Potency of an oxidation-resistant mutant of secretory leukocyte proteinase inhibitor in lipopolysaccharide-induced emphysema in hamsters.
Secretory leukocyte inhibitor (SLPI) is a potent inhibitor of serine proteinases, but sensitive to oxidative inactivation due to a methionine residue in the active centre of the inhibitor. We compared the potency of an oxidation-resistant mutant of recombinant SLPI with native recombinant SLPI in lipopolysaccharide (LPS)-induced emphysema in the hamster. Application of this oxidation-resistant mutant reduced the induced emphysema by 70 and 85% in two separate series of experiments. In contrast, an equal amount of native rSLPI resulted in significantly lower inhibition, 30 and 23%, respectively (P = 0.002). To demonstrate the effect of oxygen radicals upon a single LPS instillation in the lungs, we measured anti-neutrophil elastase activity in lung lavage fluid at 10 and 24 h after the instillation of a mixture of LPS and native rSLPI. We found that residual native rSLPI was only 70 and 55% active, respectively. The rSLPI-mutant remained 93% active in a similar experiment. The native and mutant inhibitor showed equal potency against proteinases in a granule extract of hamster neutrophils. We conclude that the replacement of methionine by leucine in the inhibitory centre of rSLPI results in a decreased sensitivity to oxidative inactivation and that this alone is sufficient to explain the greater efficiency of the rSLPI-mutant in reducing the extent of LPS-induced emphysema.
Stolk
J
J
Department of Pulmonology, University Hospital Leiden, The Netherlands.
Heinzel-Wieland
R
R
Saunders
D
D
Dijkman
J H
JH
Steffens
G
G
D000818:Animals; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D006224:Cricetinae; D004646:Emphysema / Q000139:chemically induced / Q000188:drug therapy*; D066298:In Vitro Techniques; D008070:Lipopolysaccharides; D008647:Mesocricetus; D009154:Mutation; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015842:Serine Proteinase Inhibitors / Q000235:genetics / Q000493:pharmacokinetics / Q000494:pharmacology*
D008070:Lipopolysaccharides; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors