leupeptins and Thrombosis

Chives have been used both as food and as medicine. Previously, two fibrinolytic enzymes, ATFE-I (90 kDa) and ATFE-II (55 kDa), were identified in chives (Allium tuberosum), a perennial herb. In the present work, ATFE-II was purified by ion-exchange chromatography followed by gel filtration. In addition, the enzyme properties of ATFE-I and ATFE-II were compared. The molecular mass and isoelectric point (pI value) of ATFE-II were 55 kDa and pI 4.0, respectively, as revealed using one- or two-dimensional fibrin zymography. ATFE-II was optimally active at pH 7.0 and 45°C. ATFE-II degraded the Aα-chain of human fibrinogen but did not hydrolyze the Bβ-chain or the γ-chain, indicating that the enzyme is an α-fibrinogenase. The proteolytic activity of ATFE-II was completely inhibited by 1 mM leupeptin, indicating that the enzyme belongs to the cysteine protease class. ATFE-II was also inhibited by 1 mM Fe²(+). ATFE-II exhibited high specificity for MeO-Suc-Arg-Pro-Tyr-p-nitroaniline (S-2586), a synthetic chromogenic substrate of chymotrypsin. Thus proteolytic enzymes from A. tuberosum may be useful as thrombolytic agents.

Topics: Chive; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Drug Discovery; Ferrous Compounds; Fibrinogen; Fibrinolysis; Fibrinolytic Agents; Hydrogen-Ion Concentration; Hydrolysis; Isoelectric Point; Isoenzymes; Leupeptins; Molecular Weight; Oligopeptides; Plant Components, Aerial; Plant Proteins; Substrate Specificity; Temperature; Thrombolytic Therapy; Thrombosis

It has been shown that endothelial cell (EC) activation and tissue factor (TF) upregulation in EC and monocytes by antiphospholipid antibodies (aPL Abs) leads to a prothrombotic state and involves translocation of nuclear factor-kappa B (NF-kappaB). Here we examined the effects of an NF-kappaB inhibitor on aPL-induced thrombosis, TF activity, and EC in vivo. We treated CD1 mice with IgG from a patient with antiphospholipid syndrome (IgG-APS) or with control IgG (IgG-NHS). The adhesion of leukocytes (number of white blood cells) to EC in cremaster muscle (as an indication of EC activation) as well as the size of an induced thrombus in the femoral vein of the mice were examined. Some mice in each group were infused with 10 microM MG132 (an inhibitor of NF-kappaB). TF activity was determined using a chromogenic assay in homogenates of carotid arteries and in peritoneal cells of mice. In vivo, IgG-APS increased significantly the number of white blood cells adhering to ECs (4.7 +/- 2.2) when compared to control mice (1.5 +/- 0.8), and these effects were significantly reduced when mice were pretreated with MG132 (0.8 +/- 0.2). IgG-APS increased significantly the thrombus size and MG132 inhibited that effect (93%). Treatment of the mice with IgG-APS also induced significantly increased TF function in peritoneal cells and in homogenates of carotid arteries. Pretreatment of the mice with MG132 abrogated those effects significantly. Mice injected with IgG-APS or with IgM-APS with or without the inhibitor had medium-high titers of anticardiolipin antibodies in serum at the time of the surgical procedures. The data show that prothrombotic and proinflammatory properties of IgG-APS and IgM-APS are downregulated in vivo by an NF-kappaB inhibitor. These findings may be important in designing new modalities of targeted therapies to treat thrombosis in patients with APS.

Topics: Animals; Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Cell Adhesion; Endothelial Cells; Humans; Leupeptins; Male; Mice; Middle Aged; NF-kappa B; Thromboplastin; Thrombosis

Peptide aldehyde transition state analogue inhibitors of serine and cysteine proteases have been used to selectively inhibit proteases for which prior evidence supports a role in tumor cell metastasis. These enzymes include cathepsin B, urokinase plasminogen activator (PA), and thrombin. The inhibition constants of the peptidyl aldehyde inhibitors show that they are highly selective for a particular targeted serine or cysteine protease. The inhibitors are introduced by i.p. injection or by miniosmotic pumps into syngeneic C57BL/6 mice also given injections of B16-F10 melanoma cells, and the number of metastatic foci in the lung was determined. While the injection protocol gave an initially high but changing in vivo concentration of inhibitor over time, the minipump implant gave a constant steady state concentration of inhibitor over 5-7 days. Minipump infusion of leupeptin (acetylleucylleucylargininal), a strong inhibitor of cathepsin B at a steady state plasma concentration 1000-fold greater than its Ki(cathepsin B), gave no significant decrease in lung colonization by the B16 tumor cells. Ep475, a stoichiometric irreversible peptide inhibitor of cathepsin B-like proteases, also did not significantly inhibit metastatic foci formation. Introduction of selective inhibitors of urokinase PA, tert-butyloxycarbonylglutamylglycyl-argininal and H-glutamylglycylargininal at concentrations near its Ki, produced no significant decrease in mouse lung colonization. The selective thrombin inhibitor D-phenylalanylprolylargininal infused to a steady state concentration 100-fold greater than its Ki dramatically increased B16 melanoma colonization of mouse lung. The results indicate that neither secreted cathepsin B-like nor urokinase PA have roles in B16 colonization of mouse lung, while thrombin may have a role in preventing metastasis. These experiments do not eliminate roles for a cathepsin B-like enzyme or urokinase PA in the initial steps of the metastatic process.

Topics: Animals; Cathepsin B; Cathepsins; Cysteine Endopeptidases; Dose-Response Relationship, Drug; Endopeptidases; Female; Fibrinolysis; Leucine; Leupeptins; Lung Neoplasms; Melanoma; Mice; Mice, Inbred C57BL; Neoplasm Metastasis; Peptide Hydrolases; Plasminogen Activators; Plasminogen Inactivators; Protease Inhibitors; Serine Endopeptidases; Thrombin; Thrombosis