ELASTIN DERIVED PEPTIDES PROTECT ELASTIC FIBERS DEGRADATION BY HUMAN NEUTROPHIL ELASTASE - IN-VITRO AND IN-VIVO STUDIES USING A MECHANICALLY INDUCED RAT GINGIVAL INFLAMMATORY MODEL

An elastin peptide (kE(57)) Obtained from organoalkaline hydrolysis of calf ligamentum nuchae insoluble elastin, was isolated by gel permeat ion on Sephadex G150 and high performance Liquid chromatography on a T SK G 3000 SW column. It possessed an average Mr=57,000 and similar ami no acids composition as its insoluble counterpart. kE(57) behave as a competitive inhibitor of human neutrophil elastase (HNE) with K-i=1.4 mu M; it also inhibited porcine pancreatic elastase (PPE) but less eff iciently K-i=180 mu M. Identification of elastic fibres in rat gingiva was ascertained by light and electron microscopic studies. Morphometr ic studies indicated that rat gingiva contained similar levels of elas tic fibres (=2%) as human skin; elastic fibres networks from both tiss ues also displayed high structural analogy. Gingival chronic inflammat ion was induced in rats by mechanical impaction associated with an hyp erglucidic diet. After 5 weeks, the levels of rat gingiva elastic fibr es, decreased from Vv=1.94+/-0.1% to Vv= 1.02+/-0.06%. Local injection s of kE(57): 100 mu g per day, 5 days a week for 5 weeks did restore t he integrity of the gingiva elastic fibres network: Vv=1.84+/-0.1. Wit hout influencing leucocyte infiltration, it is proposed that elastin-d erived peptides, acting as potent competitive inhibitor of neutrophil elastase involved in periodontitis, might be of therapeutic value.