Vitronectin binding by Helicobacter pylori

Abstract

Vitronectin, a serum and extracellular matrix protein involved in immunological reactions, interacts with Helicobacter pylori strains. Of the 20 H. pylori strains tested three strains bound more than 50% of the vitronectin added, five strains bound 25–40%, nine strains bound 10–20% and three strains bound 5–8% vitronectin. Two strains, one with high‐ and one with low‐binding properties, were selected for further characterization of 125I‐vitronectin binding. Binding to the urea‐activated 125I‐labelled vitronectin was fast, saturable and reversible when an excess of unlabelled vitronectin was added to the bacteria with bound 125I‐vitronectin. The binding was heat‐ and protease‐sensitive, suggesting that the binding was mediated by bacterial cell‐surface proteins. Since components such as fetuin and orosomucoid but not asialofetuin inhibited the binding, sialic‐acid specific proteins, related to H. pylori sialic‐acid specific haemagglutinins, were probably involved.

Role of Helicobacter pylori surface structures in bacterial interaction with macrophages.

“…aophago-Vitronectin (or S-protein) is a highly glycosyn surface lated protein of serum, tissues and extracellular agocytic) matrices, characterised as a cell attachment factor.21 This glycoprotein binds to many bacteria among them to H pylori microorganisms. 22 During complement activation, vitronectin is incorporated into C5b-C7 complex preventing formation of the membrane attack complex of complement on a macrophage surface.21 23 Therefore, vitronectin binding bacteria can avoid bacteriolysis. On the other hand, soluble S-C5b-C7 complexes as well as S-C5b-C9 complexes can bind to macrophage vitronectin receptors24 and heparin or heparan sulphate structures on macrophages.…”

“…Conclusions-The results suggest that H pylori surface compounds binding host proteins such as fetuin, heparin/haparan sulphate, hyaluronic acid, and vitronectin in the presence of complement, could allow the bacteria to avoid phagocytosis. (Gut 1997;40: [20][21][22][23][24] Keywords: Helicobacterpylori, macrophages, fetuin, heparin, vitronectin.…”

Helicobacter pylori Interactions with Host Serum and Extracellular Matrix Proteins: Potential Role in the Infectious Process

“…It also interacts with the C5b-9 complex inhibiting cell lysis by the complement system and protects thrombin from inactivation by antithrombin III. Vitronectin binds to H. pylori (53%) (82,83), and this reaction is fast, saturable, and reversible. Binding is heat and protease sensitive, suggesting that it is mediated by bacterial cell surface proteins.…”

“…Low (5 to 8%) and high (Ͼ50%) vitronectin binders were observed among hemagglutinating strains. Purified vitronectin, which includes an urea-activation step of vitronectin, binds to H. pylori in a fast and saturable way (82). On the other hand, Trust et al (101) reported that only small amounts of vitronectin, purified by another method, bound to H. pylori.…”

A study of the interaction between Helicobacter pylori and components of the human fibrinolytic system

“…Like other bacterial pathogens, H. pylori expresses surface proteins with affinity for several human proteins, components of the mammalian extracellular matrix such as laminin, vitronectin, collagen types I and IV and plasminogen (14)(15)(16)(17)(18). Plasminogen binding to the surface of H. pylori has been shown to be inhibited by lysine, lysine analogues and miniplasminogen (fifth kringle and catalytic domain (1)), suggesting an important role of the fifth kringle structure of the zymogen which possibly interacts with two surface proteins of 42 and 57 kDa (19).…”