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

Energy gain of wetted-foam implosions with auxiliary heating for inertial fusion studies

Low convergence ratio implosions (where wetted-foam layers are used to limit capsule convergence, achieving improved robustness to instability growth) and auxiliary heating (where electron beams are used to provide collisionless heating of a hotspot) are two promising techniques that are being explored for inertial fusion energy applications. In this paper, a new analytic study is presented to understand and predict the performance of these implosions. Firstly, conventional gain models are adapted to produce gain curves for fixed convergence ratios, which are shown to well-describe previously simulated results. Secondly, auxiliary heating is demonstrated to be well understood and interpreted through the burn-up fraction of the deuterium-tritium fuel, with the gradient of burn-up with respect to burn-averaged temperature shown to provide good qualitative predictions of the effectiveness of this technique for a given implosion. Simulations of auxiliary heating for a range of implosions are presented in support of this and demonstrate that this heating can have significant benefit for high gain implosions, being most effective when the burn-averaged temperature is between 5 and 20 keV

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

Programmed cell death and its role in inflammation

Cell death plays an important role in the regulation of inflammation and may be the result of inflammation. The maintenance of tissue homeostasis necessitates both the recognition and removal of invading microbial pathogens as well as the clearance of dying cells. In the past few decades, emerging knowledge on cell death and inflammation has enriched our molecular understanding of the signaling pathways that mediate various programs of cell death and multiple types of inflammatory responses. This review provides an overview of the major types of cell death related to inflammation. Modification of cell death pathways is likely to be a logical therapeutic target for inflammatory diseases

KLF2-induced actin shear fibers control both alignment to flow and JNK signaling in vascular endothelium

The shear stress-induced transcription factor Kruppel-like factor 2 (KLF2) confers antiinflammatory properties to endothelial cells through the inhibition of activator protein 1, presumably by interfering with mitogen-activated protein kinase (MAPK) cascades. To gain insight into the regulation of these cascades by KLF2, we used antibody arrays in combination with time-course mRNA microarray analysis. No gross changes in MAPKs were detected; rather, phosphorylation of actin cytoskeleton-associated proteins, including focal adhesion kinase, was markedly repressed by KLF2. Furthermore, we demonstrate that KLF2-mediated inhibition of Jun NH2-terminal kinase (JNK) and its downstream targetsATF2/c-Jun is dependent on the cytoskeleton. Specifically, KLF2 directs the formation of typical short basal actin filaments, termed shear fibers by us, which are distinct from thrombinor tumor necrosis factor-alpha-induced stress fibers. KLF2 is shown to be essential for shear stress-induced cell alignment, concomitant shear fiber assembly, and inhibition of JNK signaling. These findings link the specific effects of shear-induced KLF2 on endothelial morphology to the suppression of JNK MAPK signaling in vascular homeostasis via novel actin shear fibers. (Blood. 2010; 115: 2533-2542

Contributions of 12/15-Lipoxygenase to Bleeding in the Brain Following Ischemic Stroke

Ischemic strokes are caused by one or more blood clots that typically obstruct one of the major arteries in the brain, but frequently also result in leakage of the blood-brain barrier and subsequent hemorrhage. While it has long been known that the enzyme 12/15-lipoxygenase (12/15-LOX) is up-regulated following ischemic strokes and contributes to neuronal cell death, recent research has shown an additional major role for 12/15-LOX in causing this hemorrhagic transformation. These findings have important implications for the use of 12/15-LOX inhibitors in the treatment of stroke

OPG content of mock- or KLF2-transduced BOECs.

<p>(A) Immunofluorescence image showing co-localization of OPG (green) and VWF (red) in both mock- and KLF2-tranduced BOECs. Nuclei were stained using DAPI (blue). Scale bars: 10 µm.(B) Western blot analysis for VWF, KLF2, IL-8 and IL-6 expression in lysates of mock- and KLF2-transduced BOECs; α-tubulin was shown as a loading control.</p

IL-6 and IL-8 content of KLF2-transduced BOECs.

<p>(A) Immunofluorescence image showing co-localization of IL-6 (green) and VWF (red) in IL-1β-treated KLF2- and mock-transduced BOECs. Nuclei were visualized with DAPI (blue). Scale bars: 10 µm. (B) Western blot analysis for VWF, KLF2, IL-8 and IL-6 expression in lysates of mock- and KLF2-transduced BOECs; α-tubulin was shown as a loading control. (C) Immunofluorescence image showing co-localization of IL-8 (green) and VWF (red) in IL-1β-treated KLF2- and mock-transduced BOECs. Nuclei were visualized with DAPI (blue). Scale bars: 10 µm. (D) Release of VWF from PMA-stimulated KLF2 (black bars)- and mock (white bars)-transduced cells (IL-1β-treated), measured by determining the concentration of VWF in the conditioned medium by ELISA. **P<0.001; ***P<0.0001 by Students t-test (E-F) Release of IL-6 and IL-8 from PMA-stimulated KLF2 (black bars)- and mock (white bars)-transduced cells (IL-1β-treated), measured by determining the concentration of IL-6 and IL-8 in the conditioned medium by ELISA. The amount of IL-6 released without stimulation was slightly reduced in KLF2 expressing cells when compared to mock-transduced cells. NS: non-significant; *P<0.01; ***P<0.0001 by Students t-test.</p

Expression of KLF2 in BOECs.

<p>(A) Immunofluorescent analysis of mock- and KLF2-transduced BOECs. Cells were immunostained for CD31 (red) and KLF2 (green); nuclei were stained using DAPI (blue). Scale bars: 20 µm; (B) Western blot analysis of KLF2 expression in lysates of KLF2-transduced and mock-transduced BOECs; α-tubulin is shown as a loading control.</p