Helicobacter pylori interactions with plasminogen

Hellcobacter pylori is the causative agent of chronic gastritis, peptic ulc er, and gastric malignancies. A number of virulence factors have been descr ibed including several adhesins, a cytotoxin, neutrophil-activating protein , and expression of binding of extracellular matrix proteins, like collagen type IV, laminin, and vitronectin, H. pylori strains commonly express bind ing of soluble plasminogen. Coccoid forms also express binding, Plasminogen binding was optimal at pH 7.0. The binding is mediated by two cell surface proteins of 42 and 57 hDa. Scatchard plot analysis showed a straight line with a K-d of 7 x 10(-7) M. Lysine and E-aminocaproic acid inhibited bindin g. The binding domain on the plasminogen molecule is the fifth kringle, min iplasminogen. Plasminogen is converted to plasmin by tissue plasminogen act ivator. During H. pylori infection the activity of tissue plasminogen activ ator is decreased and that of urokinase increased. This is reversed after e radication therapy. The plasminogen binding and conversion to plasmin is th e only proteolytic activity of H. pylori, and may enhance tissue penetratio n and be involved in carcinogenesis. (C) 2000 Academic Press.