Fluvastatin increases the expression of adhesion molecules, monocyte chemoattractant protein-1 and tissue factor in HUVEC stimulated by patient IgG fractions containing antiphospholipid antibodies

Targeting endothelial vascular cell adhesion molecule-1 in atherosclerosis: drug discovery and development of vascular cell adhesion molecule-1-directed novel therapeutics

Vascular cell adhesion molecule-1 (VCAM-1) has been well established as a critical contributor to atherosclerosis and consequently as an attractive therapeutic target for anti-atherosclerotic drug candidates. Many publications have demonstrated that disrupting the VCAM-1 function blocks monocyte infiltration into the sub-endothelial space, which effectively prevents macrophage maturation and foam cell transformation necessary for atherosclerotic lesion formation. Currently, most VCAM-1-inhibiting drug candidates in pre-clinical and clinical testing do not directly target VCAM-1 itself but rather down-regulate its expression by inhibiting upstream cytokines and transcriptional regulators. However, the pleiotropic nature of these regulators within innate immunity means that optimizing dosage to a level that suppresses pathological activity while preserving normal physiological function is extremely challenging and oftentimes infeasible. In recent years, highly specific pharmacological strategies that selectively inhibit VCAM-1 function have emerged, particularly peptide- and antibody-based novel therapeutics. Studies in such VCAM-1-directed therapies so far remain scarce and are limited by the constraints of current experimental atherosclerosis models in accurately representing the complex pathophysiology of the disease. This has prompted the need for a comprehensive review that recounts the evolution of VCAM-1-directed pharmaceuticals and addresses the current challenges in novel anti-atherosclerotic drug development.

Endothelial dysfunction sustains immune response in atherosclerosis: potential cause for ineffectiveness of prevailing drugs

Vascular endothelial dysfunction (ED) forms the cornerstone in the development of atherosclerotic lesions that clinically manifest as ischemia, myocardial infarction, stroke or peripheral arterial disease. ED can be triggered by various risk factors including hypercholesterolemia, hypertension, hyperhomocystenemia and chronic low-grade inflammation. These risk factors also activate immune response systemically. Current drugs used for managing atherosclerosis not only aid in subsiding the risk factor but also suppress the immune activation. Nonetheless, their effectiveness in treating ED is still questionable. Here, we discuss how pathologic molecules and processes pertaining to ED can activate innate and adaptive arms of the immune system leading to disease progression even in the absence of cardiovascular risk factors and the potential of the current drugs, used in the management of atherosclerotic patients, in reversing them. We mainly focus on activated endothelium, endothelial microparticles, mechanically stretched endothelial cells, endothelial mesenchymal transition and endothelial glycocalyx sheds.

Endothelial microparticle release is stimulated in vitro by purified IgG from patients with the antiphospholipid syndrome

IgG antiphospholipid antibodies (aPL) exert direct effects on various cell types, contributing to the pathogenesis of thrombosis and pregnancy morbidity in patients with the antiphospholipid syndrome (APS). Some IgG samples from these patients activate endothelial cells (EC) in vitro as judged by surface expression of adhesion molecules such as E-selectin, which can promote thrombosis. Endothelial micro-particles (EMP), which themselves are potentially prothrombotic, are released by activated EC. Though elevated circulating EMP levels have been reported in patients with APS, it is not known whether these EMP are released due to a direct effect of aPL on the cells. We tested the effect of purified polyclonal IgG from patients with APS (APS-IgG) and healthy controls (HC-IgG) upon cultured human umbilical vein EC (HUVEC). HUVEC exposed to APS-IgG produced significantly more EMP than those exposed to HC-IgG (p=0.0036) and a greater proportion of these EMP carried surface E-selectin (6.2% ± 4.0 for APS-IgG vs. 3.4% ± 2.0 for HC IgG, p=0.0172). This study therefore demonstrates that purified polyclonal APS-IgG can drive EMP release. We propose that EMP generation may be a useful measure of aPL-mediated pathogenic effects upon EC.

Change of concept about the regulation of angiotensin II-induced monocyte chemoattractant protein-1 production in human endothelial cells

AIMS

Some intriguing clinical observations about the anti-inflammatory effects of angiotensin type 1 (AT1) receptor blockers and angiotensin converting enzyme inhibitors in cardiovascular patients brought us to study the signalling pathways which lead to angiotensin II (ANG)-induced monocyte chemoattractant protein-1 (MCP-1) production in human endothelial cells.

METHODS

MCP-1 production in human umbilical vein endothelial cells (HUVECs) under treatments with ANG, AT1 and angiotensin type 2 (AT2) receptor blockers and pravastatin was measured by ELISA. The expression of AT1 and AT2 receptors and NADPH oxidase catalytic subunits (NOX 1-5) was analysed at mRNA and protein levels. Nuclear factor-kappa B (NF-κB) activation was studied by p65 subunit translocation to the cellular nucleus. Cell viability was tested by the MTT method. Nox4 subcellular distribution was analysed by subcellular protein fractionation and by immunoprecipitation followed by matrix-assisted laser desorption/ionization mass spectrometry analysis.

RESULTS

ANG-induced MCP-1 production was mediated by AT2 receptor, but not AT1 receptor in HUVECs in culture, which in turn activated NF-κB, promoting p65 subunit translocation to the nucleus. Reactive oxygen species produced by NADPH oxidase participated in this activation, mainly by the Nox4 subunit, ubiquitously expressed in all the compartments of HUVECs. Pravastatin inhibited ANG-induced MCP-1 production.

CONCLUSIONS

Our results support that ANG-induced MCP-1 production in HUVECs is mediated by AT2 instead AT1 receptor activation, which in turn activates NF-κB involving reactive oxygen species produced by the NADPH oxidase complex. Statins can also block ANG-induced MCP-1 production, probably by their inhibitory effects on NADPH oxidase activity.

Elevation of soluble form of receptor for advanced glycation end products (sRAGE) in recurrent pregnancy losses (RPL): possible participation of RAGE in RPL

OBJECTIVE

To determine whether the soluble receptor for advanced glycation end products (sRAGE) and immune inflammatory markers are associated with recurrent pregnancy losses (RPL).

DESIGN

Prospective case-control study.

SETTING

University clinic.

PATIENT(S)

A total of 93 women (age 35.8±4.6 years) were enrolled including 63 women with three or more recurrent pregnancy losses (RPL), and age-matched fertile controls with a history of at least one live birth and no history of pregnancy losses (n=30).

INTERVENTION(S)

Peripheral blood collection.

MAIN OUTCOME MEASURE(S)

Assessment of anthropometric, metabolic, and inflammatory immune variables.

RESULT(S)

Levels of sRAGE were statistically significantly higher in RPL patients than in control patients (1,528.9±704.5 vs. 1,149.9±447.4 pg/mL). In the multivariate analysis, the levels of insulin, plasminogen activator inhibitor-1, the resistance index of the uterine radial artery, and the ratio of tumor necrosis factor-α/interleukin-10 producing T helper cells were statistically significantly associated with the serum sRAGE level.

CONCLUSION(S)

Elevated levels of serum sRAGE are associated with RPL. The soluble receptor for advanced glycation end products might contribute to RPL by reducing uterine blood flow and subsequently causing ischemia in the fetus via inflammatory and thrombotic reactions.

Cdc42 GTPases facilitate TNF-α-mediated secretion of CCL2 from peripheral nerve microvascular endoneurial endothelial cells

Trafficking of autoreactive leukocytes across the blood-nerve barrier and into peripheral nerves is an early pathological hallmark of Guillain-Barré syndrome (GBS). Tumor necrosis factor-α (TNF-α), a proinflammatory cytokine, promotes transendothelial migration by upregulating endothelial expression of inflammatory mediators, including CCL2, a chemokine implicated in GBS. We sought to determine the mechanism by which TNF-α induces expression and secretion of CCL2 from peripheral nerve microvascular endoneurial endothelial cells (PNMECs). Expression of CCL2 mRNA and protein in quiescent PNMEC cultures was minimal. In contrast, cultures treated with TNF-α exhibited increased CCL2 mRNA and protein content, as well as protein secretion. Simvastatin significantly attenuated TNF-α-induced CCL2 secretion without affecting CCL2 mRNA or protein expression. Co-incubation with geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate, prevented the effect of simvastatin. By comparison, inhibiting protein isoprenylation with GGTI-298, but not FTI-277, mimicked the effect of simvastatin and significantly attenuated transendothelial migration in vitro. Inhibition of the monomeric GTPase Cdc42, but not Rac1 or RhoA-C, attenuated TNF-α-mediated CCL2 secretion. TNF-α-mediated trafficking of autoreactive leukocytes into peripheral nerves during GBS may proceed by a mechanism that involves Cdc42-facilitated secretion of CCL2.

Role of nitric oxide and CCAAT/enhancer-binding protein transcription factor in statin-dependent induction of heme oxygenase-1 in mouse macrophages

The effect of statins on heme oxygenase-1 (HO-1) was compared in 2 murine cell lines, RAW 264.7 and J774A.1 cell lines, and in primary peritoneal macrophages of BALB/c or C57BL/6 mice. The role of endogenous nitric oxide and the type of transcription factors involved were explored. Simvastatin and fluvastatin induced HO-1. Pretreatment of cells with l-NMMA or 1400 W, two different nitric oxide synthase inhibitors, partially blocked statin-dependent induction of HO-1 in RAW 264.7 and J774A.1 but not in primary peritoneal macrophages. Induction of HO-1 by statins was dependent on p-38 MAP kinase activation in all types of macrophages. In RAW 264.7 cells, both statins increased the activity of reporter genes linked to the proximal 1.3 kbp promoter of HO-1 (EC50 of 1.4±0.3 µM for simvastatin and 0.6±0.03 µM for fluvastatin). This effect was significantly blocked by 1400 W (80±5.2% inhibition, p<0.02) and mevalonate, the direct metabolite of HMGCoA reductase. Gel retardation experiments implicated C/EBPβ, AP-1 but not USF, for both RAW 264.7 and primary peritoneal macrophages of C57BL/6 mice. Collectively we showed a differential role of endogenous nitric oxide between macrophage cell lines and primary macrophages and an effect of statins in the protection against inflammation by increasing HO-1 expression.

Statins suppress apolipoprotein CIII-induced vascular endothelial cell activation and monocyte adhesion

Aims

Activation of vascular endothelial cells (ECs) contributes importantly to inflammation and atherogenesis. We previously reported that apolipoprotein CIII (apoCIII), found abundantly on circulating triglyceride-rich lipoproteins, enhances adhesion of human monocytes to ECs in vitro. Statins may exert lipid-independent anti-inflammatory effects. The present study examined whether statins suppress apoCIII-induced EC activation in vitro and in vivo.

Methods and results

Physiologically relevant concentrations of purified human apoCIII enhanced attachment of the monocyte-like cell line THP-1 to human saphenous vein ECs (HSVECs) or human coronary artery ECs (HCAECs) under both static and laminar shear stress conditions. This process mainly depends on vascular cell adhesion molecule-1 (VCAM-1), as a blocking VCAM-1 antibody abolished apoCIII-induced monocyte adhesion. ApoCIII significantly increased VCAM-1 expression in HSVECs and HCAECs. Pre-treatment with statins suppressed apoCIII-induced VCAM-1 expression and monocyte adhesion, with two lipophilic statins (pitavastatin and atorvastatin) exhibiting inhibitory effects at lower concentration than those of hydrophilic pravastatin. Nuclear factor κB (NF-κB) mediated apoCIII-induced VCAM-1 expression, as demonstrated via loss-of-function experiments, and pitavastatin treatment suppressed NF-κB activation. Furthermore, in the aorta of hypercholesterolaemic Ldlr^−/− mice, pitavastatin administration in vivo suppressed VCAM-1 mRNA and protein, induced by apoCIII bolus injection. Similarly, in a subcutaneous dorsal air pouch mouse model of leucocyte recruitment, apoCIII injection induced F4/80+ monocyte and macrophage accumulation, whereas pitavastatin administration reduced this effect.

Conclusions

These findings further establish the direct role of apoCIII in atherogenesis and suggest that anti-inflammatory effects of statins could improve vascular disease in the population with elevated plasma apoCIII.

Antiphospholipid antibodies prolong the activation of endothelial cells induced by necrotic trophoblastic debris: implications for the pathogenesis of preeclampsia

The symptoms of preeclampsia are preceded by endothelial cell activation/dysfunction which is induced by a placental trigger(s) but maternal risk factor(s) also contribute to the pathogenesis of preeclampsia. In this work we have investigated the interactions of a maternal risk factor, antiphospholipid antibodies, and a placental trigger, necrotic trophoblastic debris, on the activation of endothelial cells. Trophoblastic debris, from placental explants, was induced to become necrotic by freeze-thawing then exposed to endothelial cells for 24 h. After washing away residual trophoblastic debris antiphospholipid antibodies or a control antibody were added to the cultures then replaced with fresh medium in the presence or absence of antibodies. Endothelial cell activation was quantified by examining cell-surface ICAM-1 expression and monocyte adhesion. Endothelial cells exposed to necrotic trophoblastic debris for 24 h became activated but the activation was lost 24 h after removal of the debris. Antiphospholipid antibodies alone did not active untreated endothelial cells, but did prolong the activation of endothelial cells which had been activated by pre-treatment with necrotic trophoblastic debris. When exposed to antiphospholipid antibodies the endothelial cells remained activated despite removal of the trophoblastic debris. In contrast, a control antibody did not prolong endothelial cell activation. Our data suggest that in women with antiphospholipid antibodies, activation of endothelial cells induced by necrotic trophoblastic debris could be maintained even if the endothelial cells were only intermittently exposed to necrotic debris. This might in part explain why antiphospholipid antibodies are such a strong maternal risk factor for preeclampsia.

Effect of shear stress, statins and TNF-α on hemostatic genes in human endothelial cells

Atherosclerotic plaque formation and progression are dependent on local shear stress patterns and inflammatory cytokines. Statins effectively reduce the progression of atherosclerosis and the incidence of cardiovascular events. However, the benefit of statins cannot be explained by cholesterol reduction alone. This study, investigated the non-lipid lowering effects of simvastatin and rosuvastatin on endothelial anti- and prothrombotic genes under different biomechanical and inflammatory stress conditions. Endothelial cells responded in a similar way to simvastatin and rosuvastatin. However, they were more sensitive to simvastatin. The statins had anti-inflammatory properties counteracting the TNF-α effect on the hemostatic genes studied. There was no observed synergistic effect between shear stress and simvastatin. Simvastatin had a counteracting effect on t-PA and PAI-1 compared to TNF-α and shear stress. Simvastatin blocked the TNF-α suppressive effect on thrombomodulin and eNOS, irrespective of shear stress. The strong inductive effect of TNF-α on VCAM-1 was counteracted by simvastatin and shear stress in an additive dose-response dependent way.

Fluvastatin and lovastatin inhibit granulocyte macrophage-colony stimulating factor-stimulated human eosinophil adhesion to inter-cellular adhesion molecule-1 under flow conditions

BACKGROUND

Eosinophil accumulation in the lung is an important feature of airway inflammation in asthma. There is therefore much interest in developing novel therapies to prevent this process. Accumulating evidence suggests that statins have anti-inflammatory properties, including inhibition of leucocyte accumulation. We therefore assessed the ability of five statins to inhibit human eosinophil adhesion to recombinant human inter-cellular adhesion molecule (rhICAM)-1 under physiologically relevant flow conditions.

METHODS

Purified eosinophils were pre-treated with a panel of statins before elucidation of the adhesion profiles of resting and granulocyte macrophage-colony stimulating factor (GM-CSF)-stimulated cells to rhICAM-1-coated microchannels at a flow rate of 0.5 dynes/cm(2). Images were recorded in real-time at 1 min intervals and analysed using Ducocell software.

RESULTS

Fluvastatin and lovastatin (both 10 nm) significantly inhibited GM-CSF-stimulated eosinophil adhesion to rhICAM-1 after 2 min (34.4+/-3.0% inhibition and 37.8+/-12.6% inhibition, respectively, n=4, P<0.05) but had no significant inhibitory effect on unstimulated eosinophil adhesion. Mevastatin, simvastatin, and pravastatin (all 10 nm) had no significant effect on GM-CSF-stimulated eosinophil adhesion to rhICAM-1. A concentration range of fluvastatin and lovastatin inhibited GM-CSF stimulated eosinophil adhesion with significant (P<0.05) inhibition observed at low concentrations of 1 nm for both drugs. Mevalonate (100 nm) reversed fluvastatin-mediated but not lovastatin-mediated inhibition of eosinophil adhesion.

CONCLUSIONS

Inhibition of eosinophil adhesion to ICAM-1 by fluvastatin and lovastatin under physiological shear stress represent novel actions by these drugs that may inform the development of anti-inflammatory therapy for allergic disease.

Update on statin-mediated anti-inflammatory activities in atherosclerosis

Anti-inflammatory activities of statins in atherosclerosis have been well documented by both basic research and clinical studies. Statins have been introduced in the 1980s as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors to block cholesterol synthesis and lower cholesterol serum levels. In the last three decades, statins have been shown to possess several anti-inflammatory and antioxidant activities resulting in the beneficial reduction of atherosclerotic processes and cardiovascular risk in both humans and animal models. Inflammatory intracellular pathways involving kinase phosphorylation and protein prenylation are modulated by statins. The same intracellular mechanisms might also cause statin-induced myotoxicity. In the present review, we will update evidence on statin-mediated regulation of inflammatory pathways in atherogenesis.

Tissue factor in the antiphospholipid syndrome

Antiphospholipid (aPL) antibodies are clinically important acquired risk factors for thrombosis and pregnancy loss and are thought to have a direct prothrombotic effect in vivo. Data suggest that a major mechanism by which aPL antibodies contribute to thrombophilia is the upregulation of tissue factor (TF) (CD142) on blood cells and vascular endothelium. TF is the physiological trigger of normal blood coagulation and thrombosis in many hypercoagulable conditions. This article reviews the physiology of TF, the molecular regulation of TF expression and the effects of aPL antibodies on intravascular TF regulation and expression. Inhibition of TF and the pathways by which aPL antibodies induce TF expression are potentially attractive therapeutic targets in the antiphospholipid syndrome.

Insights into atherosclerosis therapy in antiphospholipid syndrome

The presence of early atheroma in antiphospholipid syndrome (APS) underscores the necessity of new therapies for this disorder. Inflammation plays an essential role in the pathogenesis of both APS secondary to systemic lupus erythematosus and atheroma. Several drugs currently used in APS have also anti-atherogenic properties via their anti-inflammatory effect. Furthermore, in addition to screening and treatment of traditional cardiovascular risk factors, it has been suggested that the introduction of some new medication such as statins in APS patients could be useful. This review assesses the current knowledge in this field and the justification for this new therapeutical approach. Furthermore, these data underscore the necessity for the use of other medication for atherosclerosis in APS patients, such as immunomodulatory drugs, which would be complementary to the anti-thrombotic and anti-platelet therapy.

Statins and the vascular endothelial inflammatory response

Statins reduce cholesterol synthesis and are widely used for the treatment of hyperlipidaemia and ischaemic heart disease. Besides their cholesterol-lowering effects, statins also possess broad immunomodulatory and anti-inflammatory properties. Vascular endothelial cells have a crucial role in the pathogenesis of inflammatory disease, and, alongside leukocytes and antigen-presenting cells, represent a key cellular target for statin therapy. Recent studies investigating how these drugs modify endothelial cell function demonstrate that the therapeutic effect of statins can be attributed, in part, to their action on the endothelium. Accordingly, statins attenuate endothelial MHC class II expression, increase endothelial nitric oxide synthase and fibrinolytic activity, decrease leukocyte adhesion and transmigration, and enhance resistance to local injurious stimuli. Many of these effects are brought about by the modulation of small GTPase function and the downregulation of proinflammatory gene expression.

Pathogenic mechanisms of anti-endothelial cell antibodies (AECA): their prevalence and clinical relevance

Anti‐endothelial cell antibodies (AECA) represent a heterogeneous family of autoantibodies directed against structural endothelial proteins, as well as antigens adhering to endothelial cells. Although AECA immunoassays still show a high‐interlaboratory variability, several findings suggest a pathogenic role of these autoantibodies in diseases characterized by endothelial damage. In this chapter, we analyze the knowledge about AECA prevalence, clinical relevance, and their pathogenic role in autoimmune diseases focusing in particular on systemic lupus erythematosus, antiphospholipid syndrome, systemic sclerosis (SSc), and systemic vasculitis.