Characterization of human platelet binding of recombinant T cell receptor ligand

<p>Abstract</p> <p>Background</p> <p>Recombinant T cell receptor ligands (RTLs) are bio-engineered molecules that may serve as novel therapeutic agents for the treatment of neuroinflammatory conditions such as multiple sclerosis (MS). RTLs contain membrane distal α1 plus β1 domains of class II major histocompatibility complex linked covalently to specific peptides that can be used to regulate T cell responses and inhibit experimental autoimmune encephalomyelitis (EAE). The mechanisms by which RTLs impede local recruitment and retention of inflammatory cells in the CNS, however, are not completely understood.</p> <p>Methods</p> <p>We have recently shown that RTLs bind strongly to B cells, macrophages, and dendritic cells, but not to T cells, in an antigenic-independent manner, raising the question whether peripheral blood cells express a distinct RTL-receptor. Our study was designed to characterize the molecular mechanisms by which RTLs bind human blood platelets, and the ability of RTL to modulate platelet function.</p> <p>Results</p> <p>Our data demonstrate that human blood platelets support binding of RTL. Immobilized RTL initiated platelet intracellular calcium mobilization and lamellipodia formation through a pathway dependent upon Src and PI3 kinases signaling. The presence of RTL in solution reduced platelet aggregation by collagen, while treatment of whole blood with RTL prolonged occlusive thrombus formation on collagen.</p> <p>Conclusions</p> <p>Platelets, well-known regulators of hemostasis and thrombosis, have been implicated in playing a major role in inflammation and immunity. This study provides the first evidence that blood platelets express a functional RTL-receptor with a putative role in modulating pathways of neuroinflammation.</p

Search for the neutral Higgs bosons of the minimal supersymmetric standard model in pp collisions at root s=7 TeV with the ATLAS detector

A search for neutral Higgs bosons of the Minimal Supersymmetric Standard Model (MSSM) is reported. The analysis is based on a sample of proton-proton collisions at a centre-of-mass energy of 7TeV recorded with the ATLAS detector at the Large Hadron Collider. The data were recorded in 2011 and correspond to an integrated luminosity of 4.7 fb-1 to 4.8 fb-1. Higgs boson decays into oppositely-charged muon or τ lepton pairs are considered for final states requiring either the presence or absence of b-jets. No statistically significant excess over the expected background is observed and exclusion limits at the 95% confidence level are derived. The exclusion limits are for the production cross-section of a generic neutral Higgs boson, φ, as a function of the Higgs boson mass and for h/A/H production in the MSSM as a function of the parameters mA and tan β in the mhmax scenario for mA in the range of 90GeV to 500 GeV. Copyright CERN

CXCR7 Expression Disrupts Endothelial Cell Homeostasis and Causes Ligand-Dependent Invasion

The homeostatic function of endothelial cells (EC ) is critical for a number of physiological processes including vascular integrity, immunity, and wound healing. Indeed, vascular abnormalities resulting from EC dysfunction contribute to the development and spread of malignancies. The alternative SDF-1/CXCL12 receptor CXCR7 is frequently and specifically highly expressed in tumor-associated vessels. In this study, we investigate whether CXCR7 contributes to vascular dysfunction by specifically examining the effect of CXCR7 expression on EC barrier function and motility. We demonstrate that CXCR7 expression in EC results in redistribution of CD31/PECAM-1 and loss of contact inhibition. Moreover, CXCR7+ EC are deficient in barrier formation. We show that CXCR7-mediated motility has no influence on angiogenesis but contributes to another motile process, the invasion of CXCR7+ EC into ligand-rich niches. These results identify CXCR7 as a novel manipulator of EC barrier function via alteration of PECAM-1 homophilic junctions. As such, aberrant expression of CXCR7 in the vasculature has the potential to disrupt vascular homeostasis and could contribute to vascular dysfunction in cancer systems

Ibrutinib Inhibits BMX-Dependent Endothelial VCAM-1 Expression In Vitro and Pro-Atherosclerotic Endothelial Activation and Platelet Adhesion In Vivo.

INTRODUCTION: Inflammatory activation of the vascular endothelium leads to overexpression of adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1), contributing to the pro-thrombotic state underpinning atherogenesis. While the role of TEC family kinases (TFKs) in mediating inflammatory cell and platelet activation is well defined, the role of TFKs in vascular endothelial activation remains unclear. We investigated the role of TFKs in endothelial cell activation in vitro and in a nonhuman primate model of diet-induced atherosclerosis in vivo. METHODS AND RESULTS: In vitro, we found that ibrutinib blocked activation of the TFK member, BMX, by vascular endothelial growth factors (VEGF)-A in human aortic endothelial cells (HAECs). Blockade of BMX activation with ibrutinib or pharmacologically distinct BMX inhibitors eliminated the ability of VEGF-A to stimulate VCAM-1 expression in HAECs. We validated that treatment with ibrutinib inhibited TFK-mediated platelet activation and aggregation in both human and primate samples as measured using flow cytometry and light transmission aggregometry. We utilized contrast-enhanced ultrasound molecular imaging to measure platelet GPIbα and endothelial VCAM-1 expression in atherosclerosis-prone carotid arteries of obese nonhuman primates. We observed that the TFK inhibitor, ibrutinib, inhibited platelet deposition and endothelial cell activation in vivo. CONCLUSION: Herein we found that VEGF-A signals through BMX to induce VCAM-1 expression in endothelial cells, and that VCAM-1 expression is sensitive to ibrutinib in vitro and in atherosclerosis-prone carotid arteries in vivo. These findings suggest that TFKs may contribute to the pathogenesis of atherosclerosis and could represent a novel therapeutic target.National Institute of Health (R01HL101972, R01HL078610, R01HL130046, R01HL151367, P51OD011092). National Institute of Health grant (P51OD011092)

A physical sciences network characterization of non-tumorigenic and metastatic cells.

To investigate the transition from non-cancerous to metastatic from a physical sciences perspective, the Physical Sciences-Oncology Centers (PS-OC) Network performed molecular and biophysical comparative studies of the non-tumorigenic MCF-10A and metastatic MDA-MB-231 breast epithelial cell lines, commonly used as models of cancer metastasis. Experiments were performed in 20 laboratories from 12 PS-OCs. Each laboratory was supplied with identical aliquots and common reagents and culture protocols. Analyses of these measurements revealed dramatic differences in their mechanics, migration, adhesion, oxygen response, and proteomic profiles. Model-based multi-omics approaches identified key differences between these cells' regulatory networks involved in morphology and survival. These results provide a multifaceted description of cellular parameters of two widely used cell lines and demonstrate the value of the PS-OC Network approach for integration of diverse experimental observations to elucidate the phenotypes associated with cancer metastasis