Binding of von Willebrand factor by coagulase-negative staphylococci

Abstract

Coagulase-negative staphylococci (CNS) are the most common infectious microorganisms isolated from prosthetic devices. To determine whether von Willebrand factor (vWF) acts as an adhesin in bacterial recognition, bacterial binding of recombinant vWF (rvWF) was studied. Eleven CNS strains, belonging to S. epidermidis, S. haemolyticus and S. hominis species, bound soluble rvWF, but to a lesser extent than S. aureus. S. epidermidis strain H2-W bound 125 I-labelled rvWF in a dose-dependent manner. The binding could be inhibited by unlabelled rvWF and thrombospondin, but not by fibrinogen, vitronectin or the carbohydrates N-acetylgalactoseamine, D-galactose, D-glucose, and D-fucose. Pre-incubation of rvWF with type I collagen and Arg-Gly-AspSer (RGDS) peptides did not inhibit binding, whereas pre-incubation of rvWF with heparin decreased binding significantly. The interaction between CNS and rvWF was sensitive to proteinase treatment of bacterial cells. CNS strains bound to immobilised rvWF an extent greater or equal to the positive control strain S. aureus Cowan I. rvWF binding structures from bacterial cell wall were detected by immunoblot. Cowan I strain had 140-, 90-and 38-kDa binding molecules. S. haemolyticus strain SM131 and S. epidermidis strain H2-W had two (120 and 60 kDa) and five (120, 90, 60, 52 and 38 kDa) binding molecules, respectively. Similar binding structures were formed when cell wall extracts from these strains were incubated with thrombospondin. These results indicate that specific ligand-receptor interaction between CNS and rvWF may contribute to bacterial adhesion and colonisation on biomaterial surfaces. Heparin-binding domains of rvWF might be the crucial regions for bacterial attachment. rvWF and thrombospondin may recognise similar molecules in staphylococcal cell wall extracts.

Ultralarge von Willebrand Factor Fibers Mediate Luminal Staphylococcus aureus Adhesion to an Intact Endothelial Cell Layer Under Shear Stress

“…Blocking of the A1 domain with heparin revealed a 6-fold reduction of the VWF-mediated adhesion of S aureus to the endothelium ( Figure 6A). In agreement with our data, Li et al 38 previously showed a heparin-dependent reduction of bacterial binding to VWF. We confirmed the impact of the A1 domain by a reduced adherence of S aureus to functionalized surfaces coated with recombinant VWF lacking the A1 domain.…”

The N-terminal of thrombospondin-1 is essential for coagulase-negative staphylococcal binding

“…This ®nding is consistent with the previous observation that the binding of rvWF and TSP is mediated through similar cell surface structures in both CNS and S. aureus, and suggests that the inhibitory effect of rvWF may be the result of competition for the same surface receptor [9]. Glycoproteins including Clu, Vn, Tf and IgG did not inhibit binding of TSP by either S. epidermidis J9P or S. aureus Cowan 1, indicating that the binding molecules on the bacteria for TSP are not identical to those for these glycoproteins [4,8,24].…”

“…Bacteria were incubated with proteinase K 40 ìg, trypsin 100 ìg, chymotrypsin 100 ìg or 100 mM sodium periodate, as described previously [9,27]. Suspensions of bacterial cells were heated at 1008C for 30 min and rapidly ice-cooled.…”

“…Clinical isolates of CNS were from various infections: six from CSF shunt infections, six from endocarditis, three from osteomyelitis, six from graft infections and six from intravenous catheter-related septicaemia. Four S. aureus reference strains (Cowan 1, Wood 46, V8 and ISP 546) were analysed [9,20,26]. Bacterial cells were grown in TH broth at 378C for 20±22 h on a gyratory shaker with vigorous agitation, except when different culture conditions were compared.…”

“…S. aureus has also been shown to bind TSP [20]. There have been a few reports on the binding of TSP by CNS but the mechanism of the interaction has not been demonstrated clearly [9,20,21].…”