Roles of lysosomal proteinases in the patho-physiological changes of hard tissues.

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Recent studies have suggested that a variety of lysosmal proteinases play an importantrrole in destructive lesion of hard tissues. However, a fundamental question regarding the mechanism of destructive process of hard tissue proteins still remains to be answered. The present studies was undertaken to prepare various lysosomal proteinases and antibodies specific for these enzymes for defining the properties of degradative system responsible for the breakdown of the tissue proteins. In the fiscal year of 1987, the work was concerned chiefly with lysosomal cysteine proteinases cathepsin B and cathepsin H. Preparation of the pure enzymes and their antibodies was accomplished in this year. Comparative analyses with various protease inhibitors and anti-inflammatory agents indicated the difference in catalytic site properties between cathepsins B and H. In the fiscal year of 1988, attention was focused on intracellular aspartic proteinases cathepsin D and cathepsin E. Immunochemical and immunohistochemical studies revealed that these two enzymes had the different distribution and subcellular localization in various tissues and blood cells. cathepsin d was detected in all of the tissues and cells tested, whereas cathepsin E had a relatively limited distribution. In addition, cathepsin D was associated with the lysosome-rich fraction, whereas cathepsin E behaved as a soluble cytosolic enzyme.All through the two years, possible roles of lysosomal proteinases in pathological destructive process of periodontal tissues were investigated. The results obtained from analyses of the gingival crevicular fluid from chronic adult periodontitis patients who had rediographic evidence of alveolar bone loss indicated that the levels of cathepsins B, H, L and medullasin was correlated