Pneumolysin potentiates oxidative inactivation of alpha-1-proteinase inhibitor by activated human neutrophils.
This study was designed to investigate the effects of the Streptococcus pneumoniae-derived, pro-inflammatory toxin, pneumolysin (8.37 and 41.75 ng/ml), on the oxidative inactivation of alpha-1-protease inhibitor (API) by chemoattractant-activated human neutrophils in vitro. The elastase inhibitory capacity (EIC) of API in supernatants from unstimulated neutrophils, neutrophils treated with pneumolysin only, or with the chemoattractant FMLP (1 microM) only, or the combination of the toxin with FMLP was measured by a colorimetric procedure based on the activity of added porcine elastase. The EIC of API was unaffected by exposure to pneumolysin only, unstimulated neutrophils, or neutrophils treated with pneumolysin only. However, exposure to FMLP-activated neutrophils resulted in a reduction of the EIC of API, which was significantly (P<0.05) augmented by pneumolysin (mean reductions of 16%, 43% and 83% for FMLP only and in combination with 8.37 and 41.75 ng/ml pneumolysin, respectively), and was attenuated by wortmannin (1 microM), an inhibitor of NADPH oxidase, the oxidant-scavenger methionine (100 microM), and depletion of Ca2+ from the cell-suspending medium. These pro-proteolytic interactions of pneumolysin with chemoattractant-activated neutrophils may contribute to the invasiveness of the pneumococcus.
Cockeran
Riana
R
MRC Unit for Inflammation and Immunity, Department of Immunology, Faculty of Health Sciences, University of Pretoria and Tshwane Academic Division of the National Health Laboratory Services, PO Box 2034, Pretoria 0001, South Africa.
Theron
Annette J
AJ
Feldman
Charles
C
Mitchel
Timothy J
TJ
Anderson
Ronald
R
D000328:Adult; D000730:Androstadienes / Q000276:immunology / Q000494:pharmacology; D001426:Bacterial Proteins; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D006801:Humans; D019272:Leukocyte Elastase / Q000276:immunology; D008715:Methionine / Q000276:immunology; D009240:N-Formylmethionine Leucyl-Phenylalanine; D018375:Neutrophil Activation / Q000276:immunology; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology; D010084:Oxidation-Reduction; D019869:Phosphatidylinositol 3-Kinases / Q000276:immunology; D013301:Streptolysins / Q000276:immunology / Q000494:pharmacology*; D013481:Superoxides / Q000276:immunology; D014361:Trypsin Inhibitors / Q000276:immunology / Q000494:pharmacology*; D000077191:Wortmannin; D000515:alpha 1-Antitrypsin / Q000276:immunology*
D000730:Androstadienes; D001426:Bacterial Proteins; D013301:Streptolysins; D014361:Trypsin Inhibitors; D000515:alpha 1-Antitrypsin; C032290:plY protein, Streptococcus pneumoniae; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D008715:Methionine; D019869:Phosphatidylinositol 3-Kinases; D019272:Leukocyte Elastase; D000077191:Wortmannin