T lymphocytes induce endothelial cell matrix metalloproteinase expression by a CD40L-dependent mechanism: implications for tubule formation

Hegemony of inflammation in atherosclerosis and coronary artery disease

Inflammation drives coronary artery disease and atherosclerosis implications. Lipoprotein entry, retention, and oxidative modification cause endothelial damage, triggering innate and adaptive immune responses. Recruited immune cells orchestrate the early atherosclerotic lesions by releasing proinflammatory cytokines, expediting the foam cell formation, intraplaque haemorrhage, secretion of matrix-degrading enzymes, and lesion progression, eventually promoting coronary artery syndrome via various inflammatory cascades. In addition, soluble mediators disrupt the dynamic anti- and prothrombotic balance maintained by endothelial cells and pave the way for coronary artery disease such as angina pectoris. Recent studies have established a relationship between elevated levels of inflammatory markers, including C-reactive protein (CRP), interleukins (IL-6, IL-1β), and tumour necrosis factor-alpha (TNF-α) with the severity of CAD and the possibility of future cardiovascular events. High-sensitivity C-reactive protein (hs-CRP) is a marker for assessing systemic inflammation and predicting the risk of developing CAD based on its peak plasma levels. Hence, understanding cross-talk interactions of inflammation, atherogenesis, and CAD is highly warranted to recalculate the risk factors that activate and propagate arterial lesions and devise therapeutic strategies accordingly. Cholesterol-inflammation lowering agents (statins), monoclonal antibodies targeting IL-1 and IL-6 (canakinumab and tocilizumab), disease-modifying antirheumatic drugs (methotrexate), sodium-glucose transport protein-2 (SGLT2) inhibitors, colchicine and xanthene oxidase inhibitor (allopurinol) have shown promising results in reducing inflammation, regressing atherogenic plaque and modifying the course of CAD. Here, we review the complex interplay between inflammatory, endothelial, smooth muscle and foam cells. Moreover, the putative role of inflammation in atherosclerotic CAD, underlying mechanisms and potential therapeutic implications are also discussed herein.

CD40 Ligand-CD40 Interaction Is an Intermediary between Inflammation and Angiogenesis in Proliferative Diabetic Retinopathy

We aimed to investigate the role of the CD40-CD40 ligand (CD40L) pathway in inflammation-mediated angiogenesis in proliferative diabetic retinopathy (PDR). We analyzed vitreous fluids and epiretinal fibrovascular membranes from PDR and nondiabetic patients, cultures of human retinal microvascular endothelial cells (HRMECs) and Müller glial cells and rat retinas with ELISA, immunohistochemistry, flow cytometry and Western blot analysis. Functional tests included measurement of blood-retinal barrier breakdown, in vitro angiogenesis and assessment of monocyte-HRMEC adherence. CD40L and CD40 levels were significantly increased in PDR vitreous samples. We demonstrated CD40L and CD40 expression in vascular endothelial cells, leukocytes and myofibroblasts in epiretinal membranes. Intravitreal administration of soluble (s)CD40L in normal rats significantly increased retinal vascular permeability and induced significant upregulation of phospho-ERK1/2, VEGF, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). sCD40L induced upregulation of VEGF, MMP-9, MCP-1 and HMGB1 in cultured Müller cells and phospo-ERK1/2, p65 subunit of NF-ĸB, VCAM-1 and VEGF in cultured HRMECS. TNF-α induced significant upregulation of CD40 in HRMECs and Müller cells and VEGF induced significant upregulation of CD40 in HRMECs. sCD40L induced proliferation and migration of HRMECs. We provide experimental evidence supporting the involvement of the CD40L-CD40 pathway and how it regulates inflammatory angiogenesis in PDR.

Insights Into the Role of Matrix Metalloproteinases in Cancer and its Various Therapeutic Aspects: A Review

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that regulate the turnover of extracellular matrix (ECM) components. Gross and La Piere discovered MMPs in 1962 during an experiment on tissue samples from a tadpole’s tail. Several subtypes of MMPs have been identified, depending on their substrate specificity and localization. MMPs are involved as essential molecules in multiple and diverse physiological processes, such as reproduction, embryonic development, bone remodeling, tissue repair, and regulation of inflammatory processes. Its activity is controlled at various levels such as at transcription level, pro-peptide activation level and by the activity of a family of tissue inhibitors of metalloproteinase, endogenous inhibitors of MMPs. Cancer metastasis, which is the spread of a tumor to a distant site, is a complex process that is responsible for the majority of cancer-related death It is considered to be an indicator of cancer metastasis. During metastasis, the tumor cells have to invade the blood vessel and degrade the ECM to make a path to new loci in distant places. The degradation of blood vessels and ECM is mediated through the activity of MMPs. Hence, the MMP activity is critical to determining the metastatic potential of a cancer cell. Evasion of apoptosis is one of the hallmarks of cancer that are found to be correlated with the expression of MMPs. As a result, given the importance of MMPs in cancer, we describe the role of these multifunctional enzymes MMPs in various aspects of cancer formation and their rising possibilities as a novel therapeutic target in this review. There is also a brief discussion of various types of therapeutic components and drugs that function against MMPs.

Inverse Regulation of Confluence-Dependent ADAMTS13 and von Willebrand Factor Expression in Human Endothelial Cells

ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) is a zinc-containing metalloprotease also known as von Willebrand factor (vWF)-cleaving protease. Low ADAMTS13 plasma levels are associated with an increased risk of arterial thrombosis, including myocardial infarction and cerebrovascular disease. The expression and regulation of this metalloprotease in human endothelial cells have not been systematically investigated. In this study, we demonstrate that ADAMTS13 expression is inhibited by proinflammatory cytokines tumor necrosis factor-α and interferon-γ as well as by CD40 ligand, which was hitherto unknown. Factors protecting against atherosclerosis such as exposure to continuous unidirectional shear stress, interleukin-10, or different HMG-CoA reductase inhibitors like, e.g., simvastatin, atorvastatin, or rosuvastatin, did not influence ADAMTS13 expression. Unidirectional periodic orbital shear stress, mimicking oscillatory flow conditions found at atherosclerosis-prone arterial bifurcations, had also no effect. In contrast, a reciprocal correlation between ADAMTS13 and vWF expression in endothelial cells depending on the differentiation state was noted. ADAMTS13 abundance significantly rose on both the mRNA and intracellular protein level and also tethered to the endothelial glycocalyx with the degree of confluency while vWF protein levels were highest in proliferating cells but significantly decreased upon reaching confluence. This finding could explain the anti-inflammatory and antithrombotic phenotype of dormant endothelial cells mediated by contact inhibition.

Cardiovascular Effects Mediated by HMMR and CD44

Cardiovascular disease (CVD) is the leading cause of death worldwide. The most dangerous life-threatening symptoms of CVD are myocardial infarction and stroke. The causes of CVD are not entirely clear, and new therapeutic targets are still being sought. One of the factors involved in CVD development among vascular damage and oxidative stress is chronic inflammation. It is known that hyaluronic acid plays an important role in inflammation and is regulated by numerous stimuli, including proinflammatory cytokines. The main receptors for hyaluronic acid are CD44 and RHAMM. These receptors are membrane proteins that differ in structure, but it seems that they can perform similar or synergistic functions in many diseases. Both RHAMM and CD44 are involved in cell migration and wound healing. However, their close association with CVD is not fully understood. In this review, we describe the role of both receptors in CVD.

Matrix metalloproteinase-9 might affect adaptive immunity in non-ST segment elevation acute coronary syndromes by increasing CD31 cleavage on CD4+ T-cells

Aims

In patients with acute coronary syndrome (ACS), the higher activity of effector T-cells suggests that mechanisms involving adaptive immunity dysregulation might play a role in coronary instability. The shedding of the functional CD31 domain 1–5 leads to uncontrolled lymphocyte activation. In experimental models, matrix metalloproteinase-9 (MMP-9) has been implicated in endothelial CD31 cleavage. Interestingly, higher serum levels of MMP-9 have been observed in ACS. We aim to investigate the mechanisms underlying CD31 dysregulation in ACS.

Methods and results

To assess CD31 cleavage on CD4+ T-cells, we analysed by flow cytometry CD4+ T-cells of 30 ACS, 25 stable angina (SA) patients, and 28 controls (CTRL) using two different CD31 antibodies that specifically recognize domain 1–5 or the non-functional membrane-proximal domain 6. The ratio between the domains was significantly lower in ACS than in SA and CTRL (P = 0.002 ACS vs. SA; P = 0.002 ACS vs. CTRL). After stimulation with anti-CD3/CD28, the 1–5/6 domain ratio was significantly lower in ACS than in SA (P = 0.005). ELISA of supernatants obtained from T-cell receptor-stimulated CD4+ T-cells showed higher production of MMP-9 in ACS than in SA (P < 0.001). CD31 domain 1–5 expression in activated CD4+ T-cells from ACS patients increased after treatment with a specific MMP-9 inhibitor (P = 0.042).

Conclusion

Our study suggest that enhanced MMP-9 release plays a key role in determining the cleavage and shedding of the functional CD31 domain 1–5 in CD4+ T-cells of ACS patients. This mechanism might represent an important therapeutic target to modulate T-cell dysregulation in ACS.

The Role of the Extracellular Matrix and Its Molecular and Cellular Regulators in Cancer Cell Plasticity

The microenvironment encompasses all components of a tumor other than the cancer cells themselves. It is highly heterogenous, comprising a cellular component that includes immune cells, fibroblasts, adipocytes, and endothelial cells, and a non-cellular component, which is a meshwork of polymeric proteins and accessory molecules, termed the extracellular matrix (ECM). The ECM provides both a biochemical and biomechanical context within which cancer cells exist. Cancer progression is dependent on the ability of cancer cells to traverse the ECM barrier, access the circulation and establish distal metastases. Communication between cancer cells and the microenvironment is therefore an important aspect of tumor progression. Significant progress has been made in identifying the molecular mechanisms that enable cancer cells to subvert the immune component of the microenvironment to facilitate tumor growth and spread. While much less is known about how the tumor cells adapt to changes in the ECM nor indeed how they influence ECM structure and composition, the importance of the ECM to cancer progression is now well established. Plasticity refers to the ability of cancer cells to modify their physiological characteristics, permitting them to survive hostile microenvironments and resist therapy. Examples include the acquisition of stemness characteristics and the epithelial-mesenchymal and mesenchymal-epithelial transitions. There is emerging evidence that the biochemical and biomechanical properties of the ECM influence cancer cell plasticity and vice versa. Outstanding challenges for the field remain the identification of the cellular mechanisms by which cancer cells establish tumor-promoting ECM characteristics and delineating the key molecular mechanisms underlying ECM-induced cancer cell plasticity. Here we summarize the current state of understanding about the relationships between cancer cells and the main stromal cell types of the microenvironment that determine ECM characteristics, and the key molecular pathways that govern this three-way interaction to regulate cancer cell plasticity. We postulate that a comprehensive understanding of this dynamic system will be required to fully exploit opportunities for targeting the ECM regulators of cancer cell plasticity.

Platelets and matrix metalloproteinases

Matrix metalloproteinases (MMPs) and their inhibitors essentially contribute to a variety of pathophysiologies by modulating cell migration, tissue degradation and inflammation. Platelet-associated MMP activity appears to play a major role in these processes. First, platelets can concentrate leukocyte-derived MMP activity to sites of vascular injury by leukocyte recruitment. Second, platelets stimulate MMP production in e.g. leukocytes, endothelial cells, or tumour cells by direct receptor interaction or/and by paracrine pathways. Third, platelets synthesise and secrete a variety of MMPs including MMP-1, MMP-2, MMP-3, and MMP-14 (MT1-MMP), and potentially MMP-9 as well as the tissue inhibitors of metalloproteinase (TIMPs). This review focuses on platelet-derived and platelet-induced MMPs and their inhibitors.

Effects of interleukin-17 on human retinal vascular endothelial cell capillary tube formation in vitro

The present study aimed to investigate the effect of and mechanism underlying interleukin (IL)‑17 on human retinal vascular endothelial cell (HREC) capillary tube formation in vitro. The expression of IL‑17 receptor (IL‑17R) in human HRECs was quantified using reverse transcriptase‑polymerase chain reaction (RT‑PCR) and western blot analyses. The roles of IL‑17 in HREC migration and capillary tube formation were detected using a wound scratching assay and three‑dimensional Matrigel assay, respectively, in vitro. HREC proliferation was examined using a cell counting kit‑8 assay with administration of serial doses of IL‑17. The effects of IL‑17 on the expression of vascular endothelial growth factor (VEGF), intercellular cell adhesion molecule (ICAM)‑1, IL‑6 and IL‑8 in HRECs were evaluated using RT‑PCR and western blot analyses. The results revealed that the HRECs expressed IL‑17R, and the number of intact capillary tubes formed by HRECs in the presence of IL‑17 was markedly higher, compared with that in the blank control group. The wound scratching assay showed that the numbers of migrated HRECs stimulated with IL‑17 at concentrations of 100 or 500 ng/ml were significantly higher, compared with the number in the control group. The RT‑PCR and western blot analyses showed that IL‑17 significantly promoted the expression of VEGF, ICAM‑1, IL‑6 and IL‑8 by the HRECs. The proliferation of HRECs in the presence of IL‑17 was also significantly increased. Therefore, IL‑17 increased HREC capillary tube formation through promoting HREC migration, proliferation, and expression levels of VEGF, ICAM‑1, IL‑6 and IL-8.

Tryptanthrin Suppresses the Activation of the LPS-Treated BV2 Microglial Cell Line via Nrf2/HO-1 Antioxidant Signaling

Microglia are the resident macrophages in the central nervous system (CNS) and play essential roles in neuronal homeostasis and neuroinflammatory pathologies. Recently, microglia have been shown to contribute decisively to neuropathologic processes after ischemic stroke. Furthermore, natural compounds have been reported to attenuate inflammation and pathologies associated with neuroinflammation. Tryptanthrin (indolo[2,1-b]quinazoline-6,12-dione) is a phytoalkaloid with known anti-inflammatory effects in cells. In present study, the authors confirmed middle cerebral artery occlusion (MCAO) injury triggers the activation of microglia in brain tissue, and investigated whether tryptanthrin influences the function of mouse murine BV2 microglia under LPS-induced inflammatory conditions in vitro. It was found tryptanthrin protected BV2 microglia cells against LPS-induced inflammation and inhibited the induction of M1 phenotype microglia under inflammatory conditions. In addition, tryptanthrin reduced the production of pro-inflammatory cytokines in BV2 microglia cells via nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) signaling and NF-κB signaling. The authors suggest that tryptanthrin might alleviate the progress of neuropathologies by controlling microglial functions under neuroinflammatory conditions.

The Interaction of CD154 with the α5β1 Integrin Inhibits Fas-Induced T Cell Death

CD154, a critical regulator of the immune response, is usually associated with chronic inflammatory, autoimmune diseases as well as malignant disorders. In addition to its classical receptor CD40, CD154 is capable of binding other receptors, members of the integrin family, the αIIbβ3, αMβ2 and α5β1. Given the role attributed to integrins and particularly the β1 integrins in inhibiting apoptotic events in normal as well as malignant T cells, we were highly interested in investigating the role of the CD154/α5β1 interaction in promoting survival of malignant T cells contributing as such to tumor development and/or propagation. To support our hypothesis, we first show that soluble CD154 binds to the T-cell acute lymphoblastic leukemia cell line, Jurkat E6.1 in a α5β1-dependent manner. Binding of soluble CD154 to α5β1 integrin of Jurkat cells leads to the activation of key survival proteins, including the p38 and ERK1/2 mitogen-activated protein kinases (MAPKs), phosphoinositide 3 kinase (PI-3K), and Akt. Interestingly, soluble CD154 significantly inhibits Fas-mediated apoptosis in T cell leukemia-lymphoma cell lines, Jurkat E6.1 and HUT78 cells, an important hallmark of T cell survival during malignancy progression. These anti-apoptotic effects were mainly mediated by the activation of the PI-3K/Akt pathway but also involved the p38 and the ERK1/2 MAPKs cascades. Our data also demonstrated that the CD154-triggered inhibition of the Fas-mediated cell death response was dependent on a suppression of caspase-8 cleavage, but independent of de novo protein synthesis or alterations in Fas expression on cell surface. Together, our results highlight the impact of the CD154/α5β1 interaction in T cell function/survival and identify novel targets for the treatment of malignant disorders, particularly of T cell origin.

Neuroprotective effect of endogenous cannabinoids on ischemic brain injury induced by the excess microglia-mediated inflammation

Increasing evidence has demonstrated the role of endogenous cannabinoids system (ECS) on protecting brain injury caused by ischemia (IMI). Papers reported that microglia-mediated inflammation has become one of the most pivotal mechanisms for IMI. This study was aimed to investigate the potential roles of ECS on neuron protection under microglia-mediated inflammation. Inflammatory cytokines level both in vitro (BV-2 cells) and in vivo (brain tissue from constructed IMI model and brain-isolated microglia) was detected. ECS levels were detected, and its effects on inflammations was also analyzed. Influence of microglia-mediated inflammation on neuron injury was analyzed. Moreover, the effects of ECS on protecting neuron injury were also analyzed. Our results showed that the levels of inflammatory cytokines including TNFα and IL-1β were higher while IKBα was lower in IMI model brain tissue, brain-isolated microglia and BV-2 cells compared to the control. Inflammation was activated in microglia, as well as the activation of ECS characterized by the increasing level of AEA and 2-AG. Furthermore, the activated microglia-mediated self-inflammation performed harmful influence on neurons via suppressing cell viability and inducing apoptosis. Moreover, ECS functioned as a protector on neuron injury though promoting cell proliferation and suppressing cell apoptosis which were caused by the activated BV-2 cells (LPS induced for 3 h). Our data suggested that ECS may play certain neuroprotective effects on microglia-mediated inflammations-induced IMI through anti-inflammatory function.

Propolis and swimming in the prevention of atherogenesis and left ventricular hypertrophy in hypercholesterolemic mice

AIMS

The present study verified the effect of propolis alone and its association with swimming in dyslipidemia, left ventricular hypertrophy and atherogenesis of hypercholesterolemic mice.

METHODS AND RESULTS

The experiments were performed in LDLr-/- mice, fed with high fat diet for 75 days, and were divided into four experimental groups (n=10): HL, sedentary, subjected to aquatic stress (5 min per day, 5 times per week); NAT submitted to a swimming protocol (1 hour per day, 5 times per week) from the 16th day of the experiment; PRO, sedentary, submitted to aquatic stress and which received oral propolis extract (70 uL/animal/day) from the 16th day of the experiment; HL+NAT+PRO, submitted to swimming and which received propolis as described above. After 75 days, blood was collected for analysis of serum lipids. The ratio between the ventricular weight (mg) and the animal weight (g) was calculated. Histological sections of the heart and aorta were processed immunohistochemically with anti-CD40L antibodies to evaluate the inflammatory process; stained with hematoxylin/eosin and picrosirius red to assess morphological and morphometric alterations. The HL animals showed severe dyslipidemia, atherogenesis and left ventricular hypertrophy, associated with a decrease in serum HDLc levels and subsequent development of cardiovascular inflammatory process, characterized by increased expression of CD40L in the left ventricle and aorta. Swimming and propolis alone and\or associated prevented the LVH, atherogenesis and arterial and ventricular inflammation, decreasing the CD40L expression and increasing the HDLc plasmatic levels.

CONCLUSION

Propolis alone or associated with a regular physical activity is beneficial in cardiovascular protection through anti-inflammatory action.

New frontiers for platelet CD154

The role of platelets extends beyond hemostasis. The pivotal role of platelets in inflammation has shed new light on the natural history of conditions associated with acute or chronic inflammation. Beyond the preservation of vascular integrity, platelets are essential to tissue homeostasis and platelet-derived products are already used in the clinics. Unanticipated was the role of platelets in the adaptative immune response, allowing a renewed conceptual approach of auto-immune diseases. Platelets are also important players in cancer growth and dissemination. Platelets fulfill most of their functions through the expression of still incompletely characterized membrane-bound or soluble mediators. Among them, CD154 holds a peculiar position, as platelets represent a major source of CD154 and as CD154 contributes to most of these new platelet attributes. Here, we provide an overview of some of the new frontiers that the study of platelet CD154 is opening, in inflammation, tissue homeostasis, immune response, hematopoiesis and cancer.

Interleukin 18 and extracellular matrix metalloproteinase inducer cross-regulation: implications in acute myocardial infarction

Circulating interleukin-18 (IL-18) is thought to promote atherosclerosis and cardiovascular complications such as plaque rupture. Atherosclerosis is also characterized by smooth muscle cell migration, a consequence of extracellular matrix (ECM) degradation regulated by metalloproteinases (MMPs). Because extracellular matrix metalloproteinase inducer (EMMPRIN) has been shown to promote plaque instability by inducing ECM degradation and MMP synthesis, we investigated whether a cross-regulatory interaction exists between IL-18 and EMMPRIN in human monocytes. EMMPRIN levels in monocytes were markedly greater in 20 patients with acute myocardial infarction (AMI) compared with 20 patients with stable angina pectoris or 20 healthy volunteers (control group). The levels of IL-18 and MMP-9 in serum were also significantly greater in the AMI group in comparison with the other 2 groups. IL-18 levels positively correlated with increased levels of EMMPRIN in monocytes. In vitro, the expression of EMMPRIN was increased in monocytes cultured with IL-18, and IL-18 secretion was augmented in monocytes cultured with EMMPRIN. Gene silencing of EMMPRIN by small interfering RNA reduced monocyte secretion of both IL-18 and MMP-9. In the present study, cross-regulation between IL-18 and EMMPRIN in monocytes was demonstrated. This interaction may amplify the inflammatory cascade and be responsible for increased monocytic MMP-9 serum levels in atherosclerosis, contributing to atherosclerotic plaque destabilization and subsequent AMI.

Serum soluble CD40 is associated with liver injury in patients with chronic hepatitis B

Soluble cluster of differentiation 40 (sCD40) is proteolytically cleaved from membrane-bound CD40 and binds to CD154, thereby inhibiting CD40-CD154-mediated immune responses. The aim of the present study was to clarify the role of sCD40 in chronic hepatitis B (CHB). The sCD40 levels in sera from 132 patients with CHB and 33 healthy individuals were retrospectively measured. sCD40 concentrations in patients with CHB were higher than those in healthy controls, and sCD40 levels correlated positively with serum levels of the liver dysfunction biomarkers alanine transaminase (ALT) and aspartate transaminase (AST). sCD40 concentrations increased with a rise in the severity of liver necroinflammation and fibrosis. Patients with >75% liver tissue staining positive for hepatitis B virus (HBV) antigen expression showed significantly lower sCD40 levels than those who stained negative for the HBV antigen. The area under the receiver operating characteristic curve of sCD40 was greater than that of ALT and AST; thus, sCD40 levels have a high diagnostic accuracy for detecting severe liver inflammation in patients with CHB, and could serve as an immunological marker of hepatic tissue injury.

TWEAK-Fn14 Cytokine-Receptor Axis: A New Player of Myocardial Remodeling and Cardiac Failure

Tumor necrosis factor (TNF) has been firmly established as a pathogenic factor in heart failure, a significant socio-economic burden. In this review, we will explore the role of other members of the TNF/TNF receptor superfamily (TNFSF/TNFRSF) in cardiovascular diseases (CVDs) focusing on TWEAK and its receptor Fn14, new players in myocardial remodeling and heart failure. The TWEAK/Fn14 pathway controls a variety of cellular activities such as proliferation, differentiation, and apoptosis and has diverse biological functions in pathological mechanisms like inflammation and fibrosis that are associated with CVDs. Furthermore, it has recently been shown that the TWEAK/Fn14 axis is a positive regulator of cardiac hypertrophy and that deletion of Fn14 receptor protects from right heart fibrosis and dysfunction. We discuss the potential use of the TWEAK/Fn14 axis as biomarker for CVDs as well as therapeutic target for future treatment of human heart failure based on supporting data from animal models and in vitro studies. Collectively, existing data strongly suggest the TWEAK/Fn14 axis as a potential new therapeutic target for achieving cardiac protection in patients with CVDs.

Matrix metalloproteinases in coronary artery disease

Matrix metalloproteinases (MMP) are a family of zinc-containing endoproteinases that degrade extracellular matrix (ECM) components. MMP have important roles in the development, physiology and pathology of cardiovascular system. Metalloproteases also play key roles in adverse cardiovascular remodeling, atherosclerotic plaque formation and plaque instability, vascular smooth muscle cell (SMC) migration and restenosis that lead to coronary artery disease (CAD), and progressive heart failure. The study of MMP in developing animal model cardiovascular systems has been helpful in deciphering numerous pathologic conditions in humans. Increased peripheral blood MMP-2 and MMP-9 in acute coronary syndrome (ACS) may be useful as noninvasive tests for detection of plaque vulnerability. MMP function can be modulated by certain pharmacological drugs that can be exploited for treatment of ACS. CAD is a polygenic disease and hundreds of genes contribute toward its predisposition. A large number of sequence variations in MMP genes have been identified. Case-control association studies have highlighted their potential association with CAD and its clinical manifestations. Although results thus far are inconsistent, meta-analysis has demonstrated that MMP-3 Glu45Lys and MMP-9 1562C/T gene polymorphisms were associated with CAD risk.

The role of hypoxia in orthodontic tooth movement

Orthodontic forces are known to have various effects on the alveolar process, such as cell deformation, inflammation, and circulatory disturbances. Each of these conditions affecting cell differentiation, cell repair, and cell migration, is driven by numerous molecular and inflammatory mediators. As a result, bone remodeling is induced, facilitating orthodontic tooth movement. However, orthodontic forces not only have cellular effects but also induce vascular changes. Orthodontic forces are known to occlude periodontal ligament vessels on the pressure side of the dental root, decreasing the blood perfusion of the tissue. This condition is accompanied by hypoxia, which is known to either affect cell proliferation or induce apoptosis, depending on the oxygen gradient. Because upregulated tissue proliferation rates are often accompanied by angiogenesis, hypoxia may be assumed to fundamentally contribute to bone remodeling processes during orthodontic treatment.

Soluble CD40 ligand impairs the anti-platelet function of peripheral blood angiogenic outgrowth cells via increased production of reactive oxygen species

Adult peripheral blood angiogenic early outgrowth cells (EOCs), also known as early endothelial progenitor cells, interact with other blood and vascular cells and may regulate atherothrombosis. We have previously shown that endothelial progenitor cells inhibit platelet function and thrombus formation. The CD40L/CD40 axis is a thrombo- inflammatory mediator that affects platelet and endothelial functions. It has been shown that EOCs express CD40, whereas platelets represent the major source of its soluble ligand (sCD40L), which impairs EOC function.We aimed to test the hypothesis that the sCD40L/CD40 axis affects the anti-platelet function of EOCs. Human peripheral blood mononuclear cell-derived EOCs in culture inhibited platelet aggregation. Pre-treatment of EOCs with sCD40L reduced their inhibitory effect on platelet aggregation in a CD40-dependent manner. EOCs viability and release of the anti-aggregating agents, prostacyclin and nitric oxide, were not affected by sCD40L. However, production of reactive oxygen species (ROS) was increased in sCD40L-treated EOCs. Blockade of ROS reversed the effects of sCD40L-treated EOCs on platelet aggregation. This study reveals that the sCD40L/CD40 axis impairs the anti-platelet properties of EOCs through increased production of ROS. These data may explain the link between elevated levels of sCD40L, impaired activity of EOCs and enhanced platelet reactivity, and consequently the occurrence of atherothrombotic disease.

Immune and inflammatory cell involvement in the pathology of idiopathic pulmonary arterial hypertension

RATIONALE

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction and vascular remodeling. Recent studies have revealed that immune and inflammatory responses play a crucial role in pathogenesis of idiopathic PAH.

OBJECTIVES

To systematically evaluate the number and cross-sectional distribution of inflammatory cells in different sizes of pulmonary arteries from explanted lungs of patients with idiopathic PAH versus healthy donor lungs and to demonstrate functional relevance by blocking stromal-derived factor-1 by the Spiegelmer NOX-A12 in monocrotaline-induced pulmonary hypertension in rats.

METHODS

Immunohistochemistry was performed on lung tissue sections from patients with idiopathic PAH and healthy donors. All positively stained cells in whole-lung tissue sections, surrounding the vessels, and in the different compartments of the vessels were counted. To study the effects of blocking SDF-1, rats with monocrotaline-induced pulmonary hypertension were treated with NOX-A12 from Day 21 to Day 35 after monocrotaline administration.

MEASUREMENTS AND MAIN RESULTS

We found a significant increase of the perivascular number of macrophages (CD68(+)), macrophages/monocytes (CD14(+)), mast cells (toluidine blue(+)), dendritic cells (CD209(+)), T cells (CD3(+)), cytotoxic T cells (CD8(+)), and helper T cells (CD4(+)) in vessels of idiopathic PAH lungs compared with control subjects. FoxP3(+) mononuclear cells were significantly decreased. In the monocrotaline model, the NOX-A12-induced reduction of mast cells, CD68(+) macrophages, and CD3(+) T cells was associated with improvement of hemodynamics and pulmonary vascular remodeling.

CONCLUSIONS

Our findings reveal altered perivascular inflammatory cell infiltration in pulmonary vascular lesions of patients with idiopathic pulmonary arterial hypertension. Targeting attraction of inflammatory cells by blocking stromal-derived factor-1 may be a novel approach for treatment of PAH.

The pathophysiology of endothelial function in pregnancy and the usefulness of endothelial markers

AIM

The aim of this study was to assess coagulation markers of endothelial damage and examine new markers of endothelial activation such as matrix metalloproteinases (MMPs) in a group of healthy pregnant women. Matrix metalloproteinase (MMP)-2, in particular, plays a major role in the degradation of the extracellular matrix confirming its essential function in both the survival (angiogenesis) and death of endothelial cells. Detection of specific coagulation factors, mainly released from the vascular endothelium such as vWF, sTM (soluble thrombomodulin) and ePCR (endothelial protein C receptor) and factors dependent on endothelial activation such as t-PA and PAI-1, could provide information on possible endothelial dysfunction and help differentiate pregnant patients with an altered thrombotic state.

METHODS

Healthy pregnant women underwent complete assessment for endothelial damage (as vWF, vWF activity, sTM, ePCR, EMP, MMP-2, MMP-9 and TIMP-2) using the ELISA and other methods.

RESULTS AND CONCLUSIONS

The results show that endothelial activation during pregnancy is different from that in other pathological conditions involving endothelial damage and typically characterized by higher levels of both coagulation endothelial markers and MMPs. In pregnancy, changes in extracellular matrix composition and matrix metalloproteinase activity also occur and promote vascular remodeling but, only in the uterus. Predisposing risk factors for epithelial dysfunction, and vascular mediators associated with vascular remodeling must be assessed from concentrations in whole blood. The levels of MMPs are not increased in the circulation and the local situation in the uterus cannot be monitored this way. However, MMP-2 processes and modulates the functions of many other vasoactive and pro-inflammatory molecules including adrenomedullin, big endothelin-1, calcitonin gene-related peptide, CCL7/MCP-3, CXCL12/SDF-1, galectin-3, IGFBP-3, IL-1 Beta, S100A8, and S100A9. These molecules represent new potential molecular markers of endothelial damage during pregnancy.

Matrix metalloproteinase inhibition therapy for vascular diseases

The matrix metalloproteinases (MMPs) are 23 secreted or cell surface proteases that act together and with other protease classes to turn over the extracellular matrix, cleave cell surface proteins and alter the function of many secreted bioactive molecules. In the vasculature MMPs influence the migration proliferation and apoptosis of vascular smooth muscle, endothelial cells and inflammatory cells, thereby affecting intima formation, atherosclerosis and aneurysms, as substantiated in clinical and mouse knockout and transgenic studies. Prominent counterbalancing roles for MMPs in tissue destruction and repair emerge from these experiments. Naturally occurring tissue inhibitors of MMPs (TIMPs), pleiotropic mediators such as tetracyclines, chemically-synthesised small molecular weight MMP inhibitors (MMPis) and inhibitory antibodies have all shown effects in animal models of vascular disease but only doxycycline has been evaluated extensively in patients. A limitation of broad specificity MMPis is that they prevent both matrix degradation and tissue repair functions of different MMPs. Hence MMPis with more restricted specificity have been developed and recent studies in models of atherosclerosis accurately replicate the phenotypes of the corresponding gene knockouts. This review documents the established actions of MMPs and their inhibitors in vascular pathologies and considers the prospects for translating these findings into new treatments.

Platelet soluble CD40L and matrix metalloproteinase 9 activity are proinflammatory mediators in Behçet disease patients

Platelets are the major source of plasma-soluble CD40L (sCD40L), an important inflammatory mediator. This study explored the impact of platelet-derived sCD40L on Behçet disease (BD), an autoinflammatory vasculitis. We also searched for influences by platelet matrix metalloproteinases (MMP) -2 and MMP-9, implicated in several inflammatory diseases, on CD40L shedding from platelet membrane. Platelet activation were studied by flow cytometry and aggregometry, surface expression of CD40L and platelet-leukocyte aggregates by flow cytometry, sCD40L by ELISA, cellular CD40L and CD40 levels by Western blot and MMPs activity by gelatin zymography. The effect of sCD40L on MMP9 expression was studied in cultured MEG-01 cells. Plasma and platelet-released sCD40L levels were higher in BD patients. No differences in platelet activation and in platelet-leukocyte aggregates formation were observed between BD patients and controls. Plasma and platelet MMP-9 levels were increased in BD patients, whereas there was no difference in platelet MMP-2 activity. Since a correlation between plasma sCD40L and platelet MMP-9 activity was observed, we studied the influence of sCD40L on MMP-9 levels in the megakaryoblastic cell line MEG-01. Treatment of MEG-01 cells with recombinant sCD40L increased MMP-9 but did not change MMP-2 levels. In conclusion, sCD40L release from platelets was mediated by MMP-9, and MMP-9 expression was in turn upregulated by sCD40L in the MEG-01 cell line. We conclude that platelets and megakaryocytes might participate in a positive feedback loop occurring between sCD40L and MMP-9 which would contribute to the proinflammatory state observed in BD.

CD40/CD40L interaction induces E-selectin dependent leukocyte adhesion to human endothelial cells and inhibits endothelial cell migration

BACKGROUND

CD40 is a receptor expressed on a wide range of cells such as leukocytes and endothelial cells (EC). As a member of the tumor necrosis factor (TNF) superfamily the activation of CD40 by CD40-ligand (CD40L) plays a crucial role for the development and progression of a variety of inflammatory processes including atherosclerosis. The aim of the present study was to investigate the effect of CD40/CD40L interaction on leukocyte adhesion to the endothelium and on endothelial cell migration.

METHODS AND RESULTS

Human umbilical vein endothelial cells (HUVEC) were stimulated with either stable transfectants of mouse myeloma cells expressing the CD40L or wild type cells (4 h). Subsequently adhesion of leukocytes expressing Sialyl Lewis X, the counterpart for E-selectin (HL60 cells), was measured under shear stress (2-2.6 dyne/cm(2)) using a flow chamber adhesion assay. Stimulation of CD40 led to a significant increase of E-selectin dependent adhesion of leukocytes to the endothelium. Incubation of cells with either the CD40L blocking antibody TRAP-1 or the E-selectin blocking antibody BBA2 during CD40 stimulation completely abolished adhesion of leukocytes to HUVEC. Similar results were found in human cardiac microvasculature endothelial cells (HCMEC). In contrast stimulation of CD40 had no effect on adhesion of L-selectin expressing NALM6-L cells. Furthermore, CD40/CD40L interaction abrogated VEGF-induced migration of HUVEC compared to non-stimulated controls. In comparison experiments, stimulation of endothelial cells with VEGF led to a significant phosphorylation of ERK1/2, Akt, and eNOS. Stimulation of endothelial CD40 had no effect on VEGF-induced phosphorylation of ERK1/2. However, VEGF-induced activation of Akt and eNOS was reduced to baseline levels when endothelial CD40 was stimulated.

CONCLUSION

CD40/CD40L interaction induces E-selectin dependent adhesion of leukocytes to human endothelial cells and reduces endothelial cell migration by inhibiting the Akt/eNOS signaling pathway.

Matrix metalloproteinases in cytotoxic lymphocytes impact on tumour infiltration and immunomodulation

To efficiently combat solid tumours, endogenously or adoptively transferred cytotoxic T cells and natural killer (NK) cells, need to leave the vasculature, traverse the interstitium and ultimately infiltrate the tumour mass. During this locomotion and migration in the three dimensional environment many obstacles need to be overcome, one of which is the possible impediment of the extracellular matrix. The first and obvious one is the sub-endothelial basement membrane but the infiltrating cells will also meet other, both loose and tight, matrix structures that need to be overridden. Matrix metalloproteinases (MMPs) are believed to be one of the most important endoprotease families, with more than 25 members, which together have function on all known matrix components. This review summarizes what is known on synthesis, expression patterns and regulation of MMPs in cytotoxic lymphocytes and their possible role in the process of tumour infiltration. We also discuss different functions of MMPs as well as the possible use of other lymphocyte proteases for matrix degradation.

Enhanced levels of soluble CD40 ligand exacerbate platelet aggregation and thrombus formation through a CD40-dependent tumor necrosis factor receptor-associated factor-2/Rac1/p38 mitogen-activated protein kinase signaling pathway

OBJECTIVE

CD40 ligand is a thromboinflammatory molecule that predicts cardiovascular events. Platelets constitute the major source of soluble CD40 ligand (sCD40L), which has been shown to influence platelet activation, although its exact functional impact on platelets and the underlying mechanisms remain undefined. We aimed to determine the impact and the signaling mechanisms of sCD40L on platelets.

METHODS AND RESULTS

sCD40L strongly enhances platelet activation and aggregation. Human platelets treated with a mutated form of sCD40L that does not bind CD40, and CD40(-/-) mouse platelets failed to elicit such responses. Furthermore, sCD40L stimulation induces the association of the tumor necrosis factor receptor-associated factor-2 with platelet CD40. Notably, sCD40L primes platelets through activation of the small GTPase Rac1 and its downstream target p38 mitogen-activated protein kinase, which leads to platelet shape change and actin polymerization. Moreover, sCD40L exacerbates thrombus formation and leukocyte infiltration in wild-type mice but not in CD40(-/-) mice.

CONCLUSIONS

sCD40L enhances agonist-induced platelet activation and aggregation through a CD40-dependent tumor necrosis factor receptor-associated factor-2/Rac1/p38 mitogen-activated protein kinase signaling pathway. Thus, sCD40L is an important platelet primer predisposing platelets to enhanced thrombus formation in response to vascular injury. This may explain the link between circulating levels of sCD40L and cardiovascular diseases.

CD40/CD40L signaling and its implication in health and disease

CD40, a transmembrane receptor of the tumor necrosis factor gene superfamily is expressed on a variety of cells, such as monocytes, B-cells, antigen presenting cells, endothelial, smooth muscle cells, and fibroblasts. The interaction between CD40 and CD40 ligand (CD40L) enhances the expression of cytokines, chemokines, matrix metalloproteinases, growth factors, and adhesion molecules, mainly through the stimulation of nuclear factor kappa B. The aim of this review is to summarize the molecular and cellular characteristics of CD40 and CD40L, the mechanisms that regulate their expression, the cellular responses they stimulate and finally their implication in the pathophysiology of inflammatory and autoimmune diseases.

High plasma levels of CD40 are associated with low coenzyme Q and vitamin E content of low‐density lipoprotein in healthy men

OBJECTIVE

There is a growing body of evidence to suggest that low-density lipoprotein (LDL) cholesterol, inflammation and oxidative stress are pivotal in the development of cardiovascular disease, but their interconnections are not well known. The objective of this study was to determine whether immunological activation, reflected by the plasma levels of soluble CD40 (sCD40), interleukin (IL)-1beta, tumor necrosis factor-alpha and IL-6 are associated with the antioxidant potential of LDL particles or with common lipid, immunological or thrombotic markers in 51 young healthy men.

MATERIAL AND METHODS

We determined the coenzyme Q level from an oxidized LDL fraction, obtaining the concentration for ubiquinone, which indicates total coenzyme Q levels.

RESULTS

The plasma level of sCD40 was negatively correlated with LDL ubiquinone (r=-0.45, p=0.001) and E vitamin (r=-0.37, p=0.008) and positively correlated with plasma concentration of plasminogen activator inhibitor-1 (PAI-1, r=0.52, p=0.002) and caspase-1 (r=0.40, p=0.004). No correlation was detected between sCD40 and plasma lipid or C-reactive protein concentrations. As sCD40 was strongly correlated with the content of LDL ubiquinone and vitamin E, their values were compared according to groups formed by sCD40 tertiles. Analysis of variance showed that there were significant differences in LDL ubiquinone (p<0.0001) and vitamin E (p=0.004) concentrations between sCD40 tertiles.

CONCLUSIONS

The data indicate that increased activation of the CD40 system is related to low levels of LDL ubiquinone and vitamin E. This suggests that chronic or increased immunological activation may consume the antioxidant potential of LDL particles.

Quantum dot mediated imaging of atherosclerosis

The progression of atherosclerosis is associated with leukocyte infiltration within lesions. We describe a technique for the ex vivo imaging of cellular recruitment in atherogenesis which utilizes quantum dots (QD) to color-code different cell types within lesion areas. Spectrally distinct QD were coated with the cell-penetrating peptide maurocalcine to fluorescently-label immunomagnetically isolated monocyte/macrophages and T lymphocytes. QD-maurocalcine bioconjugates labeled both cell types with a high efficiency, preserved cell viability, and did not perturb native leukocyte function in cytokine release and endothelial adhesion assays. QD-labeled monocyte/macrophages and T lymphocytes were reinfused in an ApoE(-/-) mouse model of atherosclerosis and age-matched controls and tracked for up to four weeks to investigate the incorporation of cells within aortic lesion areas, as determined by oil red O (ORO) and immunofluorescence ex vivo staining. QD-labeled cells were visible in atherosclerotic plaques within two days of injection, and the two cell types colocalized within areas of subsequent ORO staining. Our method for tracking leukocytes in lesions enables high signal-to-noise ratio imaging of multiple cell types and biomarkers simultaneously within the same specimen. It also has great utility in studies aimed at investigating the role of distinct circulating leukocyte subsets in plaque development and progression.

Serum matrix metalloprotease-1 and vascular endothelial growth factor--a predict cardiac allograft rejection

Cardiac allograft rejection is currently diagnosed from endomyocardial biopsies (EMB) that are invasive and impractical to repeat. A serological marker could facilitate rejection monitoring and minimize EMB-associated risks. We investigated the relation of serum matrix metalloprotease (MMP)-1 and vascular endothelial growth factor (VEGF)-A concentrations to cardiac allograft rejection, using 1176 EMBs and serum samples obtained from 208 recipients. Acute cellular rejection was diagnosed in 186 EMBs. Mean week 1 and week 2 serum MMP-1 concentrations predicted rejection (p = 0.001, AUC = 0.80). At the optimal cut-off level of >or=7.5 ng/mL, MMP-1 predicted rejection with 82% sensitivity and 72% specificity. Initial serum MMP-1 <5.3 ng/mL (lowest quartile) was associated with rejection-free outcome in 80% of patients. Both MMP-1 (p < 0.001, AUC = 0.67-0.75) and VEGF-A (p < 0.01, AUC = 0.62-0.67) predicted rejection on the next EMB, while rejection at EMB was identified only by VEGF-A (p < 0.02, AUC = 0.70-0.77). Patients receiving combined cyclosporine-A and everolimus had the lowest serum MMP-1 concentrations. While serum MMP-1 predicts rejection-free outcome and VEGF-A identifies rejection on EMB, both markers predict rejection in follow-up of cardiac transplant recipients. Combination of serum MMP-1 and VEGF-A concentration may be a noninvasive prognostic marker of cardiac allograft rejection, and could have important implications for choice of surveillance and immunosuppression protocols.

CD40 ligand+ microparticles from human atherosclerotic plaques stimulate endothelial proliferation and angiogenesis a potential mechanism for intraplaque neovascularization

OBJECTIVES

Our goal was to demonstrate that microparticles (MPs) are the endogenous signal leading to neovessel formation through CD40 ligation in human atherosclerotic plaques.

BACKGROUND

Vulnerable atherosclerotic plaques prone to rupture are characterized by an increased number of vasa vasorum and frequent intraplaque hemorrhage. Although inflammatory cytokines, growth factors, or CD40/CD40 ligand (CD40L) are possible candidates, the mechanism of atherosclerotic plaque neovascularization remains unknown. Atherosclerotic plaques contain large amounts of membrane-shed submicron MPs released after cell activation or apoptosis.

METHODS

Microparticles were isolated from endarterectomy specimens surgically obtained from 26 patients and characterized by phosphatidylserine exposure and specific markers of cellular origin.

RESULTS

Plaque MPs increased both endothelial proliferation assessed by (3)H-thymidine incorporation and cell number and stimulated in vivo angiogenesis in Matrigel (BD Biosciences, San Diego, California) assays performed in wild-type and BalbC/Nude mice, whereas circulating MPs had no effect. Microparticles from symptomatic patients expressed more CD40L and were more potent in inducing endothelial proliferation, when compared with asymptomatic plaque MPs. Most of CD40L+ MPs (93%) isolated from human plaques were of macrophage origin. Microparticle-induced endothelial proliferation was impaired by CD40L or CD40-neutralizing antibodies and abolished after endothelial CD40-ribonucleic acid silencing. In addition, the proangiogenic effect of plaque MPs was abolished in Matrigel assays performed in the presence of CD40L-neutralizing antibodies or in CD40-deficient mice.

CONCLUSIONS

These results demonstrate that MPs isolated from human atherosclerotic lesions express CD40L, stimulate endothelial cell proliferation after CD40 ligation, and promote in vivo angiogenesis. Therefore, MPs could represent a major determinant of intraplaque neovascularization and plaque vulnerability.

The effects of daily irradiation with polychromatic visible polarized light on human lymphocyte populations

OBJECTIVE

The goal of this randomized, placebo controlled, double-blind study was to investigate the effects of transcutaneous irradiation with polychromatic visible polarized light (540-780 nm; 68% polarization; power density 3.0 E-10 W/cm(2)) on a subset population of human lymphocytes using flow cytometry.

BACKGROUND DATA

The biomodulation and therapeutic effects of visible light of different wavelengths are well known, but the immunological effects of polychromatic visible polarized light have not been investigated sufficiently.

METHODS

Before and after 28 consecutive days of irradiation, blood samples were collected from the subjects and the population count of the lymphocyte subset was measured.

RESULTS

The absolute count of total lymphocytes, CD3(+) lymphocytes, and CD3(+)CD4(+) lymphocytes increased by 7% (p = 0.023), 9% (p = 0.058), and 13% (p = 0.021), respectively. Yet the absolute count of WBCs, CD3(+)CD8(+), CD19(+), and CD16(+)56(+) lymphocytes did not change significantly.

CONCLUSION

The application of polychromatic visible polarized light with the aforementioned features increases the CD3(+)CD4(+) lymphocyte population. It is suggested that this regimen may be useful for the promotion of natural defenses in cell-mediated immunity.

Soluble CD40 ligand induces endothelial dysfunction in human and porcine coronary artery endothelial cells

The purpose of this study was to determine the effects and mechanisms of sCD40L on endothelial dysfunction in both human coronary artery endothelial cells (HCAECs) and porcine coronary artery rings. HCAECs treated with sCD40L showed significant reductions of endothelial nitric oxide synthase (eNOS) mRNA and protein levels, eNOS mRNA stability, eNOS enzyme activity, and cellular NO levels, whereas superoxide anion (O(2)(-)) production was significantly increased. sCD40L enhanced eNOS mRNA 3'UTR binding to cytoplasmic molecules and induced a unique expression pattern of 95 microRNAs. sCD40L significantly decreased mitochondrial membrane potential, and catalase and SOD activities, whereas it increased NADPH oxidase (NOX) activity. sCD40L increased phosphorylation of MAPKs p38 and ERK1/2 as well as IkappaBalpha and enhanced NF-kappaB nuclear translocation. In porcine coronary arteries, sCD40L significantly decreased endothelium-dependent vasorelaxation and eNOS mRNA levels, whereas it increased O(2)(-) levels. Antioxidant seleno-l-methionine; chemical inhibitors of p38, ERK1/2, and mitochondrial complex II; as well as dominant negative mutant forms of IkappaBalpha and NOX4 effectively blocked sCD40L-induced eNOS down-regulation in HCAECs. Thus, sCD40L reduces eNOS levels, whereas it increases oxidative stress through the unique molecular mechanisms involving eNOS mRNA stability, 3'UTR-binding molecules, microRNAs, mitochondrial function, ROS-related enzymes, p38, ERK1/2, and NF-kappaB signal pathways in endothelial cells.

Reactive oxygen species and endothelial activation

Endothelial activation refers to a specific change in endothelial phenotype, characterized most notably by an increase in endothelial-leukocyte interactions and permeability, which is pivotal to inflammatory responses in both physiologic and pathologic settings. An increasing body of evidence indicates an important role for reactive oxygen species (ROS)-mediated modulation of signal-transduction pathways in many of the processes involved in endothelial activation. ROS generated by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family of enzymes may be especially important in this regard. We discuss the evidence implicating redox signaling pathways in the molecular and cellular processes underlying endothelial activation and the role in cardiovascular diseases, and also provide a detailed description of NADPH oxidase regulation in endothelial cells, in view of its likely importance in this context.

CD154-stimulated GM-CSF release by vascular smooth muscle cells elicits monocyte activation--role in atherogenesis

During the early phase of atherosclerosis, T cells and monocytes attach to and migrate through the endothelium into the vessel wall. To provide an insight into the potential cross talk between T cells and smooth muscle cells (SMC) in atherogenesis, we investigated changes in gene expression caused by CD40 ligation in cultured vascular SMC and their consequences for monocyte activation. CD40 expression in human-cultured SMC was induced by 24-h treatment with tumor necrosis factor-alpha plus interferon-gamma followed by 12-h exposure to mouse myeloma cells stably expressing human CD154 or the corresponding control cells. DNA microarray analysis (Affymetrix HG-U952A chip) indicated 33 up-regulated genes in three individual experiments of which 19 encoded pro-inflammatory adhesion molecules, cytokines, chemokines, and receptors. One functional consequence of this change in gene expression was an activation of transformed human promonocytic-1 monocytes exposed to the conditioned medium of the stimulated SMC. Subsequent antibody neutralization experiments identified granulocyte-macrophage colony-stimulating factor (GM-CSF) as the SMC-derived cytokine responsible for this effect. Thus, vascular SMC-like endothelial cells appear to contribute to the maintenance of an inflammatory response in the atherosclerotic vessel wall upon CD40-CD154 co-stimulation. Among 19 up-regulated pro-inflammatory gene products, GM-CSF plays an important role in SMC-dependent monocyte activation.

High serum levels of soluble CD40-L in patients with undifferentiated nasopharyngeal carcinoma: pathogenic and clinical relevance

BACKGROUND

Engagement of CD40 promotes survival of undifferentiated nasopharyngeal carcinoma (UNPC) cells and similar effects are induced by the EBV oncoprotein LMP-1 that is expressed in a fraction of cases. Considering that CD40 may be activated also by the soluble isoform of CD40L (sCD40L), we investigated the serum levels of sCD40L in a series of 61 UNPC patients from Italy, a non-endemic area for this disease.

RESULTS

At diagnosis, serum samples of UNPC patients contained significantly higher levels of sCD40L than age-matched healthy controls (p < 0.001). High levels of sCD40L (i.e., >18 ng/ml) were more frequently found in patients <40 years of age (p = 0.03) and with distant metastases at presentation (p = 0.03). Serum levels of sCD40L were inversely associated with the expression of the EBV oncoprotein LMP-1 (p = 0.03), which mimics a constitutively activated CD40. The amount of sCD40L decreased in a fraction of patients treated with local radiotherapy alone. Moreover, CD40L+ lymphoid cells admixed to neoplastic UNPC cells were detected in cases with high serum levels of sCD40L, suggesting that sCD40L is probably produced within the tumor mass.

CONCLUSION

sCD40L may contribute to CD40 activation in UNPC cells, particularly of LMP-1-negative cases, further supporting the crucial role of CD40 signalling in the pathogenesis of UNPC. sCD40L levels may be useful to identify UNPC patients with occult distant metastases at presentation.

Imbalance of Matrix Metalloproteinase-1 and Tissue Inhibitor of Metalloproteinases: A Novel Approach for Explaining the Parenchymal Liquefaction of the Septic Spleen?

OBJECTIVE

The causal pathophysiological mechanisms involved in the parenchymal liquefaction of the septic spleen are still far from clear. The balance between matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), is largely responsible for the remodelling of tissues. Deregulation of this balance is a characteristic of extensive tissue degradation in certain chronic inflammatory diseases.

METHODS

This study focuses on a search for alterations in the balance between MMP-1 (interstitial collagenase) and TIMP-1 by means of immunostaining, by immunoblotting, and by gel zymography.

RESULTS

We found a deregulation of the balance between MMP-1 and TIMP-1 in the septic spleen in favor of the active form of MMP-1.

CONCLUSION

Our findings suggest that active MMP-1 is involved in collagenolytic extracellular matrix breakdown in the septic spleen.

Loss of flow induces leukocyte-mediated MMP/TIMP imbalance in dynamic in vitro blood-brain barrier model: role of pro-inflammatory cytokines

There is substantial evidence linking blood-brain barrier (BBB) failure during cerebral ischemia to matrix metalloproteinases (MMP). BBB function may be affected by loss of shear stress under normoxia/normoglycemia, as during cardiopulmonary bypass procedures. The present study used an in vitro flow-perfused BBB model to analyze the individual contributions of flow, cytokine levels, and circulating blood leukocytes on the release/activity of MMP-9, MMP-2, and their endogenous inhibitors, the tissue inhibitors of MMPs (TIMPs), TIMP-1, and TIMP-2. The presence of circulating blood leukocytes under normoxic/normoglycemic flow cessation/reperfusion significantly increased the luminal levels of MMP-9 and activity of MMP-2, accompanied by partial reduction of TIMP-1, complete reduction of TIMP-2 and increased BBB permeability. These changes were not observed during constant flow with circulating blood leukocytes, or after normoxic/normoglycemic or hypoxic/hypoglycemic flow cessation/reperfusion without circulating blood leukocytes. The addition of anti-IL-6 or anti-TNF-α antibody in the lumen before reperfusion suppressed the levels of MMP-9 and activity of MMP-2, had no effect on TIMP-1, and completely restored TIMP-2 and BBB integrity. Injection of TIMP-2 in the lumen before reperfusion prevented the activation of MMP-2 and BBB permeability. These data indicate that blood leukocytes and loss of flow are major factors in the activation of MMP-2, and that cytokine-mediated differential regulation of TIMP-1 and TIMP-2 may contribute significantly to BBB failure.

Soluble CD40 Ligand Levels during Controlled Ovarian Hyperstimulation – A Possible Culprit of Systemic Inflammation

AIM

To investigate the behavior and association of serum sex-steroids and serum CD40 ligand in patients undergoing controlled ovarian hyperstimulation (COH) for in vitro fertilization (IVF).

DESIGN

Prospective, observational study.

SETTING

The IVF unit of an academic medical center.

PATIENTS AND METHODS

Blood was drawn three times during the COH cycle from 17 patients undergoing the long gonadotropin-releasing hormone-analog protocol: (i) day on which adequate suppression was obtained (Day-S); (ii) day of or prior to administration of human chorionic gonadotropin (Day-hCG); and (iii) day of ovum pick-up (Day-OPU). Levels of sex steroids and serum CD40 ligand were compared among the three time points.

RESULTS

During gonadotropin treatment, serum ovarian sex steroids (estradiol, progesterone, free testosterone and androstenedione) significantly increased while CD40 ligand levels nonsignificantly decreased. After hCG administration, there was a significant increase in the levels of serum CD40 ligand, ovarian androgens, and progesterone, with a significant decrease in estradiol levels. No correlations were observed between CD40 ligand and ovarian sex-steroid levels or other treatment variables.

CONCLUSION

The administration of hCG leads to activation of systemic inflammation, as reflected by CD40 ligand levels. This, in turn, may lead to the development of ovarian hyperstimulation syndrome via several mechanisms, including an increase in several angiogenic factors.

Differential regulation of soluble and membrane CD40L proteins in T cells

CD40 ligand is an important immunoregulatory protein expressed by T cells. This protein exists as two isoforms, a membrane glycoprotein and a truncated soluble form. Here we demonstrate that membrane and soluble CD40L (sCD40L) are differentially regulated depending upon the activation stimulus. In T cell receptor activated cells, both membrane and sCD40L proteins are expressed and CD28 costimulation further increases their expression. The dissection of TCR generated signals into calcium and PKC-dependent pathways demonstrates that calcium is sufficient to induce membrane CD40L yet insufficient for sCD40L. In contrast, sCD40L is preferentially induced by PKC. Moreover, sCD40L production is blocked by Zn(2+)-dependent metalloproteinase inhibitors while membrane CD40L is concurrently increased. This profile suggests the potential involvement of the ADAM-10 protease which was subsequently shown to cleave membrane CD40L to generate sCD40L. Given the role of sCD40L in numerous disease pathologies and its ability to activate proximal and distal immune responses, the regulated cleavage of CD40L may likely contribute to disease mechanisms.

Cyclic strain-mediated matrix metalloproteinase regulation within the vascular endothelium: a force to be reckoned with

The vascular endothelium is a dynamic cellular interface between the vessel wall and the bloodstream, where it regulates the physiological effects of humoral and biomechanical stimuli on vessel tone and remodeling. With respect to the latter hemodynamic stimulus, the endothelium is chronically exposed to mechanical forces in the form of cyclic circumferential strain, resulting from the pulsatile nature of blood flow, and shear stress. Both forces can profoundly modulate endothelial cell (EC) metabolism and function and, under normal physiological conditions, impart an atheroprotective effect that disfavors pathological remodeling of the vessel wall. Moreover, disruption of normal hemodynamic loading can be either causative of or contributory to vascular diseases such as atherosclerosis. EC-matrix interactions are a critical determinant of how the vascular endothelium responds to these forces and unquestionably utilizes matrix metalloproteinases (MMPs), enzymes capable of degrading basement membrane and interstitial matrix molecules, to facilitate force-mediated changes in vascular cell fate. In view of the growing importance of blood flow patterns and mechanotransduction to vascular health and pathophysiology, and considering the potential value of MMPs as therapeutic targets, a timely review of our collective understanding of MMP mechanoregulation and its impact on the vascular endothelium is warranted. More specifically, this review primarily summarizes our current knowledge of how cyclic strain regulates MMP expression and activation within the vascular endothelium and subsequently endeavors to address the direct and indirect consequences of this on vascular EC fate. Possible relevance of these phenomena to vascular endothelial dysfunction and pathological remodeling are also addressed.

CD40 ligand increases expression of its receptor CD40 in human coronary artery endothelial cells

BACKGROUND

Recently, CD40 ligand (CD40L) and its receptor CD40 have been implicated in atherosclerosis. Clinical data showed that elevated CD40L levels are associated with a high risk of cardiovascular events. The aim of this study was to investigate whether CD40L could affect the expression of its membrane receptor CD40 as a feedback mechanism by which CD40L could enhance its functions in human coronary artery endothelial cells (HCAECs).

METHODS

The HCAECs were treated with human soluble CD40L, and the messenger RNA (mRNA) and protein levels of CD40 were determined by real-time polymerase chain reaction and Western blot analysis, respectively. The specific effect of CD40L was confirmed by a blocking experiment with antibody against CD40L. Involvements of oxidative stress and mitogen-activated protein kinases (MAPKs) were also studied with antioxidant seleno-L-methionine (SeMet) and MAPK inhibitors such as extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor.

RESULTS

When HCAECs were cultured with CD40L (5 microg/mL) for 24 hours, CD40 mRNA levels were increased by 79% compared with controls (P < .05). Similarly, Western blot analysis showed an 80% increase in CD40 protein levels (P < .05). The CD40L-induced increase in CD40 mRNA levels were blocked specifically by anti-CD40L antibody. Antioxidant SeMet and specific ERK1/2 inhibitor (PD98059) also effectively blocked CD40L-induced CD40 mRNA increase.

CONCLUSIONS

These data demonstrate that clinically relevant concentration of CD40L increased the expression of its receptor CD40 in HCAECs. The CD40L-induced upregulation of CD40 may be mediated by oxidative stress and ERK1/2 activation. This study suggests a new mechanism by which CD40L could enhance its biologic functions in the vascular system and contribute to endothelial dysfunction and vascular disease.