study, we investigated how MIF and sTM concentrations are enhanced in the plasma of DHF patients and the potential effect of MIF on coagulation through its influence on two factors: thrombomodulin (TM) and intercellular adhesion molecule-1 (ICAM-1) in endothelial cells and monocytes. Recombinant human macrophage migration inhibitory factor (rMIF) was used to treat monocytic THP-1 cells and endothelial HMEC-1 cells or primary HUVEC cells. The subsequent expression of TM and ICAM-1 was assessed by immunofluorescent staining and flow cytometry analysis. Additionally, the co-incubation of THP-1 cells with various cell signaling pathway inhibitors was used to determine the pathways through which MIF mediated its effect. The data provided evidence that severe DV infections induce MIF expression, which in turn stimulates monocytes or endothelial cells to express TM and ICAM-1 via the Erk, JNK MAPK and the PI3K signaling pathways, supporting the idea that MIF may play an important role as a regulator of coagulation.

Molecular mechanisms of curcumin action: gene expression

Curcumin derived from the tropical plant Curcuma longa has a long history of use as a dietary agent, food preservative, and in traditional Asian medicine. It has been used for centuries to treat biliary disorders, anorexia, cough, diabetic wounds, hepatic disorders, rheumatism, and sinusitis. The preventive and therapeutic properties of curcumin are associated with its antioxidant, anti-inflammatory, and anticancer properties. Extensive research over several decades has attempted to identify the molecular mechanisms of curcumin action. Curcumin modulates numerous molecular targets by altering their gene expression, signaling pathways, or through direct interaction. Curcumin regulates the expression of inflammatory cytokines (e.g., TNF, IL-1), growth factors (e.g., VEGF, EGF, FGF), growth factor receptors (e.g., EGFR, HER-2, AR), enzymes (e.g., COX-2, LOX, MMP9, MAPK, mTOR, Akt), adhesion molecules (e.g., ELAM-1, ICAM-1, VCAM-1), apoptosis related proteins (e.g., Bcl-2, caspases, DR, Fas), and cell cycle proteins (e.g., cyclin D1). Curcumin modulates the activity of several transcription factors (e.g., NF-κB, AP-1, STAT) and their signaling pathways. Based on its ability to affect multiple targets, curcumin has the potential for the prevention and treatment of various diseases including cancers, arthritis, allergies, atherosclerosis, aging, neurodegenerative disease, hepatic disorders, obesity, diabetes, psoriasis, and autoimmune diseases. This review summarizes the molecular mechanisms of modulation of gene expression by curcumin.

Endothelial protein C receptor 1651C/G polymorphism and soluble endothelial protein C receptor levels in women with idiopathic recurrent miscarriage

High levels of soluble endothelial protein C receptor (EPCR) induce coagulation dysfunction by inhibiting protein C activation, and activated protein C (APC) activity. We tested whether EPCR 1651C/G promoter variant and changes in plasma soluble EPCR levels are risk factors for idiopathic recurrent spontaneous miscarriage (RSM). A case-control study involving 283 RSM cases and 380 age and BMI-matched control women. EPCR 1651C/G genotyping was performed by PCR-RFLP method. Plasma-soluble EPCR levels were measured with ELISA. The 1651G allele frequency and C/G genotype were significantly higher in RSM cases than controls; none of the cases or control participants was a 1651G/G homozygote. Lower soluble EPCR levels were seen in RSM cases compared to controls, and higher soluble EPCR levels were seen in 1651C/G compared to 1651C/C carriers in cases and controls. Lower soluble EPCR levels were seen in cases, both in 1651C/C (P = 0.0046) and 1651C/G (P = 0.0032) genotype carriers. Multivariate analysis demonstrated strong association of EPCR 1651C/G [P = 0.011; adjusted odds ratio (aOR) (95% confidence interval [CI] = 3.13 (1.31-7.60)], but not soluble EPCR plasma levels [P = 0.067; aOR (95% CI) = 1.01 (1.00-1.10)], with increased RSM risk. In addition, smoking was independently associated with increased RSM risk [P = 0.002; aOR (95% CI) = 2.86 (1.48-5.52)]. EPCR 1651C/G polymorphism and elevated soluble EPCR levels but low soluble EPCR levels increase the risk of idiopathic RSM. Replication studies on other racial groups, and other EPCR gene variants, are warranted.

Genotoxic stress and activation of novel DNA repair enzymes in human endothelial cells and in the retinas and kidneys of streptozotocin diabetic rats

BACKGROUND

Mammalian excision repair cross-complementing 1 (ERCC1) and ERCC4 (a.k.a xeroderma pigmentosum complementation group F) are nucleotide excision repair enzymes, which excise the 5' end of damaged DNA. ERCC1 and ERCC4 have an interactive relationship with poly (adenosine diphosphate ribose) polymerase (PARP). We studied the role of ERCC1 and ERCC4 in glucose-induced extracellular matrix protein production in human endothelial cells and in the retinas and kidneys of streptozotocin diabetic rats.

METHODS

Human umbilical vein endothelial cells were grown with low (5 mM) and high glucose (25 mM). The cells were subjected to ERCC1 and ERCC4 small interfering RNA transfections, PARP blocker (3-aminobenzamide, ABA) and p300 blocker (curcumin). Retinas and kidneys from 1-month-old streptozotocin diabetic rats with or without treatment with curcumin and ABA were examined. Cells and tissues were studied for oxidative stress markers, fibronectin, ERCC1 and ERCC4, PARP and p300 mRNA. Western blot of nuclear proteins was performed.

RESULTS

ERCC1 and ERCC4 messenger RNA and protein levels were higher in high glucose than in low glucose, along with increasing oxidative stress and augmented p300 and fibronectin production. ABA, curcumin, ERCC1 and ERCC4 silencing reduced such upregulations and oxidative stress. Similar changes were seen in the kidneys and retinas of diabetic rats. ABA and curcumin treatment significantly reduced such changes.

CONCLUSIONS

These data indicate that glucose-induced ERCC1 and ERCC4 upregulation leads to increased fibronectin production via a p300-dependent pathway in umbilical endothelial cells, as well as in the retina and in the kidneys of streptozotocin diabetic rats. ERCC1 and ERCC4 may play important roles in the development of diabetic retinopathy and nephropathy.

Regulation of thrombomodulin expression in prostate cancer cells

In carcinomas the expression of thrombomodulin (TM) is inversely correlated with tumour progression and metastasis. In the present study a decreased TM expression in human prostate cancer cell lines, LNCaP, DU-145, and PC-3, in relation to normal prostate epithelial cells (PrEC) is shown. Sequencing and methylation-specific high resolution melting (MS-HRM) analyses of bisulphite-modified genomic DNA indicates a high degree of methylation in DU-145 cells and lesser degrees in PC-3 and LNCaP cells, whereas in PrEC the TM promoter is unmethylated. The expression of TM is negatively regulated by NF-κB- and GSK3-β-dependent signalling pathways and positively regulated by retinoic acid and transcription factor Sp1 in PrEC, LNCaP and PC-3 cells, but not in DU-145 cells. However, exposure of DU-145 cells to the demethylating agent, 5-aza-2'deoxycytidine, restores the TM expression and its control by retinoic acid, NF-κB- and GSK3-β-dependent signalling. In conclusion, the study establishes that in prostate cancer cell lines relative to PrEC the TM is down-regulated and that the TM promoter is hypermethylated, which seems to be responsible for the down-regulation and failed regulation of TM expression in DU-145 cells.

Thrombin induces an inflammatory phenotype in a human brain endothelial cell line

In this study, we utilized the human brain endothelial cell line, hCMEC/D3, to determine the effects of the coagulation factor, thrombin, on the human blood-brain barrier (BBB). We show that thrombin increased the mRNA and cell surface levels of ICAM-1 and VCAM-1 in hCMEC/D3 cells. Thrombin similarly upregulated several chemokines implicated in human neurological conditions. Additionally, the paracellular permeability of the human BBB in vitro was also increased following thrombin treatment. Overall, this study demonstrates that thrombin can effectively induce an inflamed phenotype in an in vitro human BBB.

Vasoprotection by dietary supplements and exercise: role of TNFα signaling

Vascular dysfunction contributes to the pathogenesis of various cardiovascular diseases. Dietary supplements, including fish oil, dietary fibers, and various natural products, and exercise training exert vasoprotective effects. However, the mechanisms underlying the vasoprotective benefits of dietary supplements and physical activity demand extensive investigation. Accumulating evidence suggests that inflammatory cytokine tumor necrosis factor-alpha (TNFα) plays a pivotal role in the dysregulation of macrovascular and microvascular function. TNFα induces vascular inflammation, monocyte adhesion to endothelial cells, vascular oxidative stress, apoptosis, and atherogenic response and participates in the regulation of thrombosis and coagulation through multiple signaling pathways involving NFκB, Sp1, activator protein 1, JNK, p38, STAT3, and so forth. Dietary supplements and exercise training decrease TNFα production and ameliorate TNFα-mediated pathological changes in vasculature. Thus, the inhibitory effects of dietary supplements and physical exercise on TNFα production and TNFα signaling may contribute to their vasoprotective properties.

MEK5 is activated by shear stress, activates ERK5 and induces KLF4 to modulate TNF responses in human dermal microvascular endothelial cells

OBJECTIVE

ECs lining arteries respond to LSS by suppressing pro-inflammatory changes, in part through the activation of MEK5, ERK5 and induction of KLF4. We examined if this anti-inflammatory pathway operates in human ECs lining microvessels, the principal site of inflammatory responses.

METHODS

We used immunofluorescence microscopy of human skin to assess ERK5 activation and KLF4 expression in HDMECs in situ. We applied LSS to or overexpressed MEK5/CA in cultured HDMECs and assessed gene expression by microarrays and qRT-PCR and protein expression by Western blotting. We assessed effects of MEK5/CA on TNF responses using qRT-PCR, FACS and measurements of HDMEC monolayer electrical resistance. We used siRNA knockdown to assess the role of ERK5 and KLF4 in these responses.

RESULTS

ERK5 phosphorylation and KLF4 expression is observed in HDMECs in situ. LSS activates ERK5 and induces KLF4 in cultured HDMECs. MEK5/CA-transduced HDMECs show activated ERK5 and increased KLF4, thrombomodulin, eNOS, and ICAM-1 expression. MEK5 induction of KLF4 is mediated by ERK5. MEK5/CA-transduced HDMECs are less responsive to TNF, an effect partly mediated by KLF4.

CONCLUSIONS

MEK5 activation by LSS inhibits inflammatory responses in microvascular ECs, in part through ERK5-dependent induction of KLF4.

The relationship of air pollution and surrogate markers of endothelial dysfunction in a population-based sample of children

Background

This study aimed to assess the relationship of air pollution and plasma surrogate markers of endothelial dysfunction in the pediatric age group.

Methods

This cross-sectional study was conducted in 2009-2010 among 125 participants aged 10-18 years. They were randomly selected from different areas of Isfahan city, the second large and air-polluted city in Iran. The association of air pollutants' levels with serum thrombomodulin (TM) and tissue factor (TF) was determined after adjustment for age, gender, anthropometric measures, dietary and physical activity habits.

Results

Data of 118 participants was complete and was analyzed. The mean age was 12.79 (2.35) years. The mean pollution standards index (PSI) value was at moderate level, the mean particular matter measuring up to 10 μm (PM₁₀) was more than twice the normal level. Multiple linear regression analysis showed that TF had significant relationship with all air pollutants except than carbon monoxide, and TM had significant inverse relationship with ozone. The odds ratio of elevated TF was significantly higher in the upper vs. the lowest quartiles of PM₁₀, ozone and PSI. The corresponding figures were in opposite direction for TM.

Conclusions

The relationship of air pollutants with endothelial dysfunction and pro-coagulant state can be an important factor in the development of atherosclerosis from early life. This finding should be confirmed in future longitudinal studies. Concerns about the harmful effects of air pollution on children's health should be considered a top priority for public health policy; it should be underscored in primordial and primary prevention of chronic diseases.

Paclitaxel potentiates inflammatory cytokine-induced prothrombotic molecules in endothelial cells

To overcome the limitations of balloon expandible metal stent-induced neointimal smooth muscle cell proliferation, drug-coated stent devices have been developed. Drug eluting stents release high concentrations of antiproliferative agents, such as paclitaxel, to reduce neointimal hyperplasia. The proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), is known to cause severe endothelial dysfunction and accelerate atherosclerotic lesion progression. The interaction of TNF-alpha and paclitaxel on the release of prothrombotic molecules was examined in endothelial cells. Treatment of endothelial cells with paclitaxel had no direct effect on tissue factor (TF) expression, but TNF-alpha increased TF. Cotreatment of paclitaxel with TNF-alpha markedly augmented the release of TF. TNF-alpha induced release of plasminogen activator inhibitor but no synergism occurred with paclitaxel. Treatment of endothelial cells with paclitaxel and TNF-alpha reduced expression of thrombomodulin and protein C receptor. Tissue factor pathway inhibitor expression was reduced by prolonged treatment with either paclitaxel or TNF-alpha. The adhesion molecule, CD62 E, was induced by TNF-alpha; however, CD31, CD62 P, and CD106 were not affected by paclitaxel and TNF-alpha. Apoptosis was not observed with cotreatment of endothelial cells with paclitaxel and TNF-alpha. CD59-positive microparticles were released in response to TNF-alpha, but the release was not augmented by paclitaxel. Paclitaxel and TNF-alpha increased the nitrotyrosination of proteins. These findings indicate that paclitaxel enhances TNF-alpha-induced release of TF, and downregulated thrombomodulin, increased protein nitration, which may subsequently favor prothrombotic intimal surface.

Transcriptional coactivator p300 regulates glucose-induced gene expression in endothelial cells

Sustained hyperglycemia in diabetes causes alteration of a large number of transcription factors and mRNA transcripts, leading to tissue damage. We investigated whether p300, a transcriptional coactivator with histone acetyl transferase activity, regulates glucose-induced activation of transcription factors and subsequent upregulation of vasoactive factors and extracellular matrix (ECM) proteins in human umbilical vein endothelial cells (HUVECs). HUVECs were incubated in varied glucose concentrations and were studied after p300 small interfering RNA (siRNA) transfection, p300 overexpression, or incubation with the p300 inhibitor curcumin. Histone H2AX phosphorylation and lysine acetylation were examined for oxidative DNA damage and p300 activation. Screening for transcription factors was performed with the Luminex system. Alterations of selected transcription factors were validated. mRNA expression of p300, endothelin-1 (ET-1), vascular endothelial growth factor (VEGF), and fibronectin (FN) and its splice variant EDB(+)FN and FN protein production were analyzed. HUVECs in 25 mmol/l glucose showed increased p300 production accompanied by increased binding of p300 to ET-1 and FN promoters, augmented histone acetylation, H2AX phosphorylation, activation of multiple transcription factors, and increased mRNA expression of vasoactive factors and ECM proteins. p300 overexpression showed a glucose-like effect on the mRNA expression of ET-1, VEGF, and FN. Furthermore, siRNA-mediated p300 blockade or chemical inhibitor of p300 prevented such glucose-induced changes. Similar mRNA upregulation was also seen in the organ culture of vascular tissues, which was prevented by p300 siRNA transfection. Data from these studies suggest that glucose-induced p300 upregulation is an important upstream epigenetic mechanism regulating gene expression of vasoactive factors and ECM proteins in endothelial cells and is a potential therapeutic target for diabetic complications.

Contributions of extravascular and intravascular cells to fibrin network formation, structure, and stability

Fibrin is essential for hemostasis; however, abnormal fibrin formation is hypothesized to increase thrombotic risk. We previously showed that in situ thrombin generation on a cell's surface modulates the 3-dimensional structure and stability of the fibrin network. Currently, we compared the abilities of extravascular and intravascular cells to support fibrin formation, structure, and stability. Extravascular cells (fibroblasts, smooth muscle) supported formation of dense fibrin networks that resisted fibrinolysis, whereas unstimulated intravascular (endothelial) cells produced coarse networks that were susceptible to fibrinolysis. All 3 cell types produced a fibrin structural gradient, with a denser network near, versus distal to, the cell surface. Although fibrin structure depended on cellular procoagulant activity, it did not reflect interactions between integrins and fibrin. These findings contrasted with those on platelets, which influenced fibrin structure via interactions between beta3 integrins and fibrin. Inflammatory cytokines that induced prothrombotic activity on endothelial cells caused the production of abnormally dense fibrin networks that resisted fibrinolysis. Blocking tissue factor activity significantly reduced the density and stability of fibrin networks produced by cytokine-stimulated endothelial cells. Together, these findings indicate fibrin structure and stability reflect the procoagulant phenotype of the endogenous cells, and suggest abnormal fibrin structure is a novel link between inflammation and thrombosis.

Relation of Soluble Endothelial Protein C Receptor and Cytokines After Allogeneic Hematopoietic Stem Cell Transplantation

Aim: The objective of this study was to elucidate the effects of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), interleukin 2 (IL-2), interleukin 6 (IL-6), and interleukin 8 (IL-8) on the expression of soluble endothelial protein C receptor (sEPCR) in the pathogenesis of thrombotic complications after hematopoietic stem cell transplantation (HSCT).

Methods: The relationship between plasma concentrations of proinflammatory cytokines (TNF-α, IL-1β, IL-2, IL-6, and IL-8) and sEPCR was evaluated in 32 consecutive allogeneic hematopoietic stem cell—transplanted patients prior to conditioning regimen and randomly once between +5 and +30 days after transplantation and compared these results with 20 healthy controls.

Results: Soluble endothelial protein C receptor levels did not indicate any significant difference between pre- and posttransplantation period, and sEPCR levels showed a significantly negative correlation between IL-6 and IL-8 (sEPCR and IL-6, r = —.43, P < .01; sEPCR and IL-8, r = —.57, P < .01). There was no correlation between sEPCR levels and TNF-α, IL-1β, or IL-2 (sEPCR and TNF-α, r = —.13, P > .05; sEPCR and IL-1β, r = —.1, P ≥ .05; sEPCR and IL-2, r = —.07, P > .05).

Conclusions: Our results suggest that the production of sEPCR was not affected by allogeneic HSCT. Soluble endothelial protein C receptor did not show any positive correlation between these proinflammatory cytokines (TNF-α, IL-1β, IL-2, IL-6, and IL-8), on the contrary a significantly negative correlation was determined between sEPCR and either IL-6 or IL-8. This negative correlation may be a protective mechanism in the pathway of protein C activation.

Activation of endothelial intrinsic NF-{kappa}B pathway impairs protein C anticoagulation mechanism and promotes coagulation in endotoxemic mice

Although the role of systemic activation of the nuclear factor kappaB (NF-kappaB) pathway in septic coagulation has been well documented, little is known about the contribution of endothelial-specific NF-kappaB signaling in this pathologic process. Here, we used transgenic mice that conditionally overexpress a mutant I-kappaBalpha, an inhibitor of NF-kappaB, selectively on endothelium, and their wild-type littermates to define the role of endothelial-specific NF-kappaB in septic coagulation. In wild-type mice, lipopolysaccharide (LPS) challenge (5 mg/kg intraperitoneally) caused markedly increased plasma markers of coagulation, decreased plasma fibrinogen level, and widespread tissue fibrin deposition, which were abrogated by endothelial NF-kappaB blockade in transgenic mice. Endothelial NF-kappaB blockade inhibited tissue factor expression in endothelial cells, but not in leukocytes. Endothelial NF-kappaB blockade did not inhibit LPS-induced tissue factor expression in heart, kidney, and liver. Endothelial NF-kappaB blockade prevented LPS down-regulation of endothelial protein C receptor (EPCR) and thrombomodulin protein expressions, inhibited tissue tumor necrosis factor-alpha converting enzyme activity, reduced EPCR shedding, and restored plasma protein C level. Our data demonstrate that endothelial intrinsic NF-kappaB signaling plays a pivotal role in septic coagulation and suggests a link between endothelial-specific NF-kappaB activation and the impairment of the thrombomodulin-protein C-EPCR anticoagulation pathway.

Regulation of endothelial protein C receptor shedding by cytokines is mediated through differential activation of MAP kinase signaling pathways

The endothelial protein C receptor (EPCR) plays a pivotal role in coagulation, inflammation, cell proliferation, and cancer, but its activity is markedly changed by ectodomain cleavage and release as the soluble protein (sEPCR). In this study we examined the mechanisms involved in the regulation of EPCR shedding in human umbilical endothelial cells (HUVEC). Interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), but not interferon-gamma and interleukin-6, suppressed EPCR mRNA transcription and cell-associated EPCR expression in HUVEC. The release of sEPCR induced by IL-1beta and TNF-alpha correlated with activation of p38 MAPK and c-Jun N-terminal kinase (JNK). EPCR shedding was also induced by phorbol 12-myristate 13-acetate, ionomycin, anisomycin, thiol oxidants or alkylators, thrombin, and disruptors of lipid rafts. Both basal and induced shedding of EPCR was blocked by the metalloproteinase inhibitors, TAPI-0 and GM6001, and by the reduced non-protein thiols, glutathione, dihydrolipoic acid, dithiothreitol, and N-acetyl-l-cysteine. Because other antioxidants and scavengers of reactive oxygen species failed to block the cleavage of EPCR, a direct suppression of metalloproteinase activity seems responsible for the observed effects of reduced thiols. In summary, the shedding of EPCR in HUVEC is effectively regulated by IL-1beta and TNF-alpha, and downstream by MAP kinase signaling pathways and metalloproteinases.

Aurintricarboxylic acid upregulates the thrombomodulin expression of endothelial cells and peripheral blood monocytes

Thrombomodulin has a central role in the regulation of coagulation through its ability to promote generation of the potent anticoagulant, activated protein C. Aurintricarboxylic acid (ATA) has been reported to inhibit platelet function by blocking von Willebrand factor binding to platelet glycoprotein Ib and to impede thrombosis development in vivo. In the present study, we demonstrated a novel antithrombotic effect of ATA. The surface thrombomodulin expression of endothelial cells and peripheral blood monocytes was upregulated by ATA in a dose-dependent and time-dependent manner. ATA also increased the mRNA level of endothelial thrombomodulin in a dose-dependent manner. Tumor necrosis factor (TNF)-alpha (50 ng/ml) or lipopolysaccharide (20 microg/ml) downregulated the expression of endothelial thrombomodulin. Blocking of nuclear factor-kappaB by parthenolide effectively inhibited the TNF-alpha-induced thrombomodulin downregulation of endothelial cells. ATA increased endothelial thrombomodulin expression that was downregulated by TNF-alpha or lipopolysaccharide, in a dose-dependent manner. The inhibition of small G proteins of the Rho family by the Clostridium difficile toxin B-1,0643 did not increase thrombomodulin expression of endothelial cells, and ATA did not activate Rac1 in endothelial cells. These findings provide, at least in part, a novel platelet-independent mechanism of ATA that may explain the demonstrated antithrombotic efficacy of ATA.