an-vitro-model-parallel-plate-perfusion-system-to-study-bacterial

An <em>In Vitro</em> Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

Various valved conduits and stent-mounted valves are used for right ventricular outflow tract (RVOT) valve replacement in patients with congenital heart ...

KU Leuven

Chromosomal interactions connect distant enhancers and promoters on the same chromosome, activating or repressing gene expression.  encodes the Platelet-Endothelial Aggregation Receptor 1, a contact receptor involved in platelet function and megakaryocyte and endothelial cell proliferation.  expression during megakaryocyte differentiation is controlled by DNA methylation at its first CpG island. We identified a  cell-specific methylation sensitive region in endothelial cells and megakaryocytes that showed strong chromosomal interactions with , , ,  and , using available promoter capture Hi-C datasets. These genes are involved in ribosome processing, protein synthesis, cell cycle and cell proliferation. We next studied the methylation and expression profile of these five genes in Human Umbilical Vein Endothelial Cells (HUVECs) and megakaryocyte precursors. While cell-specific  methylation corresponded to variability in expression for four out of five genes, no methylation change was observed in their promoter regions across cell types. Our data suggest that  cell-type specific methylation changes may control long distance interactions with other genes. Further studies are needed to show whether such interaction data might be relevant for the genome-wide association data that showed a role for non-coding  variants in the same region and platelet function, platelet count and cardiovascular risk.

Cell-Specific PEAR1 Methylation Studies Reveal a Locus that Coordinates Expression of Multiple Genes.

Adhesion of  to endothelial cells (ECs) is paramount in infective endocarditis. Bacterial proteins such as clumping factor A (ClfA) and fibronectin binding protein A (FnbpA) mediate adhesion to EC surface molecules and (sub)endothelial matrix proteins including fibrinogen (Fg), fibrin, fibronectin (Fn) and von Willebrand factor (vWF). We studied the influence of shear flow and plasma on the binding of ClfA and FnbpA (including its sub-domains A, A, ABC, CD) to coverslip-coated vWF, Fg/fibrin, Fn or confluent ECs, making use of , expressing these adhesins heterologously. Global adherence profiles were similar in static and flow conditions. In the absence of plasma,  binding to Fg increased with shear forces, whereas binding to fibrin did not. The degree of adhesion of  to EC-bound Fn and of  to EC-bound Fg, furthermore, was similar to that of  to coated vWF domain A1, in the presence of vWF-binding protein (vWbp). Yet, in plasma,  adherence to activated EC-vWF/vWbp dropped over 10 minutes by 80% due to vWF-hydrolysis by a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 and that of  likewise by > 70% compared to the adhesion in absence of plasma. In contrast, plasma Fg supported high  binding to resting and activated ECs. Or, in plasma  adhesion to active endothelium occurs mainly via two complementary pathways: a rapid but short-lived vWF/vWbp pathway and a stable integrin-coupled Fg-pathway. Hence, the pharmacological inhibition of ClfA-Fg interactions may constitute a valuable additive treatment in infective endocarditis.

Marc F Hoylaerts

Centre for Molecular and Vascular Biology,
Department of Cardiovascular Sciences,
Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences

KU Leuven

An In Vitro Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

Marc F Hoylaerts

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Centre for Molecular and Vascular Biology,Department of Cardiovascular Sciences,Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences

KU Leuven

An In Vitro Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

Centre for Molecular and Vascular Biology,
Department of Cardiovascular Sciences,
Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences