HUMAN NEUTROPHIL GELATINASE AND ASSOCIATED LIPOCALIN IN ADULT AND LOCALIZED JUVENILE PERIODONTITIS

In search of direct in vivo evidence of matrix metalloproteinases (MMP s) in periodontal tissue destruction, we studied the presence and loca lization of MMP-9 and neutrophil gelatinase-associated lipocalin (NGAL ) in adult periodontitis (AP) and localized juvenile periodontitis (LJ P) gingival tissue specimens by immunohistochemistry, and the activiti es of gelatinases by Western blot, enzymography, and activity measurem ents, using radioactive gelatin as substrate in gingival crevicular fl uid (GCF) and saliva. In gingival tissue obtained from AP and LJP pati ents, polymorphonuclear leukocyte (PMN) 92-kDa MMP-9 and NGAL were see n in the connective tissue, but both the sulcular and the oral epithel ia were consistently negative. Whereas PMNs located in the gingival bl ood vessels showed strictly cytoplasmic MMP-9 and NGAL immunoreactivit ies, in the case of PMN extravasation the staining reactions extended extracellularly. Gelatinase activities consisting mainly of 92-kDa gel atinase were increased in AP GCF relative to LJP GCF and periodontally healthy control GCF. Western blot with specific anti-NGAL antibodies revealed the presence of 25-kDa NGAL and its high-molecular-weight for ms in AP and LJP GCF and saliva and in culture medium of oral keratino cytes, but not in gingival fibroblast culture medium. We conclude that extravasated degranulating PMNs are the major source of MMP-9 and NGA L in periodontitis gingiva, GCF, and saliva.