Immunocytochemical Localization of Cathepsin D in Rat Junctional Epithelium

Abstract

Localization of cathepsin D was studied in the junctional epithelium (JE) of healthy rat gingivae by immuno-light and -electron microscopy, by means of both the avidin-biotin-peroxidase complex method and a colloidal gold IgG method. At the light-microscopic level, cathepsin D was demonstrated in the JE and oral sulcular epithelium (OSE). Cathepsin D immunoreactivity was remarkable in the coronal portion of the JE and decreased toward its apical portion. However, cathepsin D immunoreactivity in the basal cell layer of the JE was negligible or negative. In the OSE, the granular layer was positive for cathepsin D. In the adjacent connective tissue, many macrophage-like cells (not clear at this level) close to the basal cell layer showed strong immunoreactivity. At the electron microscopic level, cathepsin D was found in the primary lysosomes and trans-cisternae of Golgi apparatus in the JE cells. These lysosomes were often fused together or were fused with cathepsin D-negative intracytoplasmic vacuoles to form secondary lysosomes, which indicated that intracellular digestion may have been in progress. However, neutrophils contained few gold particles based on cathepsin D. It is likely that the amounts of cathepsin D contained in the JE cells and macrophages are larger than those of cathepsin D contained in the neutrophils. These findings provided morphological evidence that JE cells have the same endocytotic capacity as macrophages and neutrophils, and that JE cells participate in the intracellular digestion that is carried out by lysosomal enzymes such as cathepsin D. It is suggested, in addition, that maximum intracellular digestion occurs in the coronal portion of the JE.

Immunocytochemical localization of substance P neurokinin-1 receptors in rat gingival tissue

“…Furthermore, the formation of this superoxide anion (Tanabe et al 1996) and endocytosis of IgG-opsonized materials by neutrophils (Fallman et al 1989;Lew et al 1985) have been reported to depend on the activation of NK 1 -R/G-protein-linked phosphoinositide turnover and the resulting increase in intracellular Ca 2+ concentrations. Judging from the findings that the JE is densely innervated by SP-immunoreactive nerves and that NK 1 -R was found in the JE cells, the proliferation (Schroeder 1986) and endocytotic ability (Ayasaka et al 1993;Yamaza et al 1997) of JE cells and the migration and endocytotic ability of neutrophils may be modulated by the binding of NK 1 -R with SP.…”

PMN responses in chronic periodontal disease: evaluation by gingival crevicular fluid enzymes and elastase‐alpha‐1‐proteinase inhibitor complex

“…the primary azurophilic granules of neutrophils, into the extracellular compartment. CD is located in fibroblasts and macrophages of the subepithelial connective tissue and in desquamating junctional epithelial cells of the gingival crevice (Ayasaka et al 1993). Under lower acidic conditions (pH 3–7), the release of CD, which is inhibited by pepstatin, induces the activation of a variety of enzymes that contribute to the tissue degradation process (Buchmann et al 1994).…”

Proteolytic host cell enzymes in gingival crevice fluid

“…Lysosomal cysteine and aspartic acid proteinases have been detected in several epithelial tissues. Cathepsin D has been detected in the coronal portion of rat junctional epithelium (9). By immunohistological methods cathepsins B, C, D, H, and L have been detected in urinary bladder epithelium (182).…”