MicroRNAs regulate human brain endothelial cell-barrier function in inflammation: implications for multiple sclerosis.

Blood-brain barrier (BBB) dysfunction is a major hallmark of many neurological diseases, including multiple sclerosis (MS). Using a genomics approach, we defined a microRNA signature that is diminished at the BBB of MS patients. In particular, miR-125a-5p is a key regulator of brain endothelial tightness and immune cell efflux. Our findings suggest that repair of a disturbed BBB through microRNAs may represent a novel avenue for effective treatment of MS

Expression of a retinoic acid signature in circulating CD34 cells from coronary artery disease patients

<p>Abstract</p> <p>Background</p> <p>Circulating CD34+ progenitor cells have the potential to differentiate into a variety of cells, including endothelial cells. Knowledge is still scarce about the transcriptional programs used by CD34+ cells from peripheral blood, and how these are affected in coronary artery disease (CAD) patients.</p> <p>Results</p> <p>We performed a whole genome transcriptome analysis of CD34+ cells, CD4+ T cells, CD14+ monocytes, and macrophages from 12 patients with CAD and 11 matched controls. CD34+ cells, compared to other mononuclear cells from the same individuals, showed high levels of KRAB box transcription factors, known to be involved in gene silencing. This correlated with high expression levels in CD34+ cells for the progenitor markers HOXA5 and HOXA9, which are known to control expression of KRAB factor genes. The comparison of expression profiles of CD34+ cells from CAD patients and controls revealed a less naïve phenotype in patients' CD34+ cells, with increased expression of genes from the Mitogen Activated Kinase network and a lowered expression of a panel of histone genes, reaching levels comparable to that in more differentiated circulating cells. Furthermore, we observed a reduced expression of several genes involved in CXCR4-signaling and migration to SDF1/CXCL12.</p> <p>Conclusions</p> <p>The altered gene expression profile of CD34+ cells in CAD patients was related to activation/differentiation by a retinoic acid-induced differentiation program. These results suggest that circulating CD34+ cells in CAD patients are programmed by retinoic acid, leading to a reduced capacity to migrate to ischemic tissues.</p

Heme oxygenase-1 is required for angiogenic function of bone marrow-derived progenitor cells : role in therapeutic revascularization

Aims: Heme oxygenase-1 (HO-1) is a cytoprotective enzyme that can be down-regulated in diabetes. Its importance for mature endothelium has been described, but its role in proangiogenic progenitors is not well known. We investigated the effect of HO-1 on the angiogenic potential of bone marrow-derived cells (BMDCs) and on blood flow recovery in ischemic muscle of diabetic mice. Results: Lack of HO-1 decreased the number of endothelial progenitor cells (Lin−CD45−cKit-Sca-1+VEGFR-2+) in murine bone marrow, and inhibited the angiogenic potential of cultured BMDCs, affecting their survival under oxidative stress, proliferation, migration, formation of capillaries, and paracrine proangiogenic potential. Transcriptome analysis of HO-1−/− BMDCs revealed the attenuated up-regulation of proangiogenic genes in response to hypoxia. Heterozygous HO-1+/− diabetic mice subjected to hind limb ischemia exhibited reduced local expression of vascular endothelial growth factor (VEGF), placental growth factor (PlGF), stromal cell-derived factor 1 (SDF-1), VEGFR-1, VEGFR-2, and CXCR-4. This was accompanied by impaired revascularization of ischemic muscle, despite a strong mobilization of bone marrow-derived proangiogenic progenitors (Sca-1+CXCR-4+) into peripheral blood. Blood flow recovery could be rescued by local injections of conditioned media harvested from BMDCs, but not by an injection of cultured BMDCs. Innovation: This is the first report showing that HO-1 haploinsufficiency impairs tissue revascularization in diabetes and that proangiogenic in situ response, not progenitor cell mobilization, is important for blood flow recovery. Conclusions: HO-1 is necessary for a proper proangiogenic function of BMDCs. A low level of HO-1 in hyperglycemic mice decreases restoration of perfusion in ischemic muscle, which can be rescued by a local injection of conditioned media from cultured BMDCs

Neurotrophin p75 receptor (p75NTR) promotes endothelial cell apoptosis and inhibits angiogenesis:implications for diabetes-induced impaired neovascularization in ischemic limb muscles

Diabetes impairs endothelial function and reparative neovascularization. The p75 receptor of neurotrophins (p75&lt;sup&gt;NTR&lt;/sup&gt;), which is scarcely present in healthy endothelial cells (ECs), becomes strongly expressed by capillary ECs after induction of peripheral ischemia in type-1 diabetic mice. Here, we show that gene transfer-induced p75&lt;sup&gt;NTR&lt;/sup&gt; expression impairs the survival, proliferation, migration, and adhesion capacities of cultured ECs and endothelial progenitor cells (EPCs) and inhibits angiogenesis in vitro. Moreover, intramuscular p75&lt;sup&gt;NTR&lt;/sup&gt; gene delivery impairs neovascularization and blood flow recovery in a mouse model of limb ischemia. These disturbed functions are associated with suppression of signaling mechanisms implicated in EC survival and angiogenesis. In fact, p75&lt;sup&gt;NTR&lt;/sup&gt; depresses the VEGF-A/Akt/eNOS/NO pathway and additionally reduces the mRNA levels ofITGB1 [beta (1) integrin], BIRC5 (survivin), PTTG1 (securin) and VEZF1. Diabetic mice, which typically show impaired postischemic muscular neovascularization and blood perfusion recovery, have these defects corrected by intramuscular gene transfer of a dominant negative mutant form of p75&lt;sup&gt;NTR&lt;/sup&gt;. Collectively, our data newly demonstrate the antiangiogenic action of p75&lt;sup&gt;NTR&lt;/sup&gt; and open new avenues for the therapeutic use of p75&lt;sup&gt;NTR&lt;/sup&gt; inhibition to combat diabetes-induced microvascular liabilities

Effect of additional treatment with EXenatide in patients with an Acute Myocardial Infarction (EXAMI): study protocol for a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Myocardial infarction causes irreversible loss of cardiomyocytes and may lead to loss of ventricular function, morbidity and mortality. Infarct size is a major prognostic factor and reduction of infarct size has therefore been an important objective of strategies to improve outcomes. In experimental studies, glucagon-like peptide 1 and exenatide, a long acting glucagon-like peptide 1 receptor agonist, a novel drug introduced for the treatment of type 2 diabetes, reduced infarct size after myocardial infarction by activating pro-survival pathways and by increasing metabolic efficiency.</p> <p>Methods</p> <p>The EXAMI trial is a multi-center, prospective, randomized, placebo controlled trial, designed to evaluate clinical outcome of exenatide infusion on top of standard treatment, in patients with an acute myocardial infarction, successfully treated with primary percutaneous coronary intervention. A total of 108 patients will be randomized to exenatide (5 μg bolus in 30 minutes followed by continuous infusion of 20 μg/24 h for 72 h) or placebo treatment. The primary end point of the study is myocardial infarct size (measured using magnetic resonance imaging with delayed enhancement at 4 months) as a percentage of the area at risk (measured using T2 weighted images at 3-7 days).</p> <p>Discussion</p> <p>If the current study demonstrates cardioprotective effects, exenatide may constitute a novel therapeutic option to reduce infarct size and preserve cardiac function in adjunction to reperfusion therapy in patients with acute myocardial infarction.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01254123">NCT01254123</a></p

The Shear Stress-Induced Transcription Factor KLF2 Affects Dynamics and Angiopoietin-2 Content of Weibel-Palade Bodies

BACKGROUND: The shear-stress induced transcription factor KLF2 has been shown to induce an atheroprotective phenotype in endothelial cells (EC) that are exposed to prolonged laminar shear. In this study we characterized the effect of the shear stress-induced transcription factor KLF2 on regulation and composition of Weibel-Palade bodies (WPBs) using peripheral blood derived ECs. METHODOLOGY AND PRINCIPAL FINDINGS: Lentiviral expression of KLF2 resulted in a 4.5 fold increase in the number of WPBs per cell when compared to mock-transduced endothelial cells. Unexpectedly, the average length of WPBs was significantly reduced: in mock-transduced endothelial cells WPBs had an average length of 1.7 µm versus 1.3 µm in KLF2 expressing cells. Expression of KLF2 abolished the perinuclear clustering of WPBs observed following stimulation with cAMP-raising agonists such as epinephrine. Immunocytochemistry revealed that WPBs of KLF2 expressing ECs were positive for IL-6 and IL-8 (after their upregulation with IL-1β) but lacked angiopoietin-2 (Ang2), a regular component of WPBs. Stimulus-induced secretion of Ang2 in KLF2 expressing ECs was greatly reduced and IL-8 secretion was significantly lower. CONCLUSIONS AND SIGNIFICANCE: These data suggest that KLF2 expression leads to a change in size and composition of the regulated secretory compartment of endothelial cells and alters its response to physiological stimuli

Can RAP save your brain?

In this issue of Blood, Suzuki and colleagues report that the bleeding complications associated with thrombolytic therapy after ischemic stroke might be counteracted by RAP, the receptor-associated protein that inhibits ischemia-induced LRP, a signaling receptor for t-P