NoBlood

Gastroenterology

June 2003 • Volume 124 • Number 7



Basic-alimentary tract
Helicobacter pylori binds von Willebrand factor and interacts with GPIb to induce platelet aggregation



Background & Aims: Clinical studies have suggested an association between cardiovascular disease and infection with Helicobacter pylori. We examined the effect of H. pylori on platelets and the mechanism of the interaction.

Methods: Three of 5 strains of H. pylori induced platelet aggregation with a lag time of 5 ± 2 minutes that was independent of the toxigenic genes cagA and vacA. Aggregation was inhibited completely by aspirin and a glycoprotein (GP) IIb/IIIa antagonist. Aggregation also was inhibited by monoclonal antibodies that prevented the von Willebrand factor (vWF) interaction with GPIb. vWF-coated H. pylori bound to cells transfected with GPIb but not to mock transfected cells and this was inhibited by an antibody to GPIb.

Results: The interaction with platelets appeared to be mediated by vWF because platelet aggregation was blocked by an antibody to vWF. Moreover, a strain of H. pylori that induced platelet aggregation bound vWF to a greater extent than a nonaggregating strain. Aggregation also required IgG and could be inhibited by an antibody to the platelet IgG receptor (FcRIIA).

Conclusions: Some strains of H. pylori induce platelet activation mediated by H. pylori-bound vWF interacting with GPIb, and supported by IgG. These platelet-H. pylori interactions may contribute to the pathogenesis of H. pylori-associated peptic ulcer disease and to the association between H. pylori infection and cardiovascular disease, whereas local platelet effects may contribute to the pathogenesis of H. pylori-associated peptic ulcer disease.

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Mr. Jan B. Wade
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