Shiga-toxin-induced firm adhesion of human leukocytes to endothelium is in part mediated by heparan sulfate.
BACKGROUND
Shiga toxin (Stx) is the main pathogenic factor in the haemolytic-uraemic syndrome (HUS). Stx damages the renal endothelium, which leads to inflammation and coagulation. Endothelial heparan sulfate proteoglycans (HSPG), and heparan sulfate in particular, play an important role in the inflammatory process by acting as a ligand for l-selectin. Furthermore, leukocytes are able to interact with chemokines bound to HSPG (examples are IL-8, RANTES and MCP-1). This leads to an activation of integrins on leukocytes and results in more stable leukocyte-endothelial wall adhesion. In this study, we have evaluated the effect of a subtoxic dose of Stx1 and Stx2 on the HSPG and its role in adhesion of leukocytes.


METHODS
Primary human umbilical venous endothelial cells (HUVEC) and primary human glomerular microvascular endothelial cells (GMVEC) were incubated for 24 h with a subtoxic dose of Stx1 or Stx2. Then, cells were treated with heparan sulfate-degrading enzyme heparitinase I or left untreated, followed by determination of binding leukocytes to endothelial cells in a parallel plate flow chamber.


RESULTS
In both cell types, Stx increased the amount of firmly adherent leukocytes. After removal of endothelial heparan sulfate, the number of adhering leukocytes decreased.


CONCLUSIONS
HSPG have a distinctive role in adhesion of leukocytes to endothelial cells stimulated by a subtoxic dose of Stx.
Geelen
Joyce
J
Department of Paediatric Nephrology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands. j.geelen@cukz.umcn.nl
Valsecchi
Federica
F
van der Velden
Thea
T
van den Heuvel
Lambertus
L
Monnens
Leo
L
Morigi
Marina
M
D002448:Cell Adhesion / Q000187:drug effects* / Q000502:physiology*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000502:physiology*; D006463:Hemolytic-Uremic Syndrome / Q000209:etiology; D019812:Heparan Sulfate Proteoglycans / Q000502:physiology; D006497:Heparan Sulfate / Q000502:physiology*; D006801:Humans; D007962:Leukocytes / Q000187:drug effects* / Q000502:physiology*; D011133:Polysaccharide-Lyases / Q000494:pharmacology; D022621:Shiga Toxin / Q000008:administration & dosage / Q000633:toxicity*; D022622:Shiga Toxin 1 / Q000008:administration & dosage / Q000633:toxicity; D022641:Shiga Toxin 2 / Q000008:administration & dosage / Q000633:toxicity
D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate; D011133:Polysaccharide-Lyases; D022621:Shiga Toxin; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; C021349:heparitinsulfate lyase