cathepsin-g and Shock--Septic

Plasma levels of antithrombin III, alpha 2-macroglobulin and inter-alpha-trypsin inhibitor, as well as those of various clotting, complement and other plasma factors, were significantly decreased in 18 patients suffering from hyperdynamic septic shock. A similar statistically significant reduction of the concentrations of several plasma factors (prothrombin and antithrombin III, plasminogen and alpha 2-plasmin inhibitor, complement factor C3 and clotting factor XIII) was observed in experimental endotoxaemia. In this model the reduction in the plasma levels of these factors was considerably diminished by the intravenous injection of a granulocytic elastase--cathepsin G inhibitor of lower molecular weight from soybeans. The results of both studies indicate that consumption of plasma factors in the course of Gram-negative sepsis proceeds not only via the classical routes (by activation of the clotting, fibrinolytic and complement cascades by system-specific proteinases such as thrombokinase or the plasminogen activator) but also to an appreciable degree of unspecific degradation of plasma factors by neutral proteinases such as elastase and cathepsin G. The endotoxin-induced release of both sorts of proteinases, the system-specific ones and the unspecific lysosomal proteinases from leucocytes and other cells, is likely to be mainly responsible for the consumption of antithrombin III and alpha-2-macroglobulin via complex formation (followed by elimination of the complexes) and the increased turnover of the inter-alpha-trypsin inhibitor as observed in the clinical study. The therapeutic use of an exogenous elastase--cathepsin G inhibitor in the experimental model was stimulated by the observation that human mucous secretions contain and acid-stable inhibitor of the neutral granulocytic proteinases, called HUSI-I or antileucoproteinase. This inhibitor protects mucous membranes and soluble proteins against proteolytic attack by leucocytic proteinases released in the course of a local inflammatory response. Preliminary results indicate that HUSI-I, which is produced by the epithelial cells of mucous membranes, does not belong to any known structural type of acid-stable proteinase inhibitor. The search for other candidates suitable for medication in humans led to the discovery of a potent elastase--cathepsin G inhibitor, called eglin, in the leech Hirudo medicinalis. This acid-stable inhibitor with a molecular weight close to 8100 has an unusual structural propert

Topics: Adolescent; Adult; Aged; Animals; Cathepsin G; Cathepsins; Cattle; Disease Models, Animal; Dogs; Endotoxins; Escherichia coli; Humans; Middle Aged; Pancreatic Elastase; Protease Inhibitors; Sepsis; Serine Endopeptidases; Shock, Septic

Dog polymorphonuclear leukocyte cathepsin G was isolated from a granule extract using a two-step procedure including affinity chromatography on a Trasylol-Sepharose gel and ion-exchange chromatography on a CM 52 column. 22 of the first 24 N-terminal amino acids were determined and showed 83% and 71% identity to those of human and rat cathepsin G, respectively. Total amino-acid composition demonstrated the basic nature of the protein. In an SDS/polyacrylamide-gel electrophoresis the protein showed an Mr of 29,400 compared to the Mr of 26,800 calculated from the total amino-acid composition. The enzyme was shown to form complexes with alpha 1 alpha 2-macroglobulin and alpha 1-proteinase inhibitor. A specific enzyme-linked immunosorbent assay was developed for the determination of cathepsin G/alpha 1-proteinase inhibitor complex in dog plasma and tissue fluids. The mean concentration of cathepsin G in normal dog plasma was determined to be 38 micrograms/l, measured as cathepsin G/alpha 1-proteinase inhibitor complex. When active dog cathepsin G was added to normal dog plasma in vitro, approximately 56% could be measured by the assay. Slow intravenous infusion of a lethal dose of endotoxin in dogs was followed by a marked drop in white blood cell count and thrombocytes and a simultaneous rapid increase in plasma cathepsin G concentration, reaching a maximum level of 150 micrograms/l. Bile-induced experimental pancreatitis in dogs was accompanied by successive increase in cathepsin G levels in plasma as well as in peritoneal exudates, reaching a maximum level of about 300 micrograms/l in plasma and 18 mg/l in the exudates during the late stages of disease.

Topics: Acute Disease; Amino Acid Sequence; Animals; Cathepsin G; Cathepsins; Chromatography, Gel; Chromatography, Ion Exchange; Dogs; Enzyme-Linked Immunosorbent Assay; Humans; Lipopolysaccharides; Molecular Sequence Data; Molecular Weight; Neutrophils; Pancreatitis; Reference Values; Sequence Homology, Nucleic Acid; Serine Endopeptidases; Shock, Septic; Substrate Specificity