Receptor-mediated binding and internalization of leukocyte elastase by alveolar macrophages in vitro.

Campbell, Edward J.; White, R; Senior, Robert M.; Rodríguez, Rafael; Kuhn, Charles

doi:10.1172/jci109530

Cited by 110 publications

(47 citation statements)

References 44 publications

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“…Accordingly, it is not possible to attribute in vivo nonimmune cleavage of C5 substrates to pulmonary macrophage-derived proteases. It is known that stimulated PM secrete a protease (41) capable of cleaving C5, but whether this is a unique protease synthesized by PM or an enzyme released by PMN leukocytes and then pinocytozed by PM as suggested by Campbell et al (42) remains to be determined. However, the role of macrophage-derived proteins in the generation of C5a leukoattractant activity was examined (Fig.…”

Section: Discussionmentioning

confidence: 99%

Complement Activation in Cystic Fibrosis Respiratory Fluids: in Vivo and in Vitro Generation of C5a and Chemotactic Activity

et al. 1986

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ABSTRACT. Experiments performed in vitro have demonstrated that leukocyte neutral proteases produce an important mediator of inflammation, C5a, by proteolysis of the C5 component of the complement system. Cystic fibrosis (CF) lung fluids were characterized by high levels of neutrophils (39% of total cells versus 2% in normals) and contained significantly elevated amounts of elastolytic activity (mean 17.7 ng/pg total protein) compared to the lung fluids obtained from normal volunteers (0.2 ng elastolytic activitylpg protein, p = 0.001). The objective of these studies was to determine if complement activation and complement-derived chemotactic activity are present in CF lung fluids. C3c peptide representing activation of C3 could not be identified in the bronchial-alveolar lung lavage fluids of normal subjects but was readily identified by means of crossed immunoelectrophoresis "in CF lung fluids (n = 9, mean 49% of C3); the mean level of C3 was decreased in CF lung specimens. Chemotactic activity was significantly elevated in lung fluids of the CF patients when compared to normal lung fluids. Using gel-filtration chromatography and a sensitive radioimmunoassay the chemotaxin present in CF specimens was identified as the anaphylatoxin C5a. C5a levels in the bronchial-alveolar lavage fluids of CF patients was inversely related to volume in liters expired in 1 s of a forced expiratory maneuver expressed as a percent of vital capacity determined from a forced expiratory maneuver ( r = -0.72). Because there was a direct relationship between the total elastolytic activity present in CF airways and the concentration of C5a ( r = 0.97, p = 0.03), it was postulated that airway proteases with elastolytic activity also cleave C5, nonimmunologically producing C5a. Detailed inhibition assays revealed that much of the total elastolytic activity had the inhibition profile of a serine proteinase. The levels of the serine proteinases were closely correlated with the numbers of neutrophilic leukocytes present per ml of lavage fluid ( r = 0.7, p = 0.05).However, inhibitors of leukocyte serine proteases did not prevent the generation of additional chemotactic activity

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Section: Discussionmentioning

confidence: 99%

Complement Activation in Cystic Fibrosis Respiratory Fluids: in Vivo and in Vitro Generation of C5a and Chemotactic Activity

et al. 1986

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“…Thus, human neutrophil leukocyte elastase äs well äs a 2 -macroglobul· in-elastase complexes are pinocytosed and phagocytosed, respectively, by alveolar macrophages, suggesting that at least some of the elastase activity found in macrophages may be ingested rather than formed de novo (1)(2)(3)(4). A previous report from this laboratory presented evidence that bronchoalveolar lavage-derived human granulocytes accumulate appreciable amounts of a r proteinase inhibitor-elastase complexes during passage across the blood-air barrier (5).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Elastase and α1-Proteinase Inhibitor-Elastase Uptake by Polymorphonuclear Leukocytes and Evidence of an Elastase-Specific Receptor

Dwenger¹,

Tost²,

Holle³

1986

Clinical Chemistry and Laboratory Medicine

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Summary:Neither resting nor stimulated isolated human polymorphonuclear leukocytes did bind or ingest preformed complexes of a r prpteinase Inhibitor and unlabeled/ 125 I-labeled human leukocyte elastase. In contrast, granulocytes bound unlabeled/ 125 I-labeled elastase and the extent of binding was reduced in the presence of respirätory burst stimulators, such äs 4ß-phorbol 12ß-myristate 13a-acetate, E. coli endotoxin, and N^formyl-jL-methionyl-L-leucyl-L-phenylalanine. In association/dissociation and competition Inhibition experiments it was demonstrated that granulöcyte^-elastase binding was specific and saturable. From Scatchard and non-linear regression analysis there was evidence of a two-class receptor model with independent binding sites. Calculated by the non-linear regression method assuming a two-class receptor model the characteristics of the high affinity/low capacity binding site were K! = 216 ± 129 · l O 6 l · mol" 1 (x ± s; n = 3) and Rj = 1.38 ± 0.95 nmol · 1~* corresponding to 0.083 · 10 6 receptors per cell, whereäs the low affinity/ high capacity binding site had the characteristics K 2 = 0.50 ± 0.09 -10 6 l-mol^1 and R 2 = 237 ± 103 nmol · l" 1 corresponding to 14.3 + 6.2 -10 6 receptors per cell. ]Elastase-Bindung in Gegenwart der respiratory burst-Stimulantien 4ß-Phorbol-12ß-myristat-13a-acetat, E. co/rVEndotoxin und Formyl-methionyl-leucyl-phenylalanin erniedrigt ist. Aus Assoziations-/Dissoziationsund Kompetitions-Inhibitions-Experimenten geht hervor, daß die Granulocyten-Elastase-Bindung spezifisch und sättigbar ist. Scatchard-und nichtlineare Regressions-Analyse deuten auf ein zweiklassiges Modell unabhängiger Rezeptoren hin. Aus der nichtlinearen Regressionsanalyse ergeben sich unter Annahme eines zweiklassigen Rezeptormodelis die Bindungskonstanten Kj = 216 ± 129 · l O 6 1 · mol' 1 (x ± s; n = 3) und Rj = 1,38 ± 0,95 nmol · l" 1 entsprechend 0,083 · l O 6 Rezeptoren pro Zelle für die hochaffine/niedrigkapazitive Bindungsstelle, während die niedrigaffine/hochkapazitive Bindungsstelle die Konstanten K 2 = 0,50 ± 0,09 • 10 6 l -mol-1 Und R 2 « 237 ± 103 nmol · l^1 entsprechend 14,3 ± 6,2 · 10 6 Rezeptoren pro Granulocyt besitzt. Untersuchungen zur Elastase* und a,i~Proteinaseinhibitor-Elastase-Aufnahme polymorphkerniger Leukocyten und Nachweis eines Elastaserezeptor^Systems

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“…As the name implies, this system recognizes mannose and fucose residues on glycoproteins and is capable of binding extracellular protein at the cell surface. Campbell demonstrated that alveolar macrophages were capable of ingesting a neutral serine proteinase, human neutrophil elastase, by a receptor-mediated process that also bound lactoferrin and cathepsin G and later releasing quantities of active enzyme in response to hypoxic stress (29,34,35). This binding and uptake was blocked by fucoidan.…”

Section: Resultsmentioning

confidence: 99%

Uptake of extracellular enzyme by a novel pathway is a major determinant of cathepsin L levels in human macrophages.

Reilly

Chen²,

Sailor³

et al. 1990

J. Clin. Invest.

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The phorbol myristate acetate (PMA)-differentiated myelomonocytic cell line, THP-1, and human alveolar macrophages contain the cysteine proteinase cathepsin L. This enzyme is synthesized as a 43-kD proenzyme and processed to the active 25-kD form. Differentiation of THP-1 cells in the presence of human serum resulted in a increase in the size of the vacuolar compartment and the accumulation of more 25-kD cathepsin L antigen, as compared with THP-1 cells differentiated in the presence of fetal calf serum. Cells cultured in both types of sera have equivalent levels of cathepsin L mRNA. Metabolic labeling experiments demonstrated equivalent rates of synthesis, processing to the active form, and persistence in both culture conditions. An extracellular source of enzyme was documented by immunoblotting human serum which demonstrated 25-kD cathepsin L antigen; furthermore, we demonstrated that both THP-1 cells, differentiated in human serum, and human alveolar macrophages take up the 43-kD proenzyme and process it to the 25-kD form. Thus, human serum contains a factor(s) that induces both a marked increase in the size of the vacuolar compartment in differentiated THP-1 cells and a novel pathway that is responsible for the uptake and processing of extracellular cathepsin L. The activity of this inducible pathway is a major determinant of levels of intracellular cathepsin L. Cathepsin L is a potent elastase and the regulation of its uptake and processing may play a role in the pathogenesis of disease processes characterized by the destruction of elastin, such as pulmonary emphysema. (J. Clin. Invest. 1990. 86:176-183.)

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Receptor-mediated binding and internalization of leukocyte elastase by alveolar macrophages in vitro.

Cited by 110 publications

References 44 publications

Complement Activation in Cystic Fibrosis Respiratory Fluids: in Vivo and in Vitro Generation of C5a and Chemotactic Activity

Complement Activation in Cystic Fibrosis Respiratory Fluids: in Vivo and in Vitro Generation of C5a and Chemotactic Activity

Evaluation of Elastase and α1-Proteinase Inhibitor-Elastase Uptake by Polymorphonuclear Leukocytes and Evidence of an Elastase-Specific Receptor

Uptake of extracellular enzyme by a novel pathway is a major determinant of cathepsin L levels in human macrophages.

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