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

Oxidative post-translational modification of catalase confers salt stress acclimatization by regulating H2O2 homeostasis in Malus hupehensis

Reactive oxygen species (ROS) play an essential role as both signaling molecule and damage agent during salt stress. As a signaling molecule, proper accumulation of H2O2 is crucial to trigger stress response and enhance stress tolerance. However, the dynamic regulation mechanism of H2O2 remains unclear. Here, we show that MhCAT2 (catalase 2 in Malus hupehensis) undergoes oxidative modification in an O2•--dependent manner and that oxidation at His225 residue reduces the MhCAT2 activity. Furthermore, the substitution of His225 with Tyr weakens the activity of MhCAT2. The oxidation modification provides a post-translational brake mechanism for the excessive scavenging of H2O2 caused by salt stress-induced catalase (CAT) over-expression. Overall, this finding provides mechanistic insights on stress tolerance augmentation by an O2•--mediated switch that regulates H2O2 homeostasis in Malus hupehensis.

Xenorecognition and costimulation of porcine endothelium-derived extracellular vesicles in initiating human porcine-specific T cell immune responses

Porcine vascular endothelial cells (PECs) form a mechanistic centerpiece of xenograft rejection. Here, we determined that resting PECs release swine leukocyte antigen class I (SLA-I) but not swine leukocyte antigen class-II DR (SLA-DR) expressing extracellular vesicles (EVs) and investigated whether these EVs proficiently initiate xenoreactive T cell responses via direct xenorecognition and costimulation. Human T cells acquired SLA-I+ EVs with or without direct contact to PECs, and these EVs colocalized with T cell receptors. Although interferon gamma-activated PECs released SLA-DR+ EVs, the binding of SLA-DR+ EVs to T cells was sparse. Human T cells demonstrated low levels of proliferation without direct contact to PECs, but marked T cell proliferation was induced following exposure to EVs. EV-induced proliferation proceeded independent of monocytes/macrophages, suggesting that EVs delivered both a T cell receptor signal and costimulation. Costimulation blockade targeting B7, CD40L, or CD11a significantly reduced T cell proliferation to PEC-derived EVs. These findings indicate that endothelial-derived EVs can directly initiate T cell-mediated immune responses, and suggest that inhibiting the release of SLA-I EVs from organ xenografts has the potential to modify the xenograft rejection. We propose a secondary-direct pathway for T cell activation via xenoantigen recognition/costimulation by endothelial-derived EVs.

Expression of CD70 Modulates NO and Redox Status in Endothelial Cells

BACKGROUND

Endothelial dysfunction is a critical component in the pathogenesis of cardiovascular diseases and is closely associated with NO levels and oxidative stress. Here, we report on novel findings linking endothelial expression of CD70 with alterations in NO and reactive oxygen species.

METHODS

CD70 expression was genetically manipulated in human aortic and pulmonary artery endothelial cells. Intracellular NO and hydrogen peroxide (H₂O₂) were measured using genetically encoded biosensors, and cellular phenotypes were assessed.

RESULTS

An unbiased phenome-wide association study demonstrated that polymorphisms in CD70 associate with vascular phenotypes. Endothelial cells treated with CD70-directed short-interfering RNA demonstrated impaired wound closure, decreased agonist-stimulated NO levels, and reduced eNOS (endothelial nitric oxide synthase) protein. This was accompanied by reduced NO bioactivity, increased 3-nitrotyrosine levels, and a decrease in the eNOS binding partner heat shock protein 90. Following treatment with the thioredoxin inhibitor auranofin or with agonist histamine, intracellular H₂O₂ levels increased up to 80% in the cytosol, plasmalemmal caveolae, and mitochondria. There was increased expression of NADPH oxidase 1 complex and gp91phox; expression of copper/zinc and manganese superoxide dismutases was also elevated. CD70 knockdown reduced levels of the H₂O₂ scavenger catalase; by contrast, glutathione peroxidase 1 expression and activity were increased. CD70 overexpression enhanced endothelial wound closure, increased NO levels, and attenuated the reduction in eNOS mRNA induced by TNFα.

CONCLUSIONS

Taken together, these data establish CD70 as a novel regulatory protein in endothelial NO and reactive oxygen species homeostasis, with implications for human vascular disease.

Anti-Inflammatory Effects of Gynura procumbens on RAW264.7 Cells via Regulation of the PI3K/Akt and MAPK Signaling Pathways

Gynura procumbens is a traditional herb and food extensively cultivated in China and Southeast Asian countries. In this work, the crude extract (CE) of G. procumbens was purified with macroporous resin to obtain the refined fraction, and its anti-inflammatory activity was compared with that of CE. Moreover, the detailed mechanisms of anti-inflammatory activity were also investigated for the first time. The results indicated that CE was more effective in anti-inflammatory activity and it could reduce the secretion of NO, TNF-α, and PGE2 via decreasing the iNOS, TNF-α, and COX-2 genes transcription and related proteins translation, which were associated with the inhibition of AP-1 and NF-κB nuclear translocation and downregulation of PI3K/Akt and MAPK signaling pathways. In conclusion, the extract of G. procumbens has a promising potential in inflammation-related disorders alleviation, and these findings could provide the basis for the comprehensive utilization of G. procumbens and the new functional food development.

Endothelial dysfunction caused by circulating microparticles from diabetic mice is reduced by PD98059 through ERK and ICAM-1

Endothelial dysfunction contributes to the development of diabetic complications and the production of circulating microparticles (MPs). Our previous study showed that diabetic mice-derived MPs (DM MPs) had increased levels of extracellular regulated protein kinase 1/2 (ERK1/2) and impaired endothelial-dependent relaxation in aortas when compared with control mice-derived MPs. This study was designed to investigate whether PD98059, an ERK1/2 inhibitor, affects the function of aortas and DM MPs. MPs were obtained from streptozotocin-induced DM, DM after PD98059 treatment, and ICR mice as control. The mice and MPs were then analyzed on the basis of their vascular function and enzyme expressions. Compared with the controls, platelet-derived MPs and ERK1/2 levels in the MPs were significantly elevated in the DM but showed little change in PD98059-treated DM. PD98059 mainly decreased ERK1/2 phosphorylation in the MPs. In the aortas of DM and DM MPs the endothelium-dependent vascular function was impaired, and there was a significantly greater improvement in the vascular function in the PD98059-treated DM aortas and the aortas treated with PD98059-treated DM MPs than in DM aortas and the aortas treated with DM MPs. Furthermore, DM MPs increased ERK1/2 and intracellular adhesion molecule-1 (ICAM-1) expressions in the aortas, but PD98059-treated DM MPs did not show these effects. For the first time, these results indicate that PD98059 treatment improves endothelial dysfunction in DM, and adhesion properties of DM MPs can be partly blocked by PD98059 via ERK and ICAM-1. These effects may explain some of the vascular complications in diabetes.

Transcriptome Profiles of the Liver in Two Cold-Exposed Sheep Breeds Revealed Different Mechanisms and Candidate Genes for Thermogenesis

Cold-induced thermogenesis plays an important role in the survival of lambs exposed to low air temperatures. The liver produces and mediates heat production in mammals; however, to date, little is known about the role of liver genes in cold-induced thermogenesis in lambs. In this study, the difference in the liver transcriptome between Altay and Hu ewe lambs was compared. Because of different backgrounds of the two breeds, we hypothesized that the transcriptome profiles of the liver would differ between breeds when exposed to cold. Cold-exposed Altay lambs activated 8 candidate genes (ACTA1, MYH1, MYH2, MYL1, MYL2, TNNC1, TNNC2, and TNNT3) involved in muscle shivering thermogenesis; 3 candidate genes (ATP2A1, SLN, and CKM) involved in muscle nonshivering thermogenesis related to the Ca²⁺ signal and creatine cycle; and 6 candidate genes (PFKM, ALDOC, PGAM2, ENO2, ENO3, and ENO4) involved in enhancing liver metabolism. In contrast, the liver may not act as the main tissue for thermogenesis in cold-exposed Hu lambs. We concluded that Altay lambs rely on liver-mediated shivering and nonshivering thermogenesis by muscle tissue to a greater extent than Hu lambs. Results from this study could provide a theoretical foundation for the breeding and production of cold-resistant lambs.

Bazedoxifene Plays a Protective Role against Inflammatory Injury of Endothelial Cells by Targeting CD40

The inflammatory response and oxidative stress play key roles in the formation and development of atherosclerosis. Bazedoxifene is a new IL6/GP130 inhibitor recommended by the FDA for clinical use as a selective estrogen receptor modulator. However, its role in cardiovascular diseases has been poorly studied. In our study, we explored the mechanism of bazedoxifene's protective effect against inflammatory injury of vascular endothelial cells (VECs) stimulated by TNF-α. Various methods were used to verify the effect of bazedoxifene on VECs, including a cell viability assay, a wound healing assay, immunofluorescence staining, and western blotting. Our results showed that TNF-α could induce inflammatory damage to VECs, which manifested as upregulated expression of CD40, increased production of ROS, enhanced adhesion of THP-1 cells to VECs, and impaired viability and migration of VECs, while bazedoxifene could significantly reduce the endothelial damage caused by TNF-α. In addition, we found that an siRNA targeting CD40 dramatically alleviated the VEC damage induced by TNF-α. Therefore, we explored the potential relationship between bazedoxifene and CD40. Our data suggest that bazedoxifene has a protective effect against VEC damage induced by TNF-α and that its underlying mechanism may be related to the regulation of CD40.

Development of Fortified Citrus Olive Oils: From Their Production to Their Nutraceutical Properties on the Cardiovascular System

: Recently the use of food by-products as natural sources of biologically active substances has been extensively investigated especially for the development of functional foods fortified with natural antioxidants. Due to their content of bioactive compounds, such as carotenoids, flavonoids and limonoids, citrus peels could be suitable to formulate enriched olive oils able to boost healthy nutrition. The aim of this study was: (i) to determine the compositional and sensory profiles of citrus olive oil; and (ii) to evaluate its nutraceutical properties in rats with high fat diet-induced metabolic syndrome and oxidative stress. The results obtained show the potential of using citrus peels as a source of bioactive compounds to improve the sensory profile as well as the phytochemical composition of olive oil. We demonstrated that the production system of Citrus x aurantium olive oil and Citrus limon olive oil improves its organoleptic properties without altering its beneficial effects, which, like control extra virgin olive oil, showed protective effects relating to glucose and serum lipid levels, metabolic activity of adipocytes, myocardial tissue functionality, oxidative stress markers and endothelial function at blood vessel level.

Different roles of soluble CD40 ligand in central nervous system damage

Backgroud and purpose: Soluble CD40 ligand (sCD40L) plays an important role in inflammation and autoimmune disorders. There is still a controversy regarding sCD40L in neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS). Herein the aims of this study were to evaluate the levels of sCD40L in patients with NMOSD, MS, and other noninflammatory neurological diseases; to investigate its potential relationship with laboratory parameters, glial fibrillary acidic protein (GFAP), thrombopoietin (TPO) and IL-6; and to address whether serum sCD40L levels in acute attacks of NMOSD patients were decreased after treatment with immunoglobulins, plasma exchange, or methylprednisolone.Materials and methods: We enrolled 13 patients with NMOSD, 9 patients with MS, and 9 patients with other noninflammatory neurological diseases. The levels of sCD40L, IL-6 were measured by cytokine multiplex assay. GFAP levels were measured by ELISA.Results: Both serum and cerebrospinal fluid (CSF) sCD40L levels were increased in NMOSD and MS. No differences were found in serum and CSF sCD40L levels between NMOSD and MS. The CSF sCD40L levels were positively correlated with the CSF cell counts in NMOSD, whereas serum sCD40L levels were positively correlated with the albumin index in MS. Furthermore, the levels of CSF sCD40L were positively correlated with CSF GFAP levels in NMOSD. Serum sCD40L levels were correlated with serum TPO levels in MS. No correlation was found between levels of sCD40L and IL-6 in NMOSD and MS. No statistically meaningful difference between NMOSD patients with or without immunotherapy. Conclusions: Our study suggests that sCD40L can contribute to the destruction of the blood-brain barrier in MS, whereas it may contribute to CNS inflammation in NMOSD. The serum sCD40L concentrations were not changed after treatment with immunoglobulins, plasma exchange, or methylprednisolone in acute attacks of NMOSD.

Tumour necrosis factor superfamily members in ischaemic vascular diseases

Current treatment of ischaemic vascular diseases such as coronary and peripheral artery disease includes angioplasty and bypass grafting, as well as lipid lowering therapies and control of other cardiovascular risk factors. Numerous members of the tumour necrosis factor superfamily (TNFSF) have recently shown emerging roles in both the protection and progression of such diseases. Understanding the role TNFSF members play in ischaemic vascular disease may provide insight into the development of novel therapeutics to prevent or treat diseases relating to atherosclerosis and ischaemia. This review summarizes the most recent findings relating to TNFSF members and the mechanisms that precede ischaemic vascular disease progression, particularly endothelial dysfunction, chronic inflammation, and atherosclerotic plaque development. This review also explores recent translational research on the role of TNFSF therapies in cardiovascular disease.

Cardiovascular benefits of tyrosol and its endogenous conversion into hydroxytyrosol in humans. A randomized, controlled trial

INTRODUCTION

The simple phenol hydroxytyrosol (OHTyr) has been associated with the beneficial health effects of extra virgin olive oil. Pre-clinical studies have identified Tyr hydroxylation, mediated by cytochrome P450 isoforms CYP2A6 and CYP2D6, as an additional source of OHTyr.

AIM

We aimed to (i) confirm Tyr to OHTyr bioconversion in vivo in humans, (ii) assess the cardiovascular benefits of this bioconversion, and (iii) determine their interaction with a polygenic activity score (PAS) from CYP2A6 and CYP2D6 genotypes.

METHODS

Randomized, crossover, controlled study. Individuals at cardiovascular risk (n = 33) received: white wine (WW) (females 1, males 2 standard drinks/day), WW plus Tyr capsules (WW + Tyr) (25  mg Tyr capsule, one per WW drink), and water (control) ad libitum. Participants were classified by a PAS as low versus normal activity metabolizers.

RESULTS

OHTyr recovery following WW + Tyr was higher than after other interventions (P < 0.05). Low PAS individuals had lower OHTyr/Tyr ratios compared to individuals with normal PAS. WW + Tyr improved endothelial function, increased plasma HDL-cholesterol and antithrombin IIII, and decreased plasma homocysteine, endothelin 1, and CD40L, P65/RELA, and CFH gene expression in peripheral blood mononuclear cells (p < 0.05). Combining Tyr capsule(s) with WW abolished the increase in iNOS, eNOS, VEGFA, and CHF expressions promoted by WW (p < 0.05).

CONCLUSIONS

Tyr, and its partial biotransformation into OHTyr, promoted cardiovascular health-related benefits in humans after dietary doses of Tyr. The study design allowed the health effects of individual phenols to be singled out from the dietary matrix in which they are naturally found.

CD40L controls obesity-associated vascular inflammation, oxidative stress, and endothelial dysfunction in high fat diet-treated and db/db mice

Aims

CD40 ligand (CD40L) signaling controls vascular oxidative stress and related dysfunction in angiotensin-II-induced arterial hypertension by regulating vascular immune cell recruitment and platelet activation. Here we investigated the role of CD40L in experimental hyperlipidemia.

Methods and results

Male wild type and CD40L-/- mice (C57BL/6 background) were subjected to high fat diet for sixteen weeks. Weight, cholesterol, HDL, and LDL levels, endothelial function (isometric tension recording), oxidative stress (NADPH oxidase expression, dihydroethidium fluorescence) and inflammatory parameters (inducible nitric oxide synthase, interleukin-6 expression) were assessed. CD40L expression, weight, leptin and lipids were increased, and endothelial dysfunction, oxidative stress and inflammation were more pronounced in wild type mice on a high fat diet, all of which was almost normalized by CD40L deficiency. Similar results were obtained in diabetic db/db mice with CD40/TRAF6 inhibitor (6877002) therapy. In a small human study higher serum sCD40L levels and an inflammatory phenotype were detected in the blood and Aorta ascendens of obese patients (body mass index > 35) that underwent by-pass surgery.

Conclusion

CD40L controls obesity-associated vascular inflammation, oxidative stress and endothelial dysfunction in mice and potentially humans. Thus, CD40L represents a therapeutic target in lipid metabolic disorders which is a leading cause in cardiovascular disease.

Deficiency of T cell CD40L has minor beneficial effects on obesity-induced metabolic dysfunction

OBJECTIVE

Obesity-associated metabolic dysfunction increases the risk of multiple diseases such as type 2 diabetes and cardiovascular disease. The importance of the co-stimulatory CD40-CD40L dyad in diet-induced obesity (DIO), with opposing phenotypes arising when either the receptor (aggravating) or the ligand (protective) is deleted, has been described previously. The functions of CD40 and CD40L are cell type dependent. As co-stimulation via T cell-mediated CD40L is essential for driving inflammation, we here investigate the role of T cell CD40L in DIO.

RESEARCH DESIGN AND METHODS

CD4CreCD40L^fl/fl mice on a C57BL/6 background were generated and subjected to DIO by administration of 15 weeks of high fat diet (HFD).

RESULTS

HFD-fed CD4CreCD40L^fl/fl mice had similar weight gain, adipocyte sizes, plasma cholesterol and triglyceride levels as their wild-type (WT) counterparts. Insulin and glucose tolerance were comparable, although CD4CreCD40L^fl/fl mice did have a decreased plasma insulin concentration, suggesting a minor improvement of insulin resistance. Furthermore, although the degree of hepatosteatosis was similar in both genotypes, the gene expression of fatty acid synthase 1 and ATP-citrate lyase had decreased, whereas expression of peroxisome proliferator-activated receptor-α had increased in livers of CD4CreCD40L^fl/fl mice, suggesting decreased hepatic lipid uptake in absence of T cell CD40L.Moreover, CD4CreCD40L^fl/fl mice displayed significantly lower numbers of effector memory CD4⁺ T cells and regulatory T cells in blood and lymphoid organs compared with WT. However, immune cell composition and inflammatory status of the adipose tissue was similar in CD4CreCD40L^fl/fl and WT mice.

CONCLUSIONS

T cell CD40L deficiency results in a minor improvement of insulin sensitivity and hepatic steatosis in DIO, despite the strong decrease in effector T cells and regulatory T cells in blood and lymphoid organs. Our data indicate that other CD40L-expressing cell types are more relevant in the pathogenesis of obesity-associated metabolic dysfunction.

Evaluation of serum sST2 and sCD40L values in patients with microvascular angina

OBJECTIVES

Coronary microvascular dysfunction plays a major role in the pathogenesis of microvascular angina (MVA). Along with endothelial dysfunction, microvascular atherosclerosis and inflammation seem to contribute to the development of coronary microvascular dysfunction. Serum soluble ST2 (sST2) and serum soluble CD40 ligand (sCD40L) are two biomarkers associated with inflammation and atherosclerosis. The aim of this study was to investigate the role of these biomarkers in the pathogenesis of MVA and determine their possible association with coronary microvascular dysfunction.

METHODS

A total of 152 patients were included in the study. Ninety-one patients with MVA {median age 56 years (40-79), of which 55 are women} and sixty-one controls {median age 52 (38-76), of which 29 are women} were included in the study. Serum concentration of sST2 and sCD40L were measured with a commercially available ELISA kit.

RESULTS

Serum sST2 (median 13.6 ng/ml; interquartile range (IQR), 3.5-63.8 ng/ml vs median 10.6 ng/ml; IQR, 2.9-34.2 ng/ml, p < 0.0005) and sCD40L (median 5.3 ng/ml; IQR, 0.5-20.6 ng/ml vs median 2.2 ng/ml; IQR, 0.7-10.8 ng/ml, p < 0.0005) were significantly higher in patients with MVA compared to controls. Analysis of the associations between these biomarkers and potential contributors of MVA revealed that serum sST2 showed a positive correlation with LDL-cholesterol (r = 0.19, p = 0.016) and serum sCD40L concentrations correlated positively with hs-CRP (r = 0.22, p = 0.005). In logistic regression analysis, sCD40L and hs-CRP but not sST2 were found to be significantly associated with MVA.

CONCLUSION

Higher serum concentrations of sST2 and sCD40L in MVA patients may be associated with inflammatory activation and coronary microvascular dysfunction. Larger studies are required for understanding their role in the pathogenesis of inflammatory and possibly fibrotic process in MVA patients.

The uremic toxin hippurate promotes endothelial dysfunction via the activation of Drp1-mediated mitochondrial fission

The accumulation of uremic toxins in chronic kidney disease (CKD) induces inflammation, oxidative stress and endothelial dysfunction, which is a key step in atherosclerosis. Accumulating evidence indicates increased mitochondrial fission is a contributing mechanism for impaired endothelial function. Hippurate, a uremic toxin, has been reported to be involved in cardiovascular diseases. Here, we assessed the endothelial toxicity of hippurate and the contribution of altered mitochondrial dynamics to hippurate-induced endothelial dysfunction. Treatment of human aortic endothelial cells with hippurate reduced the expression of endothelial nitric oxide synthase (eNOS) and increased the expression of intercellular cell adhesion molecule-1 (ICAM-1) and von Willebrand factor (vWF). The mechanisms of hippurate-induced endothelial dysfunction in vitro depended on the activation of Dynamin-related protein 1 (Drp1)-mediated mitochondrial fission and overproduction of mitochondrial reactive oxygen species (mitoROS). In a rat model in which CKD was induced by 5/6 nephrectomy (CKD rat), we observed increased oxidative stress, impaired endothelium-dependent vasodilation, and elevated soluble biomarkers of endothelial dysfunction (ICAM-1 and vWF). Similarly, endothelial dysfunction was identified in healthy rats treated with disease-relevant concentrations of hippurate. In aortas of CKD rats and hippurate-treated rats, we observed an increase in Drp1 protein levels and mitochondrial fission. Inhibition of Drp1 improved endothelial function in both rat models. These results indicate that hippurate, by itself, can cause endothelial dysfunction. Increased mitochondrial fission plays an active role in hippurate-induced endothelial dysfunction via an increase in mitoROS.

Platelets, inflammation and tissue regeneration

Blood platelets have long been recognised to bring about primary haemostasis with deficiencies in platelet production and function manifesting in bleeding while upregulated function favourises arterial thrombosis. Yet increasing evidence indicates that platelets fulfil a much wider role in health and disease. First, they store and release a wide range of biologically active substances including the panoply of growth factors, chemokines and cytokines released from α-granules. Membrane budding gives rise to microparticles (MPs), another active participant within the blood stream. Platelets are essential for the innate immune response and combat infection (viruses, bacteria, micro-organisms). They help maintain and modulate inflammation and are a major source of pro-inflammatory molecules (e.g. P-selectin, tissue factor, CD40L, metalloproteinases). As well as promoting coagulation, they are active in fibrinolysis; wound healing, angiogenesis and bone formation as well as in maternal tissue and foetal vascular remodelling. Activated platelets and MPs intervene in the propagation of major diseases. They are major players in atherosclerosis and related diseases, pathologies of the central nervous system (Alzheimers disease, multiple sclerosis), cancer and tumour growth. They participate in other tissue-related acquired pathologies such as skin diseases and allergy, rheumatoid arthritis, liver disease; while, paradoxically, autologous platelet-rich plasma and platelet releasate are being used as an aid to promote tissue repair and cellular growth. The above mentioned roles of platelets are now discussed.

Glucose and angiotensin II-derived endothelial extracellular vesicles regulate endothelial dysfunction via ERK1/2 activation

In various diseases, including diabetes, extracellular vesicles (EVs) have been detected in circulation and tissues. EVs are small membrane vesicles released from various cell types under varying conditions. Recently, endothelial cell-derived EVs (EEVs) were identified as a marker of endothelial dysfunction in diabetes, but the ensuing mechanisms remain poorly understood. In this study, we dissected the ensuing pathways with respect to nitric oxide (NO) production under the condition of type 2 diabetes. Human umbilical vein endothelial cells (HUVECs) were stimulated with glucose alone and with glucose in combination with angiotensin II (Ang II) for 48 h. In supernatants from glucose + Ang II-stimulated HUVECs, release of EEVs was assessed using Western blotting with an anti-CD144 antibody. EEV release was significantly increased after stimulation of HUVECs, and high glucose + Ang II-derived EEVs impaired ACh-induced vascular relaxation responses and NO production in mice aortic rings. Furthermore, high glucose + Ang II-derived EEVs induced ERK1/2 signalling and decreased endothelial NO synthase (eNOS) protein expression in mice aortas. Furthermore, in the presence of the MEK/ERK1/2 inhibitor PD98059, high glucose plus Ang II treatment stimulated EEVs in HUVECs and those EEVs prevented the impairments of ACh-induced relaxation and NO production in mice aortas. These data strongly indicate that high glucose and Ang II directly affect endothelial cells and the production of EEVs; the resultant EEVs aggravate endothelial dysfunction by regulating eNOS protein levels and ERK1/2 signalling in mice aortas.

Relationship Between Plasma Levels of Soluble CD40 Ligand and the Presence and Severity of Isolated Coronary Artery Ectasia

OBJECTIVE

We aimed to investigate whether soluble CD40 ligand (CD40L) levels are higher in patients with isolated coronary artery ectasia (CAE) compared to patients with angiographically normal coronary arteries and those with stable coronary artery disease (CAD).

MATERIALS AND METHODS

In all, 55 patients with isolated CAE without stenosis, 55 with stable CAD, and 55 control participants with angiographically normal coronary arteries were included. The CAE severity was determined according to the Markis classification. Plasma levels of soluble CD40 ligand were measured by enzyme-linked immunosorbent assay.

RESULTS

The baseline characteristics of the 3 groups were similar. Plasma levels of soluble CD40 ligand were significantly higher in patients with CAE and CAD than in controls (2.6 ± 3.1 ng/mL and 2.0 ± 3.1 ng/mL vs 1.8 ± 2.1 ng/mL, P = .004). No difference was found between the CAE and CAD groups. Soluble CD40 ligand level was significantly higher in the type 1 Markis subgroup than that in the type 3 or type 4 subgroups ( P = .01). A receiver operating characteristic curve analysis revealed that soluble CD40 ligand level >1.2 ng/mL identified patients with isolated CAE.

CONCLUSION

Significantly higher levels of soluble CD40 ligand were detected in patients with CAE than that in control participants with normal coronary arteries, suggesting that soluble CD40 ligand may be involved in the pathogenesis of CAE. The CD40-CD40 ligand system likely plays a role in the pathogenesis of CAE.

Stratification of ST-elevation myocardial infarction patients based on soluble CD40L longitudinal changes

Involvement of soluble CD40 ligand (sCD40L) in thrombosis and inflammation on the context of coronary artery disease is currently being revised. In that perspective, we had studied the association of sCD40L with markers of platelet activation and markers of endothelial and vascular function. On that cohort, a stratification of patients with acute myocardial infarction (AMI) 1 month after percutaneous coronary intervention (PCI) was observed based on concentrations of sCD40L. The study intended to identify the groups of AMI patients with different profiles of sCD40L concentrations and verify how medication, clinical evolution, biochemical data, and markers of regulation of endothelial function at genetic (endothelial nitric oxide synthase polymorphisms) and post-transcriptional levels (circulating microRNAs) affect sCD40L serum levels. Lower quartiles of sCD40L (<2.3 ng/mL) were associated with higher concentrations of N-terminal pro-brain natriuretic peptide (NT-proBNP), high frequency of G894T polymorphism, and altered expression of a set of microRNAs assumed to be involved in the regulation of endothelial and cardiac function and myocardium hypertrophy, relative to patients in sCD40L upper quartiles. A characteristic sCD40L variation pattern in STEMI patients was identified. Low levels of sCD40L 1 month after PCI distinguish STEMI patients with worse prognosis, a compromised cardiac healing, and a persistent endothelial dysfunction, as given by the association between sCD40L, NT-proBNP, G894T polymorphism, and specific profile of miRNA expression. These results suggest sCD40L could have a prognostic value in STEMI patients.

Soluble CD40 ligand in haemodialysis patients: survival impact and cardiovascular prognostic role

CONTEXT

Soluble CD40 ligand (sCD40l) can predict cardiovascular events (CVE) and mortality in haemodialysis (HD) patients (short-, medium-term follow-up studies).

OBJECTIVE

To evaluate the relationship between sCD40l and survival, CVE and mortality in HD patients on long-term follow-up.

METHODS

We registered 46 HD patients' baseline characteristics, mortality and CVE for 108 months.

RESULTS

SCD40l correlated positively with C-reactive protein, was higher in survivors, but had no impact on survival and was not predictive for CVE or CV mortality.

CONCLUSION

The levels of sCD40l have no influence on survival or CVE and mortality in HD patients in a long-term follow-up.

Regulation of brain endothelial barrier function by microRNAs in health and neuroinflammation

Brain endothelial cells constitute the major cellular element of the highly specialized blood-brain barrier (BBB) and thereby contribute to CNS homeostasis by restricting entry of circulating leukocytes and blood-borne molecules into the CNS. Therefore, compromised function of brain endothelial cells has serious consequences for BBB integrity. This has been associated with early events in the pathogenesis of several disorders that affect the CNS, such as multiple sclerosis, HIV-associated neurologic disorder, and stroke. Recent studies demonstrate that brain endothelial microRNAs play critical roles in the regulation of BBB function under normal and neuroinflammatory conditions. This review will focus on emerging evidence that indicates that brain endothelial microRNAs regulate barrier function and orchestrate various phases of the neuroinflammatory response, including endothelial activation in response to cytokines as well as restoration of inflamed endothelium into a quiescent state. In particular, we discuss novel microRNA regulatory mechanisms and their contribution to cellular interactions at the neurovascular unit that influence the overall function of the BBB in health and during neuroinflammation.-Lopez-Ramirez, M. A., Reijerkerk, A., de Vries, H. E., Romero, I. A. Regulation of brain endothelial barrier function by microRNAs in health and neuroinflammation.

Changes of soluble CD40 ligand in the progression of acute myocardial infarction associate to endothelial nitric oxide synthase polymorphisms and vascular endothelial growth factor but not to platelet CD62P expression

Reported in vitro data implicated soluble CD40 ligand (sCD40L) in endothelial dysfunction and angiogenesis. However, whether sCD40L could exert that influence in endothelial dysfunction and angiogenesis after injury in acute myocardial infarction (AMI) patients remains unclear. In the present study, we evaluated the association of sCD40L with markers of platelet activation, endothelial, and vascular function during a recovery period early after AMI. To achieve this goal, the time changes of soluble, platelet-bound, and microparticle-bound CD40L levels over 1 month were assessed in AMI patients and correlated with endothelial nitric oxide synthase (eNOS) polymorphisms, vascular endothelial growth factor (VEGF) concentrations, and platelet expression of P-selectin (CD62P). The association of soluble form, platelet-bound, and microparticle-bound CD40L with CD62P expression on platelets, a marker of platelet activation, was also assessed to evaluate the role of CD40L in the thrombosis, whereas the association with eNOS and VEGF was to evaluate the role of CD40L in vascular dysfunction. This work shows for the first time that time changes of sCD40L over 1 month after myocardial infarct onset were associated with G894T eNOS polymorphism and with the VEGF concentrations, but not to the platelet CD62P expression. These results indicate that, in terms of AMI pathophysiology, the sCD40L cannot be consider just as being involved in thrombosis and inflammation but also as having a relevant role in vascular and endothelial dysfunction.

Blockade of CD40 ligand for intercellular communication reduces hypertension, placental oxidative stress, and AT1-AA in response to adoptive transfer of CD4+ T lymphocytes from RUPP rats

Preeclampsia (PE) is associated with altered immune activation during pregnancy. We have previously shown that adoptive transfer of CD4(+) T cells from the reduced uterine perfusion pressure (RUPP) rat model of PE increases blood pressure, oxidative stress (ROS), and inflammation in normal pregnant recipient rats. The objective of this study was to determine if blockade of communication via the CD40-CD40 ligand (CD40L) interaction between placental ischemia-induced CD4(+) T cells with endogenous normal pregnant (NP) cells would improve pathophysiology that was previously observed in NP recipient rats of RUPP CD4(+) T cells. Splenic CD4(+) T lymphocytes were magnetically separated, incubated with 2.5 μg/ml anti-CD40 ligand (αCD40L) overnight, and transferred into NP rats on day 12 of gestation (NP+RUPP CD4(+) T+anti-CD40L). On day 19 of gestation, blood pressure (MAP), blood, and tissues were collected. MAP was 99 ± 2 in NP (n = 13), 116 ± 4 in NP+RUPP CD4(+) T cells (n = 7; P < 0.01); MAP only increased to 104 ± 2 in NP+RUPP CD4(+) T cells+CD40L (n = 24) (P < 0.05 vs. NP+RUPP CD4(+) T cells). Mechanisms of hypertension in response to RUPP CD4(+) T cells include endothelin-1 (ET-1), ROS, and angiotensin II type I receptor (AT1-AA) were analyzed. Inhibition of CD40L binding reduced placental ET-1 to 2.3-fold above NP rats and normalized placental ROS from 318.6 ± 89 in NP+RUPP CD4(+) T cells (P < 0.05) to 118.7 ± 24 in NP+RUPP CD4(+) T+anti-CD40L (P < 0.05). AT1-AA was also normalized with inhibition of CD40L. These data suggest that placental ischemia-induced T-cell communication via the CD40L is one important mechanism leading to much of the pathophysiology of PE.

microRNAs for peripheral blood fraction identification: Origin, pathways and forensic relevance

microRNAs (miRNAs) are small non-coding RNAs, with a length of 18 to 24 nucleotides that play a regulatory role in several cellular processes. Since their discovery, they have been identified in cells, tissues, organs, and body fluids and their potential as molecular biomarkers for the diagnosis of various pathologic conditions has been explored. However, little is known about the origin of the extracellular miRNAs and what factors influence the levels of circulating miRNAs. This information could help the refinement of miRNAs as more effective biomarkers. Additionally, the identification of the origin of miRNAs may prove to be very useful in the association of particular miRNAs with specific pathologies. This review aims to gather information concerning the origin of miRNAs in plasma and serum, as well as to assess their potential to be use as biomarkers for these peripheral blood fractions.

Immune-mediated and lipid-mediated platelet function in atherosclerosis

PURPOSE OF REVIEW

Cardiovascular disease (CVD) is the leading cause of death and morbidity worldwide. Detailed knowledge of the mechanisms of atherosclerosis, the main underlying disease of CVD, will enable improved preventive and therapeutic options, thus potentially limiting the burden of vascular disease in aging societies. A large body of evidence illustrates the contribution of platelets to processes beyond their traditionally recognized role as mediators in thrombosis and hemostasis. Recent advances in molecular biology help to understand the complexity of atherosclerosis.

RECENT FINDINGS

This article outlines the role of platelets as modulators of immune responses in the context of atherosclerosis. It provides a short overview of interactions between platelets and endothelial cells or immune cells via direct cell contact or soluble factors during atherogenesis. By means of some well examined, exemplary pathways (e.g. CD40/CD40L dyad), this article will discuss recent discoveries in immune-related function of platelets. We also focus on the relationship between platelets and the lipid metabolism highlighting potential consequences to atherosclerosis and dyslipidemia.

SUMMARY

A better understanding of the molecular mechanisms of platelet-related immune activity allows their utilization as powerful diagnostic tools or targets of therapeutic intervention. Those findings might help to develop new classes of drugs which may supplement or replace classical anticoagulants and help clinicians to tackle CVD more efficiently.

Random Effects Model for Multiple Pathway Analysis with Applications to Type II Diabetes Microarray Data

Close to three percent of the world's population suffer from diabetes. Despite the range of treatment options available for diabetes patients, not all patients benefit from them. Investigating how different pathways correlate with phenotype of interest may help unravel novel drug targets and discover a possible cure. Many pathway-based methods have been developed to incorporate biological knowledge into the study of microarray data. Most of these methods can only analyze individual pathways but cannot deal with two or more pathways in a model based framework. This represents a serious limitation because, like genes, individual pathways do not work in isolation, and joint modeling may enable researchers to uncover patterns not seen in individual pathway-based analysis. In this paper, we propose a random effects model to analyze two or more pathways. We also derive score test statistics for significance of pathway effects. We apply our method to a microarray study of Type II diabetes. Our method may eludicate how pathways crosstalk with each other and facilitate the investigation of pathway crosstalks. Further hypothesis on the biological mechanisms underlying the disease and traits of interest may be generated and tested based on this method.

The signaling role of CD40 ligand in platelet biology and in platelet component transfusion

The CD40 ligand (CD40L) is a transmembrane molecule of crucial interest in cell signaling in innate and adaptive immunity. It is expressed by a variety of cells, but mainly by activated T-lymphocytes and platelets. CD40L may be cleaved into a soluble form (sCD40L) that has a cytokine-like activity. Both forms bind to several receptors, including CD40. This interaction is necessary for the antigen specific immune response. Furthermore, CD40L and sCD40L are involved in inflammation and a panoply of immune related and vascular pathologies. Soluble CD40L is primarily produced by platelets after activation, degranulation and cleavage, which may present a problem for transfusion. Soluble CD40L is involved in adverse transfusion events including transfusion related acute lung injury (TRALI). Although platelet storage designed for transfusion occurs in sterile conditions, platelets are activated and release sCD40L without known agonists. Recently, proteomic studies identified signaling pathways activated in platelet concentrates. Soluble CD40L is a good candidate for platelet activation in an auto-amplification loop. In this review, we describe the immunomodulatory role of CD40L in physiological and pathological conditions. We will focus on the main signaling pathways activated by CD40L after binding to its different receptors.

Role of interferon alpha in endothelial dysfunction: insights into endothelial nitric oxide synthase-related mechanisms

Systemic lupus erythematosus (SLE) is an autoimmune disease that is characterized by the production of autoantibodies against nuclear antigens such as double-stranded DNA. Lupus predominantly affects women (ratio, 9:1). Moreover, premenopausal women with SLE are 50 times more likely to have a myocardial infarction. Although specific risk factors for advanced cardiovascular complications have not been identified in this patient population, endothelial dysfunction is highly prevalent. Recent studies show that the type I interferon signature gene expression coincides with impaired brachial artery flow-mediated dilation and diminished endothelial progenitor cell circulation, both markers of impaired endothelial function. Although many factors promote the development of vascular endothelial dysfunction, all pathways converge on the diminished activity of endothelial nitric oxide synthase (eNOS) and loss of nitric oxide (NO) bioavailability. Studies examining the effects of type I interferons on eNOS and NO in SLE are missing. This literature review examines the current literature regarding the role of type I interferons in cardiovascular disease and its known effects on regulators of eNOS and NO bioavailability that are important for proper endothelial cell function.

Pathophysiological roles and clinical importance of biomarkers in acute coronary syndrome

Early diagnosis of acute coronary syndrome (ACS) is important to guide appropriate therapy at a time when it is most likely to be of value. Accurate prognostic and risk stratification will facilitate high-risk patients to have early advanced diagnostic investigations and early appropriate interventions in a cost-effective and efficient manner, while those patients at low risk of ACS complications do not need such costly diagnostic tests and unnecessary hospital admission. Recent investigations have demonstrated that elevation of biomarkers upstream from acute-phase biomarkers, biomarkers of plaque destabilization and rupture, biomarkers of myocardial ischemia, necrosis, and dysfunction may provide an earlier assessment of patient risk and identify patients with higher risk of having an adverse event. This review provides an overview of the pathophysiology and clinical characteristics of several well-established biomarkers as well as emerging biomarkers that may have potential clinical utility in patients with ACS. Such emerging biomarkers hold promise and need to be more thoroughly evaluated before utilization in routine clinical practice.

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.

TWEAK enhances E-selectin and ICAM-1 expression, and may contribute to the development of cutaneous vasculitis

Our previous work indicated that TWEAK is associated with various types of cutaneous vasculitis (CV). Herein, we investigate the effects of TWEAK on vascular injury and adhesion molecule expression in CV mice. We showed that TWEAK priming in mice induced a local CV. Furthermore, TWEAK priming also increased the extravasation of FITC-BSA, myeloperoxidase activity and the expression of E-selectin and ICAM-1. Conversely, TWEAK blockade ameliorated the LPS-induced vascular damage, leukocyte infiltrates and adhesion molecules expression in LPS-induced CV. In addition, TWEAK treatment of HDMECs up-regulated E-selectin and ICAM-1 expression at both mRNA and protein levels. TWEAK also enhanced the adhesion of PMNs to HDMECs. Finally, western blot data revealed that TWEAK can induce phosphorylation of p38, JNK and ERK in HDMECs. These data suggest that TWEAK acted as an inducer of E-selectin and ICAM-1 expression in CV mice and HDMECs, may contribute to the development of CV.

Excess soluble CD40L contributes to blood brain barrier permeability in vivo: implications for HIV-associated neurocognitive disorders

Despite the use of anti-retroviral therapies, a majority of HIV-infected individuals still develop HIV-Associated Neurocognitive Disorders (HAND), indicating that host inflammatory mediators, in addition to viral proteins, may be contributing to these disorders. Consistently, we have previously shown that levels of the inflammatory mediator soluble CD40L (sCD40L) are elevated in the circulation of HIV-infected, cognitively impaired individuals as compared to their infected, non-impaired counterparts. Recent studies from our group suggest a role for the CD40/CD40L dyad in blood brain barrier (BBB) permeability and interestingly, sCD40L is thought to regulate BBB permeability in other inflammatory disorders of the CNS. Using complementary multiphoton microscopy and quantitative analyses in wild-type and CD40L deficient mice, we now reveal that the HIV transactivator of transcription (Tat) can induce BBB permeability in a CD40L-dependent manner. This permeability of the BBB was found to be the result of aberrant platelet activation induced by Tat, since depletion of platelets prior to treatment reversed Tat-induced BBB permeability. Furthermore, Tat treatment led to an increase in granulocyte antigen 1 (Gr1) positive monocytes, indicating an expansion of the inflammatory subset of cells in these mice, which were found to adhere more readily to the brain microvasculature in Tat treated animals. Exploring the mechanisms by which the BBB becomes compromised during HIV infection has the potential to reveal novel therapeutic targets, thereby aiding in the development of adjunct therapies for the management of HAND, which are currently lacking.

Essential role of microRNA-155 in regulating endothelium-dependent vasorelaxation by targeting endothelial nitric oxide synthase

Nitric oxide generated by endothelial nitric oxide synthase (eNOS) plays an important role in maintaining cardiovascular homeostasis. Under various pathological conditions, abnormal expression of eNOS contributes to endothelial dysfunction and the development of cardiovascular diseases. A variety of pathological stimuli has been reported to decrease eNOS expression mainly through decreasing eNOS mRNA stability by regulating the binding of several cytosolic proteins to the cis-acting sequences within eNOS mRNA 3' untranslated regions. However, the detailed mechanisms remain elusive. Because microRNAs inhibit gene expression through binding to the 3' untranslated regions of their target mRNAs, microRNAs may be the important posttranscriptional modulators of eNOS expression. Here, we provided evidence that eNOS is a direct target of miR-155. Overexpression of miR-155 decreased, whereas inhibition of miR-155 increased, eNOS expression and NO production in human umbilical vein endothelial cells and acetylcholine-induced endothelium-dependent vasorelaxation in human internal mammary arteries. Inflammatory cytokines including tumor necrosis factor-α increased miR-155 expression. Inhibition of miR-155 reversed tumor necrosis factor-α-induced downregulation of eNOS expression and impairment of endothelium-dependent vasorelaxation. Moreover, we observed that simvastatin attenuated tumor necrosis factor-α-induced upregulation of miR-155 and ameliorated the effects of tumor necrosis factor-α on eNOS expression and endothelium-dependent vasodilation. Simvastatin decreased miR-155 expression through interfering mevalonate-geranylgeranyl-pyrophosphate-RhoA signaling pathway. These findings indicated that miR-155 is an essential regulator of eNOS expression and endothelium-dependent vasorelaxation. Inhibition of miR-155 may be a new therapeutic approach to improve endothelial dysfunction during the development of cardiovascular diseases.

Preeclampsia serum upregulates CD40/CD40L expression and induces apoptosis in human umbilical cord endothelial cells

BACKGROUND

The endothelial cell dysfunction observed in preeclampsia (PE) may be induced by CD40/CD40L signaling. This study investigated the role of CD40/CD40L in the pathogenesis of PE by comparing the effect of maternal serum obtained from healthy pregnant women and PE patients on HUVEC cell growth, apoptosis and CD40/CD40L expression.

METHODS

Maternal serum was obtained from 20 patients with PE (PE group) as well as 20 healthy pregnant women (control group). The human umbilical endothelial cell line, CRL1730, was cultured in the presence of maternal serum for 24, 48, and 72 h after which cell growth and apoptosis were assessed by MTT and flow cytometry analysis, respectively. CD40/CD40L expression was determined using flow cytometry and RT-PCR analyses.

RESULTS

As compared to CRL1730 cells treated with control sera, those treated with PE sera had altered morphology, decreased cell growth, increased apoptosis and greater CD40/CD40L protein and mRNA expression. Stimulation of CD40/CD40L protein and mRNA expression by PE sera was greatest at 24 h.

CONCLUSIONS

PE sera may induce endothelial cell damage possibly through increased CD40/CD40L expression in early-onset PE. Further studies are necessary to determine the factor(s) in PE sera responsible for the observed changes in endothelial cell viability.

MicroRNAs in Postischemic Vascular Repair

The term angiogenesis describes the growth of endothelial sprouts from preexisting postcapillary venules. More recently, this term has been used to generally indicate the growth and remodeling process of the primitive vascular network into a complex network during development. In adulthood, angiogenesis is activated as a reparative process during wound healing and following ischemia, and it plays a key role in tumor growth and metastasis as well as in inflammatory diseases and diabetic retinopathy. MicroRNAs (miRNAs) are endogenous, small, noncoding RNAs that negatively control gene expression of target mRNAs. In this paper, we aim at describing the role of miRNAs in postischemic angiogenesis. First, we will describe the regulation and the expression of miRNAs in endothelial cells. Then, we will analyze the role of miRNAs in postischemic vascular repair. Finally, we will discuss the role of circulating miRNAs as potential biomarkers in ischemic diseases.

Lysophosphatidic acid causes endothelial dysfunction in porcine coronary arteries and human coronary artery endothelial cells

AIM

The objective of this study was to determine the effects of lysophosphatidic acid (LPA) on endothelial functions and molecular alternations in both porcine coronary arteries and human coronary artery endothelial cells (HCAECs).

METHODS AND RESULTS

The vessel rings and HCAECs were treated with clinically relevant concentrations of LPA for different times. Vasomotor reactivity was studied with a myograph tension system. LPA (10 and 50 μM) treatment for the vessel rings significantly reduced endothelium-dependent vasorelaxation in response to bradykinin (×10(-5)M) by 32% and 49%, respectively, compared with the control (P<0.05). LPA decreased endothelial nitric oxide synthase (eNOS) mRNA and immunoreactivity levels in the vessel rings. In HCAECs, LPA reduced eNOS mRNA, phospho-eNOS and total eNOS protein levels. In addition, superoxide anion levels in LPA-treated vessel rings and HCAECs were significantly increased by lucegenin-enhanced chemiluminescence assay and dihydroethidium staining, respectively. Mitochondrial membrane potential and ATP content in LPA-treated HCAECs were substantially decreased. The mRNA levels of reactive oxygen species generating enzymes NOX4 and p40(phox) were increased, while endogenous antioxidant enzyme superoxide dismutase 1 was decreased in response to LPA treatment in HCAECs. Furthermore, exogenous antioxidant molecule selenomethionine (SeMet) effectively reversed these LPA-induced effects in both porcine coronary arteries and HCAECs.

CONCLUSIONS

LPA causes endothelial dysfunction by a mechanism associated with decreased eNOS expression and increased oxidative stress in porcine coronary arteries and HCAECs.

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.

AVE3085, an enhancer of endothelial nitric oxide synthase, restores endothelial function and reduces blood pressure in spontaneously hypertensive rats

BACKGROUND AND PURPOSE

Nitric oxide (NO) plays an important role in endothelial function, and impaired NO production is involved in hypertension. Therefore, compounds that regulate endothelial NO synthase (eNOS) may be of therapeutic benefit. A novel, low molecular weight compound AVE3085 is a recently developed compound with the ability to enhance eNOS transcription. The present study investigated the effects of AVE3085 in endothelial dysfunction associated with hypertension.

EXPERIMENTAL APPROACH

Spontaneously hypertensive rats (SHRs) were treated with AVE 3085 (10 mg·kg·day(-1) , orally) for 4 weeks. Isometric force measurement was performed on rings of isolated aortae in organ baths. Protein expression of eNOS, phosphorylated-eNOS and nitrotyrosine in the aortae were examined by Western blotting. mRNA for eNOS in rat aortae were examined by reverse-transcriptase polymerase chain reaction (RT-PCR).

KEY RESULTS

AVE3085 greatly improved endothelium-dependent relaxations in the aortae of SHRs. This functional change was accompanied by up-regulated expression of eNOS protein and mRNA, enhanced eNOS phosphorylation and decreased formation of nitrotyrosine. Furthermore, AVE3085 treatment reduced the blood pressure in SHR without affecting that of hypertensive eNOS(-/-) mice.

CONCLUSIONS AND IMPLICATIONS

The eNOS-transcription enhancer AVE3085 restored impaired endothelial function in a hypertensive model. The present study provides a solid basis for the potential development of eNOS-targeting drugs to restore down-regulated eNOS, as a new strategy in hypertension.

CD154: an immunoinflammatory mediator in systemic lupus erythematosus and rheumatoid arthritis

Systemic lupus erythematosus and rheumatoid arthritis are two major chronic inflammatory autoimmune diseases with significant prevalence rates among the population. Although the etiology of these diseases remains unresolved, several evidences support the key role of CD154/CD40 interactions in initiating and/or propagating these diseases. The discovery of new receptors (αIIbβ3, α5β1, and αMβ2) for CD154 has expanded our understanding about the precise role of this critical immune mediator in the physiopathology of chronic inflammatory autoimmune diseases in general, and in systemic lupus erythematosus and rheumatoid arthritis in particular. This paper presents an overview of the interaction of CD154 with its various receptors and outlines its role in the pathogenesis of systemic lupus erythematosus and rheumatoid arthritis. Moreover, the potential usefulness of various CD154-interfering agents in the treatment and prevention of these diseases is also discussed.

Platelets in atherosclerosis

Beyond obvious functions in haemostasis and thrombosis, platelets are considered to be essential in proinflammatory surroundings such as atherosclerosis, allergy, rheumatoid arthritis and even cancer. In atherosclerosis, platelets facilitate the recruitment of inflammatory cells towards the lesion sites and release a plethora of inflammatory mediators, thereby enriching and boosting the inflammatory milieu. Platelets do so by interacting with endothelial cells, circulating leukocytes (monocytes, neutrophils, dendritic cells, T-cells) and progenitor cells. This cross-talk enforces leukocyte activation, adhesion and transmigration. Furthermore, platelets are known to function in innate host defense through the release of antimicrobial peptides and the expression of pattern recognition receptors. In severe sepsis, platelets are able to trigger the formation of neutrophil extracellular traps (NETs), which bind and clear pathogens. The present antiplatelet therapies that target key pathways of platelet activation and aggregation therefore hold the potential to modulate platelet-derived immune functions by reducing cellular interactions of platelets with other immune components and by reducing the secretion of inflammatory proteins into the milieu. The objective of this review is to update and discuss the current perceptions of the platelet immune constituents and their prospect as therapeutic targets in an atherosclerotic setting.

Serum cytokine profiles in healthy young and elderly population assessed using multiplexed bead-based immunoassays

Background

Lipid metabolites and cytokines, including chemokines and growth factors, are the key regulators of immune cell function and differentiation, and thus, dysregulation of these regulators is associated with various human diseases. However, previous studies demonstrating a positive correlation of cytokine levels with aging may have been influenced by various environmental factors and underlying diseases. Also, data regarding cytokine profiling in the elderly are limited to a small subset of cytokines.

Methods

We compared the profiles of 22 cytokines, including chemokines and growth factors, in a case-controlled study group of a gender-matched, healthy cohort of 55 patients over the age of 65 and 55 patients under the age of 45. Assessment of serum cytokine concentrations was performed using commercially-available multiplex bead-based sandwich immunoassays.

Results

Soluble CD40 ligand (sCD40L) and transforming growth factor alpha (TGF-α) levels were significantly higher in the elderly patients, whereas granulocyte colony-stimulating factor (G-CSF), granulocyte-monocyte colony-stimulating factor (GM-CSF), and monocyte chemoattractant protein-1 (MCP-1) levels were significantly lower in the elderly patients. The partial correlation analysis demonstrating the correlation between cytokine levels when controlled for gender, systolic blood pressure, total cholesterol, HDL cholesterol, triglyceride, and serum creatinine levels further demonstrated that G-CSF, GM-CSF, and MCP-1 had significant negative correlations with age, whereas sCD40L and TGF-α had significant positive correlations.

Conclusions

Future studies will focus on examining the significance of these age-related changes in circulating cytokines and other biological markers and their potential contribution to the development of different age-associated diseases.

CCAAT/enhancer binding protein β expression is increased in the brain during HIV-1-infection and contributes to regulation of astrocyte tissue inhibitor of metalloproteinase-1

Human immunodeficiency virus (HIV)-1-associated neurocognitive disorders (HAND) associated with infection and activation of mononuclear phagocytes (MP) in the brain, occur late in disease. Infected/activated MP initiate neuroinflammation activating glial cells and ultimately disrupting neuronal function. Astrocytes secrete tissue inhibitor of metalloproteinase (TIMP)-1 in response to neural injury. Altered TIMP-1 levels are implicated in several CNS diseases. CCAAT enhancer-binding protein β (C/EBPβ), a transcription factor, is expressed in rodent brains in response to neuroinflammation, implicating it in Alzheimer's, Parkinson's, and HAND. Here, we report that C/EBPβ mRNA levels are elevated and its isoforms differentially expressed in total brain tissue lysates of HIV-1-infected and HIV-1 encephalitis patients. In vitro, HAND-relevant stimuli additively induce C/EBPβ nuclear expression in human astrocytes through 7 days of treatment. Over-expression of C/EBPβ increases TIMP-1 promoter activity, mRNA, and protein levels in human astrocytes activated with interleukin-1β. Knockdown of C/EBPβ with siRNA decreases TIMP-1 mRNA and protein levels. These data suggest that C/EBPβ isoforms are involved in complex regulation of astrocyte TIMP-1 production during HIV-1 infection; however, further studies are required to completely understand their role during disease progression.

CD40 ligand: a neo-inflammatory molecule in vascular diseases

CD40 Ligand (CD40L), a member of the TNF family, was initially thought to be solely implicated in thymus-dependent humoral responses. However, work by several groups showed that CD40L plays a more global role in various systems. Recent evidence has outlined an important role for CD40L in the physiopathology of the vascular system. Indeed, by interacting with its principal receptor, CD40, or with the recently identified receptors, namely αIIbβ3, α5β1, and Mac-1 integrins, CD40L displayed many biological functions in different types of vascular cells. In addition, the CD40L system was demonstrated a major player in the pathology of vascular diseases, such as atherosclerosis and restenosis. This review outlines the expression pattern and the functional properties of CD40L and its receptors at different cellular levels in the vascular system. In addition, we thoroughly describe evidence showing the implication of CD40L interactions in atherosclerosis, restenosis, and their associated clinical complications.

Platelet transfusions: impact on hemostasis, thrombosis, inflammation and clinical outcomes

Platelet transfusion is one of the most crucial therapeutic approaches in Medicine. However, severe and fatal adverse reactions may develop. In addition to their important function in hemostasis, platelets' role in inflammation has become more evident. Recently, platelets are also recognized as the main source of circulating soluble CD40 ligand (sCD40L, (CD154)), which plays significant roles in hemostasis, platelet activation, clot stability, interactions with other cells, and upregulation of different mediators. In this review, we will briefly highlight the importance of platelet transfusion, its role in inflammatory and thrombotic transfusion reactions, and visit the most recent findings on sCD40L.

The effect of hormone therapy and tibolone on serum CD40L and ADAM-8 in healthy post-menopausal women

BACKGROUND/AIM

The role of neutrophils and platelets in atherothrombotic disease is well established. The aim of our study was to investigate the effect of HT and tibolone on the soluble markers of neutrophil and platelet activation, "a disentigrin and metalloproteinase domain" (ADAM-8) and CD40 ligand (CD40L) respectively, in healthy post-menopausal women.

SUBJECTS AND METHODS

One hundred and six healthy post-menopausal women were randomly allocated to: estradiol plus drospirenone (E₂/DSP), E₂ hemihydrate 1 mg plus norethisterone acetate (E₂/NETA) 0.5 mg, and tibolone 2.5 mg. Serum ADAM-8 and CD40L were measured at baseline and at 6 months.

RESULTS

Baseline values of ADAM-8 and CD40L were similar between groups. No significant correlation was revealed between ADAM-8 or CD40L and parameters related to cardiovascular risk factors in each group. No significant changes were observed between baseline values and values at 6 months (E₂/DSP group: ADAM-8: 267.4±71.3 pg/ml vs 270.7±42.8 pg/ml, p=0.86, CD40L: 6.43±3.13 vs 6.79±2.70 ng/ml, p=0.67), (E₂/NETA group: ADAM-8: 308.3±64.3 vs 294.7±57.7 pg/ml, p=0.40, CD40L: 9.68±2.81 vs 8.59±5.13 ng/ml, p=0.51), (tibolone group: ADAM-8: 307.5±87.5 vs 289±48.1 pg/ml, p=0.48, CD40L: 9.46±4.30 vs 9.26±4.60 ng/ml, p=0.99).

CONCLUSIONS

Our study has not revealed an association between estrogen plus progestin treatment or tibolone on serum ADAM-8 and CD40L levels in healthy post-menopausal women. Larger prospective studies are needed to further investigate the effect of low-dose HT or tibolone on serum markers of neutrophil and platelet activation.

Target: ligand interactions of the vascular endothelium. Implications for molecular imaging in inflammation

Molecular imaging refers to the non-invasive visualisation of biological processes at the molecular and cellular levels within a living organism, and offers a wide range of potential benefits to both clinical medicine and research into novel therapeutic agents. Inflammation plays an important role in a wide variety of pathological processes and imaging the molecular and cellular machinery that underlies chronic inflammation is attractive and feasible. In this review, we present an overview of molecular imaging of inflammation. We start by characterising molecular and cellular events in early inflammation, identifying current and potential future imaging targets. We focus on the imaging of endothelial cells, which mediate the important first steps in inflammation in any tissue, are readily accessible to imaging probes and which present an approach that can be applied across multiple modalities. We then review the generic requirements for imaging contrast agents and focus on the important considerations in respect of ligands, ligand-target interactions and contrast vehicles. We aim to provide an integrated view of current progress with a focus on promising recent developments in experimental and translational molecular imaging.

Dyad of CD40/CD40 ligand fosters neuroinflammation at the blood-brain barrier and is regulated via JNK signaling: implications for HIV-1 encephalitis

Human immunodeficiency virus 1 (HIV-1) infection may result in activation of peripheral monocytes followed by their infiltration into the CNS, where the release of proinflammatory mediators causes neurologic disease. Previously, we detected high levels of soluble CD40 ligand (CD40L) in CSF and plasma of HIV-infected patients with cognitive impairment. We now show that CD40, a receptor for CD40L, is highly expressed in brain endothelial cells of patients affected by HIV-1 encephalitis (HIVE), suggesting an important role for the CD40/CD40L dyad in regulating blood-brain barrier (BBB) functions. This concept was further supported by in vitro experiments. Exposure of primary human brain microvascular endothelial cells (BMVECs) to CD40L upregulated the expression of adhesion molecules intracellular adhesion molecule-1 and vascular cell adhesion molecule-1, which caused a fourfold increase in monocyte adhesion to BMVECs and stimulated migration across an in vitro BBB model. Investigations into the intracellular signaling pathways that govern these events revealed that cJUN-N-terminal kinase (JNK) is critical to CD40 activation in the BMVECs. CD40L induced activation of mixed-lineage-kinase-3 and JNK, leading to the subsequent activation of cJUN/AP-1 (activating-protein-1). JNK inhibition in the BMVECs prevented CD40L-mediated induction of adhesion molecules, monocyte adhesion, and transendothelial migration. These new findings support the concept that the CD40/CD40L dyad plays an important role in HIVE neuroinflammation.