cathepsin-g and Emphysema

Flavanol (-)epigallocatechin-3-gallate is shown to be a potent natural inhibitor of leukocyte elastase that may be used to reduce elastase-mediated progression to emphysema and tumor invasion. This phyto-factor, abundant in green tea, exerts a dose-dependent, noncompetitive inhibition of leukocyte elastase at a noncytotoxic concentration and is effective in neutrophil culture. This inhibition shows an IC(50) of 0.4 microM, 30 times higher than the alpha1-protease inhibitor but lower than other known natural and synthetic elastase inhibitors. The flavanol inhibits leukocyte elastase at concentrations of 50, 150, and 2500 times lower than that effective on gelatinases (MMP-2 and MMP-9), thrombin, and cathepsin G, respectively, and also blocks elastase-mediated activation of MMP-9.

Topics: Catechin; Cathepsin G; Cathepsins; Cells, Cultured; Dose-Response Relationship, Drug; Emphysema; Enzyme Activation; Enzyme Inhibitors; Gelatinases; Humans; Inflammation; Leukocyte Elastase; Neutrophils; Phytotherapy; Serine Endopeptidases; Thrombin

To determine whether human neutrophil cathepsin G can act by itself or in concert with human neutrophil elastase to destroy elastic fibers in vivo, we used cryostat sections of human skin as an ex vivo substrate for these leukoproteinases. Specifically stained dermal elastic fibers were quantitated using an accurate and almost entirely automatic morphometric procedure that included computerized threshold selection and elimination of non-elastic dark elements. AA, the area fraction occupied by the dermal elastic fibers, was found to be 0.100 +/- 0.014 (mean +/- SD) for 21 control skin sections originating from a single donor. Measurement of the fiber diameters in these control sections (2.4 +/- 0.8 microns [mean +/- SD]) allowed calculation of the Weibel factor used to convert AA into Vv, the volume fraction occupied by the elastic fibers: Vv was 0.028 +/- 0.004 (mean +/- SD). Incubation of skin sections with elastase, cathepsin G, or mixtures of the two enzymes resulted in an important decrease in AA accompanied by a slight increase in the average fiber diameter. The largest increase (14%) was noticed for cathepsin G and was due to a preferential attack of thin fibers and to fiber fragmentation. The AA of fibers remaining after elastolytic activity of cathepsin G was 20 to 30% that of elastase in this ex vivo assay. On the other hand, cathepsin G stimulated the elastolytic activity of elastase. For instance, the activity of a mixture of 1.1 microM elastase and 1.5 microM cathepsin G was 1.9-fold higher than the sum of the activities of the individual proteinases. The stimulation increased with the cathepsin G concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Cathepsin G; Cathepsins; Elastin; Emphysema; Histocytochemistry; Humans; Image Processing, Computer-Assisted; Neutrophils; Pancreatic Elastase; Serine Endopeptidases; Skin; Solubility; Staining and Labeling

Studies were designed to explore the possibility that human polymorphonuclear leukocyte granule constituents in addition to elastase (HLE) had the potential to cause emphysema. A two-step purification of three serine proteinases was developed. Granule extract proteins were initially separated by dye-ligand affinity chromatography. Fractions eluted were divided into four pools. Hamsters were given a single intratracheal instillation of saline +/- 0.1 mg protein of each pool. While pool 2 contained HLE and cathepsin G, the most dramatic bullous emphysema developed in animals treated with pool 4. The esterase from pool 4, designated proteinase 3 (PR-3) was purified, characterized in vitro, and tested for its ability to cause emphysema. PR-3 is a neutral serine proteinase with isoenzyme forms. Its ability to degrade elastin at pH 6.5 is slightly greater than that of HLE, but it is less active than HLE at pH 7.4 or 8.9. PR-3 has weak activity against azocasein. Its ability to degrade hemoglobin is intermediate to that of HLE and cathepsin G at pH 7.4. PR-3 has no activity against chromogenic substrates specific for HLE or cathepsin G. Its pI is substantially less than HLE or cathepsin G. It is also immunologically distinct from HLE. It induces emphysema in hamsters commensurate with that of HLE. We conclude that PR-3 may be important in the pathogenesis of human emphysema.

Topics: Animals; Cathepsin G; Cathepsins; Cricetinae; Elastin; Emphysema; Humans; Leukocyte Elastase; Myeloblastin; Naphthols; Neutrophils; Pancreatic Elastase; Serine Endopeptidases

Topics: Animals; Cathepsin G; Cathepsins; Cattle; Chymotrypsin; Elastin; Emphysema; Endopeptidases; Humans; Kinetics; Leukocytes; Lung; Pancreatic Elastase; Serine Endopeptidases; Substrate Specificity