PROTECTIVE EFFECT OF OLEOYL PEPTIDE CONJUGATES AGAINST ELASTOLYSIS BYNEUTROPHIL ELASTASE AND KAPPA-ELASTIN-INDUCED MONOCYTE CHEMOTAXIS

Elastin can impair the human neutrophil elastase (HNE) inhibitory capa city of elastase inhibitors. We synthesized oleoyl-alanyl-alanyl-proly l-valine (Ol-Ala-Ala-Pro-Val-OH) (oleoyl peptide) and the amides (NH2 and NH-C3H7) of this peptide and studied their HNE-inhibitory potencie s using succinyl-alanyl-alanyl-alanine-p-nitroanilide (Suc-Ala-Ala-Ala -pNA) or H-3-labeled elastin as substrates, as well as cryostat sectio ns of rabbit skin as an ex vivo substrate. Using Suc-Ala-Ala-Ala-pNA, Ol-Ala-Ala-Pro-Val-OH had an IC50 of 3 muM. When the COOH terminal of the oleoyl peptide was derivatized to amide forms, the compound lost i ts ability to interact with HNE while keeping its elastin-protecting f unction: IC50 values for NH2 and NH-C3H7 derivatives were 22 and 17 mu M, respectively. Also, the HNE-inhibitory capacity of 01-Ala-Ala-Pro-V al-OH was only reduced 2-fold by using elastin as a substrate. This de crease was much lower than those determined with other HNE inhibitors of similar potency and could be accounted for by the ability of oleoyl peptide to bind to elastin. Cryostat sections of rabbit skin were als o used as an ex vivo substrate for assessing the elastin-protecting pr operty of 01-Ala-Ala-Pro-Val-OH. Preincubating HNE and oleoyl peptide before application to tissue sections led to an IC50 of 8 muM, close t o the value determined with elastin as a substrate. Treatment of secti ons with oleoyl peptide before adding HNE gave a lower IC50 (4 muM). O l-Ala-Ala-Pro-Val-OH could suppress kappa elastin (kE)-induced chemota xis of human monocytes. Optimal kE chemotactic effect occurred at 13 n M, and 50% inhibition of chemotaxis was observed in presence of 75 muM of this oleoyl peptide. In contrast, oleoyl peptide had no influence on formylmethionylleucylphenylalanine-induced chemotaxis of either hum an monocytes or rat polymorphonuclear neutrophils. Lipophilic substanc es such as oleoyl peptide, which simultaneously behave as HNE inhibito rs, elastin-protecting agents, and modulators of monocytes chemotaxis induced by elastin fragments, may thus present several advantages in t he treatment of human lung diseases.